REPORT FINAL

R.V. COLLEGE OF ENGINEERING
DEPARTMENT OF MECHANICAL ENGINEERING Page 1
CHAPTER-1
1.0 INTRODUCTION TO MODULAR FIXING FRAMES
The primary focus of this project work is on product development activities that
benefit from the participation of all the core functions defined as marketing, design,
and manufacturing. The integrative methods in this project are structured by a step-
by-step approach for completing the developmental activities.
The project was assigned by Schneider Electric under the Wiring Devices (WDs)
department. The Enclosures Competency was the team in which the project was
completed under the wiring devices department. Study and Analysis of Enclosures for
the Wiring devices was the project assigned. Under which the ‘Modular market’ was
the major focus and concentration of study and analysis.
After an initial study and analysis of modular market for different enclosures
products, various limitations and problem statements under the modular market were
identified and discussed. One such dynamic problem statement involving the Fixing
Frames (FFs) was taken the project definition as “Design and Development of Fixing
Frames for Wiring Devices”. The limitation in the fixing frames was the inability of
simultaneous and flexible installation for both horizontal and vertical mounting
practices. In present system, the fixing frame can be mounted on to the wall for
horizontal installation practice, but the same fixing frame cannot be used for vertical
mounting to the wall. So this current project focuses on the design and developmental
processes in coming up with a solution which offers better flexibility in terms of
functionality and usability for both types of installation practice.
Therefore, this introductory chapter deals with the requirements in terms of
costumer voice for developing the product. It provides a comprehensive background
to the market segments and range, study and analysis of modular market,
classification of fixing frames and competitor product technical analysis as a part of
market survey and acquisition of market specifications. The research and prior arts
work are discussed through literature survey, the motivation to the project work
followed by the project objectives and methodology to carry out the project activities
are discussed.

1.1 CUSTOMER NEEDS ASSESSMENT
Indentifying customer needs is an integral part of the concept development phase of
the product development. The resulting customer needs are used to guide the team in
establishing product specifications, generating product concepts, and selecting a
product concept for further development.
Reconstruction and renovation of industries and buildings are bringing in changes
in the ways of installing the wiring devices to the walls to make the aesthetic
appearance more appealing, trendy and fashionable. It is also a fact that people are
fast becoming aware and making a conscious effort to save space by making working
places more compact promoting conservation of energy. These ideologies have
brought about a change in the installation systems and practices of wiring devices
from a more orthodox way of installing from horizontal to vertical orientation.
Keeping the ergonomics and the suited comfort of operation of the wiring devices in
mind, there is a need to have definite solution which can offer flexibility when it
comes to using the same set enclosures both horizontally and vertically depending
upon the need and requirement of installation.
The fixing frame (FF) of the enclosure assembly is one such variable enclosure
component which holds the wiring devices horizontally or vertically depending on
requirement of use. Therefore, there is an immediate need to come up with a universal
and standard design of fixing frame which can be flexibly used for both horizontal
and vertical systems of installation. All possible combinations and scenarios of
assemblies for both vertical and horizontal installation systems are to be considered
for the newly designed fixing frame to satisfy the standards that are currently in use in
the market. It is important to satisfy the customer needs that meet and also match up
to the upgrading technologies in terms of orientation, style and comfort. Further more
importantly the new product designed should be feasible and economical when it is
put to production in huge numbers keeping the manufacturing parts, costs and time
minimum. And also keeping the installation time of the new product as low as
possible when it comes to installing the wiring devices (WDs) in high raised
buildings.

1.2 ENCLOSURES AND WIRING DEVICES
Every wiring device going into the wall needs to be protected and covered by an
“Enclosure” which fits the entire wiring set into the wall. The case or housing of
apparatus, or the fence or walls surrounding an installation to prevent personnel from
accidentally contacting energized parts to protect the equipment from physical
damage is as shown in the Fig 1.1.
Figure 1.1 Exploded view of enclosures [1]; Courtesy: Schneider Electric
1.2.1 PRODUCT DESCRIPTION
A “fixing frame” for a wiring device includes a metal- made frame body formed into
a frame shape and having a central opening portion. The frame body is configured to
hold the wiring device with a portion of the wiring device inserted into the opening
portion. The fixing frame further includes a resin-made sleeve provided in the frame
body as shown in the Fig 1.2.
The sleeve is configured to engage with an engaging claw of a decoration plate
attached to a front surface side of the frame body. In this manner, a wiring device
such as a switch or a socket is embedded in it, and arranged on, an installation surface
by means of a fixing frame. Electric wires, screws and the like are hidden by a
decoration plate arranged on the front surface of the fixing frame, thereby making the
outward appearance of the wiring assembly look good [2], [3].

Installation habits of wiring devices vary across the world based on different
requirement criteria. Wiring devices are mounted either vertically or horizontally on
to concrete, wooden and plastic walls. Different installation practices and habits make
use of a wide range of installation systems. Based on all these conditions and
requirements, it is therefore desirable to have universal fixing frames for all kinds of
installation practices designing fixing frames for keeping the installation time and
costs of manufacturing minimum and with new architecture to challenge the existing.
Hence, there is a need to understand the architecture of the enclosures for different
markets and the terminology associated through a sample repository. Architectural
comparison of different world markets is done based on the installation habits,
number of parts interacting, variants in each parts interacting (in the architecture),
installation time and cost, and other distinguished features [1].
Figure 1.2 Fixing frame [1]; Courtesy: Schneider Electric
1.2.2 MARKET RANGE AND SEGMENTS
The different wiring device markets around the world are:
MODULAR: In this market segment, each wiring device component is manufactured
and sold separately. It is in use in countries like France, Spain, Belgium and
Portugal.
NORDIC: The assembly methods and wiring devices components are different from
that of modular market. The components are integrated rather than modular in this
market segment. It is in use in Nordic countries like Norway, Greenland, Iceland
and Sweden.

CE 60: This is also more like Nordic architecture where components are integrated.
The CE 60 market ranges in countries like Spain and Germany.
SWITZERLAND: The assembly methods and products of the wiring device
architecture are different from the rest. As the name itself suggests it is marketed in
regions in and around Switzerland.
U.K: The products here are marketed in U.K. nations. Again the assembly methods
and components vary accordingly to the use and requirements.
LATAM: It goes with the market range expanding in Latin America regions.
DENMARK: As the name itself suggests, the wiring device products are marketed
for the use in regions of Denmark.
INDIA, US and ASIA are other market segments.
MARKET RANGE
The standard market ranges are as follows:
ECO: This refers to the low end market range where the products are made of low
quality material composition of less aesthetic appeal and which costs low. It is
targeted to that sector of the society who can only afford to install Eco range products
in houses, motels and small shops.
STANDARD: This is more slightly standard and durable in terms of the quality of the
product. The aesthetic appeal is also quite attractive. This market range is implied to
average and middle class people of the society. It is also installed at places like
houses, buildings, hotels and showrooms.
MEDIUM: This market range targets customers who belong to the above average and
high class of the society. These products are of good quality and more attractive in
terms of aesthetic appeal and durable. It is slightly on the costlier side when it comes
to the use for household purposes.

HIGH: This market segment aims to sell its products to business class. Here the
quality and the material that is made use for the products are very expensive. These
products are mostly used in industries, hotels, bungalows and official places.
LUXURY: This is the highest market segment that promotes its products to only
special purposes and places. It is more designer made and customized products which
make use of actual materials like leather, metal and stones. These are available in
limited quantity and are very expensive which are not recommended products for sale.
These are produced only on orders placed for special occasions.
1.2.3 STUDY AND ANALYSIS OF MODULAR MARKET
Modular design, or "modularity in design", is an approach that subdivides a system
into smaller parts (modules or skids) that can be independently created and then used
in different systems to drive multiple functionalities. A modular system can be
characterized by the following:
1). Functional partitioning into discrete scalable, reusable modules consisting of
isolated, self-contained functional elements
2). Rigorous use of well-defined modular interfaces, including object-oriented
descriptions of module functionality
3). Ease of change to achieve technology transparency and, to the extent possible,
make use of industry standards for key interfaces.
Modular design is an attempt to combine the advantages of standardization (high
volume normally equals low manufacturing costs) with those of customization. A
downside to modularity is that modular systems are not optimized for performance.
This is usually due to the cost of putting up interfaces between modules [1].
1.2.4 MODULAR DESIGN OF WIRING DEVICES
A wiring device product range is modular when:

a) The inserts are not limited to be installed in just one type of fixing frame.
b) The inserts are sold together with the corresponding centre plate.
c) The size of the inserts is: 1 module 22.5x45mm, 2modules 45x45mm.
(International modular), 1 module 25x50mm, 2 modules 50x50mm (Italian
modular) as shown in the Fig 1.3.
d) The cover frame clipping is independent from the centre plate [1].
Figure 1.3 Standard switches [1]; Courtesy: Schneider Electric
1.2.5 MODULAR PRODUCT
Here in this system, the function is linked to the rocker and it is snapped to the fixing
frame. The fixing frame is screwed to the installation box. The aesthetic cover frame
is snapped to the fixing frame.The assembly of modular product is as shown in the
Fig. 1.4 [1].
Figure 1.4 Modular product [1]; Courtesy: Schneider Electric

The components of the modular assembly are as follows:
a) Cover frame: It is also called the aesthetic cover frame or decorative
frame. It is the part of the assembly which is snapped to the technical
fixing frame along with the inserts. It is more variable in terms of its color
and design. It comes in various vibrant colors and adds to the beauty and
aesthetic appeal of the design as shown in the Fig. 1.5 [1].
Figure 1.5 Cover frames [1]; Courtesy: Schneider Electric
b) Central plate or Rocker: This is the part of the enclosure assembly which
covers and protects the actual live functional parts in the assembly. This is
the part which is the upper portion of the function or the insert as shown in
the Fig 1.6 [1].
Figure 1.6 Central plate [1]; Courtesy: Schneider Electric

c) Insert or Function: The function or the insert as the name itself suggests
is the actual functional part of the assembly which carries live current and
does the function of as a switch or a socket as shown in the Fig 1.7. It is
snapped to the fixing frame [1].
Figure 1.7 Functions- Switch and Socket [1]; Courtesy: Schneider Electric
d) Fixing Frame: It is called the technical fixing frame. This part acts as an
intermediate bridge between the installation box in the wall (from which
wires are drawn) and the inserts or function and to the aesthetic cover
frame. The fixing frame as shown in the Fig. 1.8 is screwed or clawed
tightly to the installation box in the wall and the functions or inserts are
snapped to it. The aesthetic cover frame is also snapped to it [1].
Figure 1.8 Fixing Frames [1]; Courtesy: Schneider Electric
e) Intermediate part or Inner Rocker: Sometimes there is also one more
part introduced between the insert and the fixing frame as shown in the Fig
1.9. It is used to give extra protection to the function or insert and keep it
more stable. Just like central plate or rocker this is one more component
between them which is snapped to the aesthetic cover frame [1].

Figure 1.9 Inner rocker [1]; Courtesy: Schneider Electric
f) Paint protector: This is a temporary protective cover that is snapped on to
the inserts during the time of installation as shown in the Fig 1.10. First the
wiring devices are fitted and then the wall is painted. So this component is
used to protect the inserts or functions from any kind exposure or reaction
to the chemical compounds during painting of the walls [1].
Figure 1.10 Paint protector [1]; Courtesy: Schneider Electric
g) Box: More commonly referred to as installation box as shown in the Fig
1.11. This component goes into the wall. This component holds the inserts
along with the fixing frame. The electrical wires are drawn from the wall
into these boxes and connected to the functions. Depending on the types of
walls like concrete, POP or wooden different types of installation boxes
are used.

Figure 1.11 Different types of installation boxes [1]; Courtesy: Schneider Electric
1.3 CLASSIFICATION OF FIXING FRAMES
Fixing frames: Architecture that holds, guides and protects the insert and provides
aesthetic appeal as an assembled range.
Fixing frames are categorized based on material, fixation and applications.
1.3.1 BASED ON MATERIAL
• Plastic FF: Figure 1.12 shows the fixing frame made of plastic material called
PBT (polybutylene teraphtalene). It is a polymer with 30% glass filled.
• ZAMAK FF: Figure 1.13 is a fixing frame made of an alloy constituting Zinc
and Aluminum. Its composition is 96% Zinc and 4% Aluminum. Various
grades of ZAMAK materials like Z1, Z2, Z5, etc are available based on the
types of uses [20].
• Sheet metal FF: This type of fixing frame is made of sheet metal material
usually Aluminum, Brass or Copper as shown in the Fig 1.14 [1].

1.3.2 BASED ON FIXATION
• Screw fixing: Figure 1.15 shows fixing frame which is mounted to the
installation box with the help of screws. The screw series are chosen according
to the holes in the FF and the type of installation boxes used.
• Claw fixing: Figure 1.16 shows the fixing frame which is provided with the
claws that are fixed to the installation boxes [1].
Figure 1.15 Screw fixing FF [1] Figure 1.16 Claw fixing FF[1]
Courtesy: Schneider Electric
1.3.3 BASED ON APPLICATION
• 1 gang / 2 modules FF: Here only one switch or a socket or any other type of
wiring device can go into the fixing frame with the dimension of the slot
opening for inserts in the fixing frame limited to 45x45. It can also
accommodate 2 modules of inserts having dimensions 22.5x45 as shown in the
Fig 1.17 from top left.
Figure 1.14 Sheet metal FF[1]Figure 1.12 Plastic FF [1]
[1] Courtesy: Schneider Electric
[1]
Figure 1.13 ZAMAK [1]
FF[1]

• 2 gang/4 modules FF: This type of fixing frame can accommodate two
switches, sockets or any other type of wiring devices with the dimension of the
slot opening for inserts in the fixing frame limited to (2x)45x45. It can also
accommodate 4 modules of inserts having dimensions 22.5x45 as shown in the
Fig 1.17.
• 3 gang/6 module FF: Here three switches, sockets or any other type of wiring
devices can go into the fixing frame with the dimension of the slot opening for
inserts in the fixing frame limited to (3x)45x45. It can accommodate 6
modules of inserts having dimensions 22.5x45 as shown in the Fig 1.17.
• 3 module FF: This type of fixing frame can accommodate three switches and
any other type of wiring devices with the dimension of the slot opening for
inserts in the fixing frame limited to (3x)22.5x45 as shown in the Fig 1.17.
• 2 gang vertical 71mm FF: This type of fixing frame can accommodate two
switches, sockets and any other type of wiring devices vertically with pitch
distance between the inserts at 71mm as shown in the Fig 1.17.
• 3 gang FF (Multigang): Here there are multiple rows of slots in the fixing
frame to accommodate more number of wiring devices. This FF can hold 3
wiring devices having dimension 44.5x44.5 or 6 of them with dimensions
22.5x44.5 as shown in the Fig 1.17.
Figure 1.17 Different types of FFs based on application [1]; Courtesy: Schneider Electric

1.4 LITERATURE REVIEW
1.4.1 WORK ON APPROACHES TO A PRODUCT DEVELOPMENTAL
PROCESS
Karl T Ulrich et.al., [2] explained the perspectives of marketing, design and
manufacturing into a single approach to product development. Development process
in any organization start with product planning and identifying customer needs. After
that, product specifications are decided simultaneously with concept generation of the
product. Sketches of the various concepts need to be generated before a structured
method of concept screening and concept scoring is applied. Pugh matrix is generated
for the concepts and based on decision criteria appropriate concept is selected for
further testing. The application of structured methods to product development is
highlighted which facilitates the study and improvement of development process.
1.4.2 PRIOR ARTS/PATENTS WORKS
Toru Honda et.al.,[3] invented a fixing frame for a wiring device which included a
metal- made frame body formed into a frame shape having a central opening portion.
The frame body was configured to hold the wiring device with a portion of the wiring
device inserted into the opening portion. The fixing frame further included a resin-
made sleeve provided in the frame body.
The sleeve was configured to engage with an engaging claw of a decoration plate
attached to a front surface side of the frame body. This invention provided a fixing
frame for a wiring device, which was capable of reducing the protruding dimension of
a wiring assembly from an installation surface and restraining the engaging claws of a
decoration plate from being cut away.
Sadamasa Tanaka et.al.,[4] invented a wiring-device mounting structure wherein
outer decorative and inner laying plates was coupled to each other through relatively
short, hooked engaging projections. So till now a mounting frame made integral with
a wiring device was fastened with screws to a box embedded in a building wall and a
decorative plate is screwed to the mounting frame. However, this structure has had
such a problem that the screws for securing the decorative plate to the mounting frame

have to be left as exposed on front face of the decorative plate to render its appearance
unfavorable. As a result, coupling means comprising of small engaging projections in
the form of snaps were provided on the surface of the fixing frame.
Dennis A. Oddsen et.al.,[5] invented fixing frame which overcame the difficulties
encountered with respect to mounting electrical wiring devices to a common box and
then positioned the devices relative to each other prior to attaching a wall plate. Some
of the difficulties encountered were positioning the wiring devices to be aligned with
each other, locating the wiring devices to be parallel to each other, adjusting the
spacing between the different devices to be equal and uniform and fixing all of the
devices against the wall. The alignment pins, when engaged by the close clearance
locating openings, accurately positioned the wiring devices to allow a wall plate to be
placed around the wiring devices without requiring any initial or subsequent
adjustment. Each set of alignment pins on the alignment plate can be located on a
vertical axis which accurately defines the centre for the wiring device. The opening in
the wiring device receives and holds captive a set of alignment pins. The alignment
pins accurately position, align and locate all of the wiring devices mounted to the
alignment plate, and the plate allows the wiring devices to be positioned against a
surface.
1.4.3 RESEARCH STUDY ON SNAP DESIGN
Suat Genc et.al.,[6] explained a traditional integral snap-fit which focused almost
exclusively on the individual locking features, such as cantilever hooks, compressive
hooks etc. The positioning and orientation of other significant features on parts, such
as those that facilitate or enhance engagement and eliminate unwanted degrees of
freedom left by locking features. This invention builds on relatively new
methodologies and guidelines for arranging all attachment features on plastic parts
comprising snap-fit assembly. Classification of features into categories of locking
features, locating features and enhancements of these is used as the basis of
discussion. A systematic approach attachment design is presented. This paper
explained that integral attachment features are formed into parts to enable mechanical
joining of those parts by: i.Establishing part location, alignment and orientation; ii.

Eliminating degrees of freedom and/or absorbing tolerances between the parts; iii.
Locking the parts into an assembly; and iv. Transferring service loads.
Yi-Ho Chen et.al., [7] proposed a design to alleviate the requirement for precise
interference and to improve the assembly's robustness. The author reported a constant-
force snap-fit mechanism that maintains a regular mating force against a range of
interference uncertainty. Illustrated simulations and experiments showed that the
mating force of the constant-force snap-fit is less sensitive to interference uncertainty
than are typical snap-fits. Since uncertain mating force was minimized without
demanding precise interference, this mechanism was to provide a ready alternative to
existing snap-fit assembly applications. The use of snap-fits relied on accurate
calculation of interference and the associated mating force. The mating force was
proportional to the interference, which was very sensitive to plastic part dimensional
error. Insufficient interference would result in loose assembly, whereas excessive
interference would impede assembly and possibly damage the thin-walled plastic
parts.
1.4.4 RESEARCH STUDY ON PROTOTYPING TECHNIQUES
Ludmila Novakova-Marcincinova, [10] reported the principle of Fused Deposition
Modelling method and production of parts. Fused Deposition Modeling (FDM) was
developed by Stratasys in Eden Prairie, Minnesota. This printer used as building
material thermoplastic ABSplus Ivory which comes in standardized packages as fiber
with a diameter of 1.6 mm rolled onto a reel. Each spool contained 500 cubic
centimeters of material. The support material used was resin Soluble SR-P400 which
comes in the same package as a building material. After printing the prototype it was
necessary to clean the prototype of the auxiliary material The parameters on which the
building of prototype depends are (1) Bead width; (2) Air gap; (3) Model build
temperature; (4) Raster orientation; (5) and color.
1.4.5 RESEARCH STUDY ON THERMOPLASTIC DESIGN AND MOULDS
Merlin Gerin, [17] reported that considerable thought should be put into the
design of moulded parts and their moulds, to ensure that the parts will not be trapped
in the mould, that the moulds can be completely filled before the molten resin

solidifies, and to minimize imperfections in the parts, which can occur due to
peculiarities of the Design Process. The material type to be considered, design
considerations and guidelines have also been explained.
G Lancon, [18] defined a certain number of rules for the design of thermoplastic
parts. Compliance with these rules guarantees the performance of the moulded part.
The main rules are i. Choice of material; ii. Part plotting rules; and iii. Main
implementation rules. These set of rules were considered essential affecting the
behavior of the moulded parts which ultimately defines the effectiveness of the parts
or components in terms of assembly, disassembly and functioning productivity. It was
therefore considered significant and pivotal in defining the thermoplastic design rules
before manufacturing the components.
Marcel Dekker, [19] proposed that DFMA can be considered at all stages of the
design process. The design for manufacturing guidelines provided information while
designing, the designer should reduce the cost and difficulty of manufacturing a
product, and while developing a modular design keeping in mind that the part should
be multi-functional or multi-use and to avoid separate fasteners and minimizing
assembly directions to minimize handling time.
1.5 MOTIVATION
From the literature review [2-19], it is evident that some of the researches have
focused on designing the fixing frame for a wiring device dedicatedly for horizontal
installation. Some of the difficulties encountered included positioning of wiring
devices aligned with each other, space adjustment between different wiring devices,
and fixing the devices against the wall. This necessitates the design of universal fixing
frame which could be flexible for both horizontal and vertical installation. Hence the
current project focuses on design and development of universal fixing frame for
modular market. Various concepts are developed and evaluated through Pugh’s
method. 3D models of the concepts are realized by using prototyping technique.
Structural analysis is carried out to analyze the stress distribution and strength
carrying capacity.

1.6 COMPETITOR PRODUCT ANALYSIS
Competitor analysis in marketing and strategic management is an assessment of the
strengths and weaknesses of current and potential competitors. This analysis provides
both an offensive and defensive strategic context to identify opportunities and threats.
Competitor analysis is an essential component of corporate strategy.
1.6.1 TEARDOWN ANALYSIS OF COMPETITOR FIXING FRAME
A teardown analysis of the competitor product was initially done to understand the
solution provided by the competitor company “Legrand” for the horizontal and
vertical installation practices. Here a bridge is provided at the places where vertical
system is required. The bridge is also snapped to the fixing frame like an insert. It is
not an integral part of the fixing frame, which is only used when vertical installation is
required. The entire snapping mechanism of the bridge to the fixing frame is patented
by Legrand.
Figure 1.18 Teardown analysis competitor fixing frame; Courtesy: Legrand
Some of the observed features and characteristics as shown in the Fig 1.18 are as
follows:
 Self centering of sheet metal part inside the fixing frame mould.
 Binding of the sheet metal ejector points, injection Points in the fixing frame.
 Locking mechanism to avoid transversal sliding in the fixing frame.
 Sheet metal supports to avoid deflection in the fixing frame.
 Sheet metal orientation at claw leg in the fixing frame.
 Fixing frame should be able to withstand a maximum pull out force of 20kg.

The functions of the fixing frame are as follows: Figure 1.19, Figure 1.20 and Figure
1.21 respectively shows one fixing frame to fix 4 modules horizontally at 57mm
pitch, 71mm pitch and vertical 71mm by changing orientation of inserts.
Figure 1.19 Fixing Frame to fix 2 gang/4 module inserts at 71mm pitch horizontal [1].
Figure 1.20 Fixing Frame to fix 2 gang/4 module inserts at 57mm pitch horizontal [1].
Figure 1.21 Fixing Frame to fix 2 gang/4 module inserts at 71mm pitch vertical [1].

1.7 PROJECT OBJECTIVES
The main objectives of this current project work are:
1. To study and analyze the wiring device Modular architecture.
2. To develop new design concepts for the fixing frame using FBD (Functional Block
Diagram) and FMEA (Failure Mode Effects Analysis) tools that provides a universal
and standard solution for both horizontal and vertical installation practices.
3. To realize the design concepts of the fixing frame using 3D modeling techniques
and to perform structural analysis on the finalized design concept.
1.8 PROJECT METHODOLOGY
In order to accomplish the above listed objectives, the following methodology is
scheduled for three main phases. The methodology followed for each phase is
explained:
PHASE-I: UNDERSTANDING WIRING DEVICE ARCHITECTURE
 Understanding different market segments
There is a need to understand different market segments of markets and product range
in each of these markets. The products in the different market segments analyzed were
CE 60, Nordic, LATAM, Denmark and Asia.
 Understanding terminology and knowing components in the architecture
hands-on
Once the different market segments and product range in each of these are
understood, the different terminologies used in different markets for different
components in the WD architecture are necessary to understand.
 Building Sample Repository for Analysis and tagging
A sample repository of the products and the components in the architecture are
collected for different market range and the distinguishable features in each of these

products are analyzed and all the collected samples are categorized under respective
heads by tagging.
 Summary
A detailed summary of each of these activities are summarized for future reference
and documentation.
PHASE-II: ANALYSIS OF MODULAR MARKET
 Functional Block Diagram (6 sigma tool) and Failure Mode Effects
Analysis
The functionality of each component in the assembly is clearly defined for the
existing architecture in the modular range. The different interactions between each
component in the assembly are detailed out. The possible failure modes are addressed
and analyzed through FMEA keeping the design aspects into consideration.
 Exhaustive analysis of each parameter impacting the given interaction
The parameters impacting the given interactions which were detailed out in FBD are
analyzed which further gives a basis for designing the fixing frame as per
specifications.
 Understanding the Design Guidelines
It is important to understand the Design Guidelines which have been already
specified for the design of fixing frames. A set of guidelines and procedures are
detailed out in the Design Guidelines which are to be strictly adhered and followed.
PHASE-III: DEVELOPING INNOVATIVE NEW ARCHITECTURE
(SYSTEM LEVEL) TO CHALLENGE THE EXISTING DESIGN
 Research and Proposals
The internal and external search for the design purpose is done with the available data
to get a fair idea as to how the design concepts for the problem statement are being
developed and also the kind of work that already exists and also been carried out so

far. The research work and patent work done so far on the problem definition are
reviewed.
 Concepts and 3D Modelling
The concept generation process begins with sketches, 3D modelling and description
on the concepts. Further the best concept is selected to go ahead with the actual design
and prototyping by making use of concept screening (PUGH MATRIX) and concept
scoring (DECISION MATRIX) by concept selection process.
 Prototyping
Rapid prototyping technique is used to realize the design concepts and to get a first
hands-on feel of the proposed concepts. Further basic verification and validation for
the design concepts using the prototype is done by performing few standard fits and
tolerances tests on them.
 Analysis
Structural analysis is performed on the design to validate the theoretical design
calculations. The analysis results for stress distribution, strength and stress
concentration factor are compared for existing design analysis results of the fixing
frame.
 Conclusions
Finally, the data from the design calculations, testing results and analysis results are
documented for the new fixing frame. The technical specifications and CAD drawings
are published for future modifications, reference and use when it is put into
production. The design work is concluded with results and discussion, and with
providing scope for future work.

1.9 STAGE–GATE MODEL
A Stage–gate model, also referred to as a phase–gate process, is a project
management technique in which an initiative or project (e.g., new product
development, process improvement, business change) is divided into stages or phases,
separated by gates. At each gate, the continuation of the process is decided by
(typically) a manager or a steering committee. The decision is based on the
information available at the time, including the business case, risk analysis, and
availability of necessary resources (e.g., money, people with correct competencies).
A Stage-Gate® process is a conceptual and operational map for moving new product
projects from idea to launch and beyond – a blueprint for managing the new product
development (NPD) process to improve effectiveness and efficiency. Stage-Gate is a
system or process not unlike a playbook for a North American football team: it maps
out what needs to be done, play by play, huddle by huddle – as well as how to do it –
in order to win the game. Stage-Gate®
is a value-creating business process and risk
model designed to quickly and profitably transform an organization’s best new ideas
into winning new products. When embraced by organizations, it creates a culture of
product innovation excellence – product leadership, accountability, high-performance
teams, customer and market focus, robust solutions, alignment, discipline, speed and
quality. The Stage-Gate model is based on the belief that product innovation begins
with ideas and ends once a product is successfully launched into the market. This has
a lot to do with the benchmarking research that the Stage-Gate model design is
premised on, and is a much broader and more cross-functional view of a product
development process. The Stage-Gate model takes the often complex and chaotic
process of taking an idea from inception to launch, and breaks it down into smaller
stages (where project activities are conducted) and gates (where business evaluations
and Go/Kill decisions are made).
The project methodology which was scheduled for 3 phases has to go through 4
different stages. And at the end of each stage, the progress is evaluated by gates and
which also defines the work carried out. Hence the project methodology is depicted in
a simplified version using a Stage Gate Decision Making diagram as shown in the
Fig. 1.22.

1.10 OUTLINE OF THE PROJECT
The project report is organized into six chapters. The outline of the project report is
explained as follows:
Chapter 1: gives introduction to the Enclosures and Wiring devices by explaining the
products and their description, study of market range and segments and modular
design of wiring devices. It explains the types of fixing frames by giving a brief
classification. It deals with the literature review for the design work. It also highlights
the objectives and methodology followed in the project work.
Chapter 2: deals with the conceptual design of the fixing frames. It explains each and
every concept by providing a brief description to it supported by 2D and 3D models.
It explains the concept scoring and concept screening processes by Pugh Matrix and
Decision Matrix.
Chapter 3: involves the detailed design work which includes calculations for the
fixing frame and for snapping. It explains the design of the fixing frame by providing
analysis results to validate the theoretical design work. It also deals with the tolerance
analysis results for the fixing frame.
Chapter 4: deals about the prototyping techniques by Fused Deposition Modeling
and the methodology followed in prototyping. It shows the prototypes for all the
concepts developed for the design of fixing frames.
Chapter 5: deals with the results the discussions part of the design work. It deals with
the standards achieved through the design process and the effects and influence of
using the sliding bridge in the fixing frame. Further, it deals with the methods to avoid
the strength reduction in the fixing frames when using the sliding bridge.
Chapter 6: summarizes the design and development process by highlighting the
objectives and goals achieved. It sheds light on the scope of work to be carried out in
future by keeping design considerations for all types of standard enclosures available
in the market and the manufacturing constraints.
The detailed summary of the introductory chapter is discussed in the next section.

1.11 SUMMARY
This chapter has therefore provided an introduction to the various domains covered
in this project as well as relevant information regarding the same. Customer needs
were identified and evaluated. The enclosure and wiring devices were described in
terms of product description. The market segments and market ranges were described
for the wiring devices. The study and analysis of modular market was successfully
completed. The components in the modular market were described and various
terminologies associated with the modular market were understood. Comprehensive
classification of the fixing frames was done based on different criteria.
The key benefits of the methodology followed were: ensuring that the product is
focused on the customer needs and that no critical customer need is forgotten;
developing a clear understanding among members of the development team of the
needs of the customers in the target market; developing a fact base to be used in
generating concepts, selecting a product concept, and establishing product
specifications; and creating an archival record of the phases of the development
process.
This chapter provided an extensive literature survey about the background of the
field in which research is conducted and the motivation to the project, as well as
introduced various objectives, aims and overview of the entire project, while setting
the tone for the rest of the detailed phases conducted through the project. The
conceptual design, detailed design, prototyping and testing, results and discussions,
conclusions and future scope of work are discussed in the following chapters.

CHAPTER-2
2.0 CONCEPTUAL DESIGN OF FIXING FRAMES
The concept generation process begins with a set of customer needs and target
specifications and results in a set of product concepts for which a team will make a
final selection. In most cases, an effective development team will generate hundreds
of concepts, of which 5-20 will merit serious considerations during the subsequent
concept selection activity.
This chapter deals with product design specifications in which various parameters of
the fixing frame design are described. The concept generation process is described,
followed by concept selection. In this project three most feasible design concepts of
the fixing frame have been presented and the best concept is selected through the
concept selection process.
2.1 PRODUCT DESIGN SPECIFICATIONS
The product design specification (PDS) is a listing of the critical parameters,
specifications and requirements for the product to be designed. It is aimed at ensuring
that the subsequent design and development of a product that meets the needs of the
user. Product design specification is one of the elements of product lifecycle
management. Product specifications are formulated by analyzing the existing fixing
frame and the dimensions of the inserts.
These dimensional details are used to create the 3-D models of the concepts.
Table 2.1 Product design specifications and characteristics
Parameter Specification
1. Product or component type Rectangular fixing frame
2. Number of modules 8 modules
3. Number of gangs 1 gang
4. Fixing mode Screws

5. Pitch between inserts 57 mm, 71mm
6. Window length for inserts 180 mm
7. Window breadth for inserts 44.5 mm
8. Screw hole diameter 3 mm
9. Screw type series 1.8 T
10. Overall length of fixing frame 225 mm
11. Overall breadth of fixing frame 70.5 mm
2.2 CONCEPT GENERATION
The concept generation stage of product development is where the skill, experience
and creativity of IDC’s design team are used to generate designs which address the
identified needs of the clients and the users to create a ‘wow factor’. Ideas are like
prototypes - they need to be tested to verify they fit customer and client needs. Once
concepts are generated, it can be presented in a variety of formats to enable full
understanding and evaluation of the concepts.
A product concept is a description of the technology, working principles, and form of
the product.
Concepts are expressed as:
a. Sketch
b. 3-Dimensional model (Pro/E is the modeling software package used.)
c. Brief textural description
Here we discuss three concepts which are devised based on the requirements and the
effectiveness of its use.
2.2.1 CONCEPT-1: SLIDING BRIDGE
a). Sketch: Fig.2.1 shows the fixing frame sketch with slots for sliding the bridge and
Fig. 2.2 shows the bridge component which slides in the slots provided in the FF.

Figure 2.1 Sliding bridge concept
Figure 2.2 Bridge component concept
b). 3-D model: The 3-D models of the fixing frame and the bridge are shown in fig
2.3 and fig 2.4 respectively. And the 3D assembly of the sliding bridge concept is
shown in the Fig. 2.5.
Figure 2.3 3D model of fixing frame for sliding bridge concept

Figure 2.4 3D model of bridge component
Figure 2.5 3D assembly of concept-1
c). Concept description: This design concept has a “sliding bridge” which is flexible
in terms of its mode of operation and use. It can both used as an integral part of the
fixing frame or as a non-integral part of the fixing frame. It is inserted from the side of
the fixing frame in the space provided for sliding. The sliding bridge slides in the
fixing frame and stopped at the ends of the window opening and it is stopped at
specified distance from the ends of the window where the inserts can snapped on to
the fixing frame vertically.
2.2.2 CONCEPT-2: MUTUAL FIT AND SNAPPING
a). Sketch: Fig. 2.6 shows the fixing frame sketch with mutual fit and snapping
patterns on it and the Fig. 2.7 shows sketch of an insert with mutual fit and snapping
patterns.

`
Figure 2.6 Mutual fit and snapping concept
Figure 2.7 Insert for mutual fit and snapping
b). 3-D model: Fig. 2.8 and Fig. 2.9 show the fixing frame and the inserts with
mutual fit and snapping patterns.
Figure 2.8 3D model of a FF for mutual fit concept

Figure 2.9 3D models of 1 module and 1 gang inserts
c). Concept description: This concept involves the design pattern and structure that
are similar in both the fixing frames and the inserts. The cylindrical sliding pattern to
restrict the horizontal movement of the inserts inside the fixing frame and the
snapping patterns to restrict the vertical movement are alternated in sequence so that it
mutually matches in both inserts and the fixing frame. The distances for the placement
and location of these alternating patterns in sequence are calculated in such a way that
the insert can fit into the fixing frame both vertically and horizontally.
2.2.3 CONCEPT-3: ROTATING BRIDGE
a). Sketch: Fig 2.10 and Fig. 2.11 shows the sketches of the fixing frame and the
rotating bridge component respectively.
Figure 2.10 Rotating bridge concept

Figure 2.11 Rotating bridge component
b). 3-D model: Fig. 2.12 and Fig. 2.13 shows the 3-D models of the rotating bridge
concept.
Figure 2.12 3D model of a FF for rotating bridge concept
Figure 2.13 3D model of rotating bridge component
Fig. 2.14 and Fig. 2.15 show the assemblies of the rotating bridge component with the
fixing frame.

Figure 2.14 3D assembly of concept 3 (position-1)
Figure 2.15 3D assembly of concept 3 (position-2)
c). Concept description: This design concept has a rotating bridge which is screwed
as a part of the fixing frame on the lower surface. The two positions of the bridge are
as shown in the above figure. When vertical installation is required the bridge is
rotated and snapped on to a similar component on to which it is screwed on the other
opposite end of the fixing frame. The inserts can then be snapped on to the bridge on
one side and to the fixing frame on the other side for vertical installation.
Therefore, all the fixing frame concepts are clearly explained through conceptual
sketches, 3D modeling and brief textural description. The next step is to understand
the general assembly techniques of the enclosure components for all the design
concepts of the fixing frame.

2.3 GENERAL EXPLODED VIEW FOR ALL ENCLOSURE ASSEMBLIES
The exploded view in the technical drawing of the enclosure assembly shown in the
Fig.2.16 shows the relationship and the order of assembly of various parts. It shows
the components of the enclosure assembly slightly separated by distance, or
suspended in surrounding space in this case of a three-dimensional exploded
diagram. It shows all parts of the assembly and how they fit together. In this
mechanical system, the components closest to the center are assembled first, or the
main part in which the other parts get assembled. This drawing also represents the
disassembly of parts, where the parts on the outside normally get removed first.
The general assembly methods were earlier discussed in modular product description
in chapter 1. The components in the modular assembly for all the three concepts
remain the same. The enclosure components are similar in all the concepts for the
entire assembly, except for the inserts in case of “Mutual Fit and Snapping” concept.
The installation box is first installed to the wall, followed by screwing of the FF to the
box. The inserts are then snapped to the FF. Only in case of vertical installation for
“Sliding Bridge” and “Rotating Bridge” concepts the bridge component is introduced.
The cover frame and the aesthetic cover frame are then snapped to the fixing frame,
which completes the assembly methods in all the concepts. Fig. 2.16 shows the
general assembly of an enclosure.
Figure 2.16 General Exploded View for all Enclosure assemblies

2.4 CONCEPT SELECTION
Concept selection is the process that narrows down a large list of components into one
final design. A concept screening and concept scoring matrix are the two methods
utilized by the team to complete this stage. It is a convergent process and an iterative
process that does not always produce the dominant concept immediately.
Two Stages of Concept Selection:
1. Concept screening
• Reduce the many product concept ideas generated to a relative few that will get
additional refinement and analysis.
2. Concept scoring
• Use objective methods to select to your consensus final concept selection.
2.4.1 PUGH’S METHOD
Pugh Concept Selection is a quantitative technique used to rank the multi-
dimensional options of an option set. A basic decision matrix consists of establishing
a set of criteria options which are scored and summed to gain a total score which can
then be ranked. Importantly, it is not weighted to allow a quick selection process.
A weighted decision matrix operates in the same way as the basic decision matrix but
introduces the concept of weighting the criteria in order of importance. The resultant
scores better reflect the importance to the decision maker of the criteria involved. The
more important the criteria the higher the weighting it should be given. Each of the
potential options are scored and also multiplied by the weighting given to each of the
criteria in order to produce a result.
The advantage of the decision making matrix is that subjective opinions about one
alternative versus another can be made more objective. Another advantage of this
method is that sensitivity studies can be performed. The decision matrix provides
means of comparing and evaluating concepts. The method gives insight into strong
and weak areas of the concepts. The feasibility of the concepts is based on the design
team’s knowledge. It is often necessary to augment this knowledge with research and
development of simple models [2].

2.4.2 KEY CRITERIA CONSIDERED FOR CONCEPT SCREENING AND
CONCEPT SCORING
Here is the list and description of each criterion and how it affects the concept
selection process of the fixing frames. Each criterion is given a specific weightage and
it is been clearly defined in the concept scoring and concept screening methods.
a) Modular: The number of functional elements which can be disassembled and
assembled in a similar way, and which can independently partitioned, scaled
and reused.
b) Ease of manufacturing: The ease with which each of these components in the
modular architecture can be manufactured and put into production with no
manufacturing constraints.
c) Ease of assembly and disassembly: The ease with which these components
in the architecture can be disassembled and assembled, and the order in which
the assembly and disassembly takes place should be same and without much
complexity.
d) Less number of parts: The number of parts in the architecture should be as
low as possible. The DFA Guidelines are referred to reduce the number of
parts.
e) Simplicity of design: The design should be simple in its way of construction
and operation. Simpler the design, lesser the manufacturing costs and lesser
the installation time.
f) Cost: The cost of each of these components sold individually or as an
assembly should be as low as possible. This again goes with the simplicity of
the design.
g) Strength: The strength and the bearing capacity of the design should be on
the higher side to withstand the impact and the stress it takes.
h) Flexibility: The assembly of the components in the architecture should be
flexible and it should be in a way which offers more flexible arrangement
combinations as per the needs and requirements.
i) Durability: The product when it is put into use should have more durability
and should have long lasting performance. It should be able to withstand and
bear continuous cycles of loading when it comes to operations.

2.4.3 STEPS INVOLVED IN CONCEPT SCREENING AND CONCEPT
SCORING
Step 1- Select the criteria for comparison
As discussed in the earlier section, the key criteria are selected for comparison. The
list of criteria is developed from the customer needs and engineering specifications.
All team members contributed in making the list. The list is then debated until
consensus is reached.
Step 2- Select the concepts to be compared
The alternatives are those that proceed from the concept generation. It is important
that all the concepts are compared at the same level of abstraction.
Step 3- Generate the score
Benchmark options are selected as a datum. All other designs are compared to it
relative to each need. For each comparison, the concept being evaluated is judged to
be either better than (“+”score), about the same (“s”score), or worse than the datum
benchmark option (“-”score).
Step 4- Compute the total score
Three scores are generated, the number of plus scores, the number of minus scores
and the total. If a concept has a good overall score or a high “+”score, it is important
to notice what strengths it exhibits, that is, which criteria it meets better than datum.
Same for “-”score.
Step 5- Rank the concepts
Once the scores are computed, further the concepts are ranked according to its
credibility based on the weightage for each criterion. Each concept gets a rank based
on the scores. The technical team based on their knowledge and experience also has a
final say in deciding the rank for the concepts.
Step 6- Proceed with concept ranked highest
The concept which gets the highest rank is finalized for future design and
development process. The finalized concept is put into dedicated design work,
followed by prototyping.

2.4.4 PUGH MATRIX
Table 2.2 Pugh Matrix for concept screening
Here, the “Importance Rating” and “Benchmark Options” are clearly defined in
the table. Each concept is given ratings against each criterion. As discussed earlier,
the scores are computed. The sum of positives, negatives and sames are computed for
each concept which is clearly shown in the table. The difference between the
weighted sum of positives and weighted sum of negatives gives the actual score of the
concept. The concept 1-Sliding Bridge gets the maximum score followed by concept
2-Mutual Fit and concept 3- Rotating Bridge.

2.4.5 DECISION MATRIX
Table 2.3 Decision Matrix for concept scoring
The concepts are ranked as per the scores and taking into considerations the point of
views and opinions of the technical team. Here the concept 1- Sliding bridge gets the
highest rank followed by concept 2-Mutual Fit and concept 3- Rotating Bridge. Next
the decision on the concepts are finalized as to which design concept to go ahead
with, and which to drop and which to combine, refine or modify for future scope of
work. Decision matrix helps to combine and integrate the features of the second or
third best concepts. In this case we have only 3 concepts out of which 2 are dropped
and withdrawn. The summary of the conceptual design is discussed in the next
section.

2.5 SUMMARY
The concept generation method presented in this chapter consists of clarification of
the problem, external and internal search, systematic exploration which reflects the
solutions and the process by identifying the opportunities for improvement in
subsequent iterations or future projects. A structured approach to concept generation
is therefore followed which allows active participation of the team members in the
process.
The product specifications were described in order to generate various concepts based
on the requirements. The concept generation process described the concept design of
the fixing frame in terms of brief sketches, 3D models and textural descriptions. The
standard assembly procedures with the enclosure components were discussed for all
the concepts. The Pugh’s method was adopted for the concept selection process. The
best concept for the design of the fixing frame was evaluated using the Pugh matrix
and Decision matrix.
Therefore, at the end of this chapter the concept of the fixing frame has been
finalized. So the next step is to detail out the conceptual design and develop the fixing
frame keeping all the design considerations in mind. This explanation on the detailed
design is described in the following chapter.

CHAPTER-3
3.0 DETAILED DESIGN OF FIXING FRAMES
Advanced graphical and analytical techniques are made use to assess in interpretation
of the existing experimental data. The detailed design is appropriate at several
different points in the development process on judgments made by the development
team.
In this chapter the detailed explanation is given for the Sliding bridge concept. The
physical dimensions have been taken keeping the existing frame as a reference.
ZAMAK is considered as the material for fabrication.
3.1 MATERIAL SELECTION
ZAMAK is an alloy of Zinc, Copper and Aluminum. Die cast Zinc alloys are mainly
characterized by their low melting point and their excellent cast ability (fluidity at
moulding temperature). At high production rates, they allow parts with complex
shapes to be obtained, with reduced dimensional tolerances. The outstanding
mechanical properties, dimensional stability and corrosion resistance have led
designers to find an economic solution in these alloys.
Table3.1 shows the various standards and grades of ZAMAK alloys [20].
Table 3.1 ZAMAK Standardized Designations [20]
Standardised designations Former French
Designation
NF A55-010
NF EN 12844 ISO 301
Numbers Shortened
ZP0400 ZP3 ZnAl4 Z-A4G
(ZAMAK 3*)
ZP0410 ZP5 ZnAl4Cu1 Z-A4U1G
(ZAMAK 5*)
ZP0430 ZP2 ZnAl4Cu3 Z-A4U3G
(ZAMAK 2*)
ZP3 is recommended for the majority of applications. It offers greater dimensional
stability than ZP5. It is more malleable, slightly more corrosion-resistant and retains
good impact strength even after prolonged use at 90°C. ZP5 is sometimes preferred
for its slightly greater tensile strength and hardness when the previous conditions are

not vital. This is particularly the case for friction parts such as bearings, bushings,
contact-holder arms, mounting plates, etc.
Addition of copper to zinc alloy composition ensures increased hardness and,
consequently, very good wear resistance. Zinc alloys exhibit good damping
capacities. For parts subjected to vibrations, it is advised to use of a thin, ribbed line
rather than large thicknesses. This will ensure better metal quality (finer grains, no
porosity), higher inertia (due to the ribs) and fewer stresses (lighter weight).
Table 3.2 shows the main capacities of various ZAMAK alloys.
Table3.2 Main Capacities of ZAMAK Alloys [20]
Alloys Main properties
ZAMAK 2 Recommended for parts with mechanical
functions (gears).
ZAMAK 3 Increased impact strength.
Increased corrosion resistance.
Better sustained dimensional accuracy.
ZAMAK 5 Increased tensile strength as for ZAMAK 2.
Impact strength and dimensional stability.
Corrosion resistance as for ZAMAK 3.
The physical and mechanical properties of Zinc alloy diecast are given in Table 3.2.
Table 3.3 Physical and Mechanical properties of ZAMAK
Property Measurements
unit
ZP3 ZP5 ZP2
Density Kg/dm3 6.7 6.7 6.8
Tensile
strength
MPa 280 330 355
Elastic limit
0.2 %
MPa 200 250 270
Compressive
strength (at
0.1 %)
MPa 450 600 640
Shear
strength
MPa 220 270 317
Young's
modulus
GPa 85 85 85

3.2 DESIGN CALCULATIONS FOR THE FIXING FRAME
The design of the fixing frame is done with the specifications of the existing fixing
frame developed by Schneider Electric. The new design of fixing frame developed
includes an additional bridge part which needs to be structurally analyzed and
validated through design calculations.
3.2.1 THEORETICAL DESIGN CALCULATIONS OF THE BRIDGE
COMPONENT OF THE FIXING FRAME
The bridge can be considered to be a straight beam of rectangular cross-section on
which the following loads are applied.
1. The weight of the insert
2. The maximum pull or push force
(1) SHEAR STRENGTH CALCULATION OF FIXING FRAME
Area on which the load is applied = 2 x (Contact Area of bridge with Fixing Frame)
= 2 x (11.6 x 2)
= 46.4 mm2
The tensile strength of ZAMAK is 269 MPa, therefore shear strength according to
Max Shear Stress theory is half of tensile strength, i.e., 134.5 MPa (269/2).
 Max pull or push force = 22 kgf (Taken as a standard by Schneider Electric)
Shear Stress generated = Maximum Pull out Force x Acceleration due gravity
(Area on which load is applied)
(1)[14]
= 22 x 9.81
46.4
= 4.725 MPa
We know that: F.O.S = Actual Stress (2) [14]
Allowable Stress

Keeping a FOS of 2.5, we get the allowable or design shear stress in the frame as
4.725 x 2.5 = 11.82 Mpa, which is still less than the Shear strength of the ZAMAK
material which is considered.
 Hence the Shear Strength of the fixing frame is within the limits and the
fixing frame will not fail during shearing.
(2) BENDING STRESS CALCULATION OF THE BRIDGE
The 22kgf load acts on the bridge at the snap positions. Hence, this force can be
considered as a concentrated load at the centre of the bridge. The bridge is considered
to be a simply supported beam with a load of 22kgf at the centre. When load will be
applied on the bridge, bending moment acts on the bridge as a result of which bending
stress is generated in the fibers of the bridge. The fibers at the bottom tend to elongate
and are in tension, whereas the top most fiber in the bridge tend to come together
(contract) resulting in compression.
As a result tensile stress is generated above the neutral axis and compressive stress is
generated above the neutral axis. The maximum bending stress in the bridge is
nothing but the tensile stress in the bottom fibers [14].
Using the formula of maximum bending moment, Mmax = (WL/4) which is at the
centre of the bridge.
Here, W = 220N
L = 44.5 mm
Therefore, Mmax = (220x 44.5)
4
= 2447.5 N-mm
Max. Bending Stress = M x c (3) [14]
I
= 2447.5 x 3
405
= 18.12 MPa

Keeping a FOS of 2.5, Allowable Stress = 18.12 x 2.5 = 45.3 Mpa , which is less
than the tensile strength of the ZAMAK material we have considered for the fixing
frame.
 Hence the tensile strength of the fixing frame is within the limits and the
fixing frame will not fail whenever the frame is pushed or pulled.
Fig. 3.1 shows the free body diagram of the bridge assumed as a simply supported
beam with support reactions Ra and Rb.
Figure 3.1 Bridge simulated as a simply supported beam
Figure 3.2 Shear Force Diagram of the Bridge
Figure 3.3 Bending Moment Diagram of the bridge

The Shear Force diagram and Bending Moment diagram are as shown in Fig. 3.2 and
Fig. 3.3 respectively.
3.2.2 THEORETICAL DESIGN CALCULATIONS FOR SNAPPING
Snap Latches: Snaps allow an easy method of assembly and disassembly of plastic
parts. Snaps consist of a cantilever beam with a bump that deflects and snaps into a
groove or a slot in the mating part. Snaps can have a uniform cross-section or a
tapered cross section (with decreasing section height). The tapered cross-section
results in a smaller strain compared to the uniform cross-section. Here we consider the
general case of a beam tapering in both directions. Fig. 3.4 shows the general way of
snap actuation.
The performance of a snap-fit latch greatly depends upon its engineering design.
Snap-fit latches that are not designed properly can break in assembly or even during
moulding or shipping. One of the key design parameters is the amount of strain
caused when the beam is deflected to achieve the snap-fit assembly. There are a
number of issues to be considered while designing a snap-fit latch for a particular
part: The actual strain level which will be acceptable in any given design depends
upon a number of factors e.g. fiber orientation, distance from gate, and weld-line
location. Fig.3.5 shows the overlap to be considered while designing a snap-fit latch.
Figure 3.4 Snap Actuation Figure 3.5 Overlap in snaps

The deflection for snaps in the inserts is calculated to provide the dimension for the
overlap that is needed for the interface between the fixing frame and the insert for
proper snapping. The amount of overlap provided for snapping is directly proportional
to the deflection of the snaps in the insert material [6].
The calculation of the deflecting force for snaps in the inserts also serves the same
purpose. The amount of overlap given should be so much such that it withstands the
deflecting force without breakage and failure at the points of snapping. The regions of
snapping are the most important regions where entire load is concentrated while
performing the pull out and push in tests of the inserts. The amount of overlap given
and interface for proper snapping of the inserts to the fixing frame is determined by
these two parameters.
Figure.3.6 shows the dimensional details of the snap.
Fig.3.6 Dimensions of the snap [6]
The following formulae can be used to calculate maximum allowable deflection ‘y’
and deflection force ‘Fb’ for a tapered cantilever beam with rectangular cross-section.
The height of the beam decreases linearly from t1 to t2 as shown in the Fig 3.6.
y =c . 2.L2
. έ (4)[6]
3 . t1
F=w . t1
2
. Es . έ (5)[6]
6. L
Where,
Es =Secant modulus =3500 MPa
L =Length of the beam =6.7mm

W =Width of the beam =1.8 mm
t1 =height of the cross section at fixed end of the beam =1.45 mm
t1 =height of the cross section at free end of the beam =.85 mm
C =Multiplier =1.4
The formula for deflection ‘y’ contains a multiplier ‘c’ that depends on the ratio t2/t1,
see Table 3.4 , where t1 is the height of the beam at the fixed end and t2 is the height
of the beam at the free end. The value of c obtained is 1.4.
Table 3.4 Table for determining the Multiplier ‘c’ [6]
t2/t1 .40 .50 .60 .70 .80 .90 1.00
c 1.893 1.636 1.445 1.297 1.179 1.082 1.000
Putting the values in the above formulas we get,
y = 1.4 x 2 x ( 6.7)2
x 0.15 = 4.33 mm
3 x 1.45
Hence, 4.33 mm is the maximum allowable deflection in the snaps.
Fb = 1.8 x (1.45)2
x 3500 x 0.15 = 49.42 N
6 x 6.7
Hence, 49.42 N is the maximum deflection force the snap can withstand without
breaking.
3.2.3 SCREW DETAILS
The dimensional details of the screw is listed in table 3.5
Table 3.5 Table indicating dimensional parameters of 1.8T screw

3.2.4 CAD DRAWINGS OF SLIDING BRIDGE CONCEPT
Figure. 3.7 shows the CAD drawing of the fixing frame for sliding bridge concept.
Fig. 3.7 CAD drawing of sliding bridge concept
TOP VIEW
SIDE VIEW
FRONT VIEW

Figure. 3.8 shows the CAD drawing of the bridge component of the sliding bridge
concept.
Fig. 3.8 CAD drawing of sliding bridge concept
FRONT VIEWSIDE VIEW
ISOMETRIC VIEW
TOP VIEW

3.3 STRUCTURAL ANALYSIS
Structural analysis of the fixing frame and the bridge is performed to find out the
stresses generated and displacements produced due to loading. The stresses and
displacements should be within the limits for the design to be safe. PRO-
MECHANICA is the FEA package used for the analysis.
3.3.1 STRUCTURAL ANALYSIS OF THE FIXING FRAME
Assumptions:
1. The material is assumed non linear isotropic.
2. 3D model.
3. Stresses developed at loading area are ignored due to St.Venants theory and
confident of design team that part will not fail at this location.
4. Pre load generating due torque on screw found by following values. If any
variations in the assumed value results will vary (pre load will vary).
Boundary conditions for the analysis of the sliding bridge model:
Material: ZAMAK 5
Young’s Modulus: 85 GPa
Poisson’s ratio: 0.27
Yield tensile stress: 269 MPa
Ultimate tensile stress: 330 MPa
 For simulation purpose the fixing frame is divided into two halves
symmetrically.
 The three screw holes positions were fixed and restricted to all degrees of
freedom.
 Box surface was fixed and restricted to all degrees of freedom.
The following figures show the simulation results of the ZAMAK fixing frame.
Fig 3.9 shows the Von Misses stress generated in the fixing frame when the frame is
fixed at the three screw positions. The maximum stress generated when a pull out
force of 22 kgf will be applied on the insert is 209 MPa (red portion), which was less
than the tensile strength of the ZAMAK material (330 MPa).

Figure 3.9 Von Misses Stress distribution in the Fixing Frame
Fig 3.10 shows the displacement variation in the fixing frame when a pull out force of
22 kgf is applied on the inserts.The max displacement was .02885 mm which is lesser
compared to the overall dimensions of the frame. (Refer Appendix III for scale
readability for all results).
Therefore, some amount of clearance or gap has to be provided between the fixing
frame and the asethetic cover frame to take care of the displacement of the fixing
frame.
Figure 3.10 Displacement in Z direction for fixing frame

Fig 3.11 and Fig 3.12 shows the strains produced in the fixing frame in ZZ and XX
directions respectively. The maximum strains produced are 0.00129 in both the
directions. These strains in both directions are well within the limits of actual use of
5%.
Figure 3.11 Strain in ZZ direction for fixing frame
Figure 3.12 Strain in XX direction for fixing frame
3.3.2 STRUCTURAL ANALYSIS OF THE BRIDGE COMPONENT
Structural analysis of the bridge was done to validate the capacity of the bridge to
withstand the pull or push force and to find the stress, strain and displacements in it.

Fig 3.13 shows the Von Misses stress generated in the bridge. The maximum stress
observed was 34.57 MPa, which was found to be lesser than the yield strength of
ZAMAK (269 MPa). Hence the bridge is capable of withstanding the maximum force
(220 Newton) applied onto it.
Figure 3.13 Von Misses Stress distribution in the bridge due to bending in bridge
component
Fig. 3.14 shows the displacement of the bridge in YY direction. The maximum
displacement experienced by bridge is 0.0162 mm which is lesser compared to the
overall dimensions of the FF. The portion in red indicates the region where maximum
displacement takes place upon loading.
Figure 3.14 Displacement of the bridge in YY direction in bridge component

Fig 3.15 and Fig 3.16 shows the strains produced in the fixing frame in ZZ and YY
directions respectively. The maximum strains produced are 0.000417 and 0.00027
respectively in ZZ and YY directions. These strains in both directions are well within
the limits of actual use of 5%.
Figure 3.15 Strain in ZZ direction for bridge component
Figure 3.16 Strain in YY direction for bridge component

3.4 TOLERANCE ANALYSIS
Tolerances, the allowance on dimensional and shape variation of a design, are
essential features of the design. As such, they should be present in the virtual
prototype world of MCAD. The checking and fine-tuning of tolerances is a
painstaking task, which has become easier with advanced dedicated software. The
newest trend is to integrate the dedicated expert software systems in the Pro-E FEA
package [15].
Features & Benefits:
 Quickly analyze a model for its true statistical variation, sigma quality, as well
as individual dimension contributions and sensitivities.
 Easily incorporate GTOL and dimensional tolerances directly in the CAD
model. 1-D tolerance loops are managed in an assembly-level saved Tolerance
Analysis.
 Improve design for manufacturability, reduce time-to-market, improve product
quality, and decrease cost.
3.4.1 NEED FOR TOLERANCE IN THE FIXING FRAME
Dimensions, properties, or conditions may vary within certain practical limits without
significantly affecting functioning of equipment or a process. Tolerances are specified
to allow reasonable leeway for imperfections and inherent variability without
compromising performance.
A variation beyond the tolerance (for example, a temperature that's too hot or too
cold) is said to be non-compliant, rejected, or exceeding the tolerance (regardless of if
this breach was of the lower or the upper bound). If the tolerance is set too restrictive,
resulting in most objects run by it being rejected, it is said to be intolerant.
3.4.2 TOLERANCE ANALYSIS USING TOLERANCE MANAGER
The tolerances are calculated in areas where there are interactions between the fixing
frame and the sliding bridge component, between the inserts and fixing frame.
Necessary tolerances are to be provided in the fixing frame for proper snapping of the

inserts to the fixing frame so that it is appropriate for easy of assembly and
disassembly. Further in the region of opening for the bridge to slide in the fixing
frame for horizontal and vertical installation necessary tolerances are to be provided
so that the bridge component slides easily and is stopped at required positions without
affecting the snapping of the inserts to the fixing frame.
Figure 3.17 Tolerance Manager [16]
Figure. 3.17 shows the snapshot of the Tolerance Manager software. The allowable
tolerance range provided for the interference of snapping of inserts to the fixing frame
is from -1.24 to -1. Negative, because it is the portion that is interfering with the
fixing frame. The overlap of the inserts with the FF is 1mm, so the range provided is
sufficient for proper snapping.

Figure 3.18 Graph to determine the Functional Condition using Tolerance Manager [16]
Figure.3.18 shows the graph which indicates that the tolerance provided for the design
of the fixing frame is well within the 6 sigma regulations. The red portion is the
allowable tolerance for the design between -1.24mm to -1mm. The blue region
indicates that nominal range of tolerance. It is called the Functional Condition. The
evenly distributed green region implies that tolerance provided is according 6 sigma
methodologies. Table 3.6 indicates the range of Functional Condition.
Table 3.6 Table indicating the range of Functional Condition
The theoretical and structural analysis results for the fixing frame were compared and
the results are discussed in the next section.

3.5 SUMMARY
Basic experimental design and analysis for product development is successfully
planned and executed by the developmental team. Important characters and features
of the available materials for production were considered and evaluated in material
selection. The design considerations and parameters of the fixing frame for safe
operations are theoretically calculated and also validated through structural analysis
results. The necessary tolerances are provided and the methodology followed for
providing tolerances is discussed.
In this chapter engineering drawings and CAD models of the design work were
detailed out. Structural analysis of the fixing frame was performed to analyze stress
distribution, strength carrying capacity keeping a failure stress at 22kgf. The
displacements in the fixing frame and the bridge upon loading were .02885 mm and
0.0162 mm respectively, keeping the allowable strain levels at 5%. The maximum
stress generated in the bridge component through analysis was about 34.57MPa and
the maximum bending stress calculated theoretically was around 45.3MPa, so the
deviation from analytical and structural analysis was around 20%. These results also
helped in validating the theoretical design calculations.
After the detailed design of the fixing frame is carried out, the next step was to go for
prototyping of the finalized design concept. The prototyping methodology adopted
and first hands-on feel of the prototypes are discussed in the next chapter.

CHAPTER-4
4.0 PROTOTYPING OF FIXING FRAMES
Product development almost always requires the building and testing of prototypes. A
prototype is an approximation of the product on one or more dimensions of interest.
The 3-D CAD modeling and free form fabrication technologies have reduced the
relative cost and time required to create and analyze prototypes. In this project, three
design concepts of the fixing frame are realized through prototyping.
The basic principle and working of prototyping machine are studied. The Fused
Deposition Modeling process which is used in this case of prototyping technique and
the highlights of FDM processes are studied. The materials used for the prototyping
processes are explained. The basic methodologies adopted for developing the
prototypes of the fixing frames are discussed. The results of the prototypes in terms of
effectiveness of its functionality are discussed.
4.1 RAPID PROTOTYPING
Rapid Prototyping (RP) enables the quick fabrication of physical models using three-
dimensional computer aided design (CAD) data. Used in a wide range of industries,
Rapid prototyping allows companies to turn innovative ideas into successful end
products rapidly and efficiently.
Rapid prototyping techniques offer multiple benefits, such as:
 Fast and effective communication of design ideas
 Effective validation of design fit, form, and function
 Greater design flexibility, with the ability to run quickly through multiple
design iterations
 Fewer production design flaws and better end-products.
4.1.1 WORKING OF RAPID PROTOTYPING MACHINE
Rapid Prototyping, also known as 3D printing, is an additive manufacturing
technology. The process begins with taking a virtual design from modeling or
computer aided design (CAD) software. The 3D printing machine reads the data from

the CAD drawing and lays down successive layers of liquid, powder, or sheet material
— building up the physical model from a series of cross sections. These layers, which
correspond to the virtual cross section from the CAD model, are automatically joined
together to create the final shape. To obtain the necessary motion control trajectories
to drive the actual SFF, Rapid Prototyping, 3D Printing or Additive Manufacturing
mechanism, the prepared geometric model is typically sliced into layers, and the slices
are scanned into lines in reverse the layer-to-layer physical building process.[2]
Rapid Prototyping uses a standard data interface, implemented as the STL file format,
to translate from the CAD software to the 3D prototyping machine. The STL file
approximates the shape of a part or assembly using triangular facets. Typically, Rapid
Prototyping systems can produce 3D models within a few hours. Yet, this can vary
widely, depending on the type of machine being used and the size and number of
models being produced.
The Dimension Elite 3D Printer as shown in the Fig 4.1 features the finest resolution
of any Stratasys Design Series Performance 3D Printer. Driven by Fused Deposition
Modeling (FDM) Technology, it prints in nine colors of real ABSplus thermoplastic.
For times there is no need for the finest Dimension resolution of .178 mm (0.007 in.),
this 3D printer lets speeding up printing with a layer thicknesses of 0.254 mm (0.010
in.) [10].
Figure 4.1 Rapid prototyping machine setup

4.1.2 MATERIALS AND BASES
As the growing number of new applications constantly motivate in developing new
materials, it is essential to study the feasibility of new materials suitable for layered
manufacturing. The properties of the material, particle size, fusibility of powder
particles and thermal and optical characteristics are the bottlenecks in achieving
required mechanical properties, feature resolution, accuracy and surface quality of the
end product.
Dimension 3D printers use ABSplus thermoplastic to build models. Model and
soluble support materials come in convenient enclosed cartridges that are a snap to
load. Inside the 3D printer, plastic filament travels through a tube to the print head,
where it’s heated to a semi-liquid state and extruded in thin, accurate layers. ABSplus
is a true production-grade thermoplastic that is durable enough to perform virtually
the same as production parts.
When combined with Dimension 3D Printers, ABSplus is the ideal solution to
printing 3D models in an office environment. Along with ABS, some FDM machines
also print in other thermoplastics, like polycarbonate (PC) or polyetherimide (PEI).
Support materials are usually water-soluble wax or brittle thermoplastics, like
polyphenylsulfone (PPSF).
Modeling bases provide a stable platform where prototype builds. Once printing is
done, simply take the recyclable plastic base out of your 3D printer and snap off the
model [10].
4.2 FUSED DEPOSITION MODELING
Stratasys of Eden Prairie, MN makes Fused Deposition Modeling (FDM) machines.
The FDM process was developed by Scott Crump in 1988. The fundamental process
involves heating a filament of thermoplastic polymer and squeezing it out like
toothpaste from a tube to form the RP layers as shown in the Fig 4.2. The machines
range from fast concept modelers to slower, high-precision machines. The materials
include polyester, ABS, elastomers, and investment casting wax [10].

The overall arrangement is illustrated below:
Figure 4.2 Fused deposition modeling process
4.2.1 HIGHLIGHTS OF FUSED DEPOSITION MODELING
 Standard engineering thermoplastics, such as ABS, can be used to produce
structurally functional models.
 Two build materials can be used, and latticework interiors are an option.
 Parts up to 600 × 600 × 500 mm (24 × 24 × 20 inches) can be produced.
 Filament of heated thermoplastic polymer is squeezed out like toothpaste from
a tube.
 Thermoplastic is cooled rapidly since the platform is maintained at a lower
temperature.
 Milling step not included and layer deposition is sometimes non-uniform so
"plane" can become skewed.
 Not as prevalent as SLA and SLS®
, but gaining ground because of the
desirable material properties.

4.3 RAPID PROTOTYPING OF FIXING FRAME
4.3.1 METHODOLOGY OF RAPID PROTOTYPING FOR FIXING FRAMES
The basic methodology for all current rapid prototyping techniques can be
summarized as follows:
1. A CAD model of the fixing frame is constructed, and then converted to STL
format. The resolution can be set to minimize stair stepping.
2. The RP machine processes the .STL file of the fixing frame by creating sliced
layers of the model.
3. The first layer of the physical model is created. The fixing frame model is then
lowered by the thickness of the next layer, and the process is repeated until
completion of the model.
4. The fixing frame model and any supports are removed. The surface of the
model is then finished and cleaned.
4.3.2 PROTOTYPES OF FIXING FRAME
The prototypes of all the three concepts were obtained following the above mentioned
methodology as shown in the Fig 4.3. All the prototype models were working fine and
were tested for fit and tolerance tests. The prototyping of all the concepts were fed
into the machine in two batches. The time of prototyping was approximately 4 hours
for each batch. The removal of base material and cleaning of the prototypes took
another one hour for each batch. Totally two full working days were taken from the
time of feeding the models into the machine till the time the finished prototypes were
experienced hands-on.
Out of all the prototypes of the fixing frame, the prototype for the sliding bridge
concept gave the best results in terms of assembly and disassembly, tolerance and
functionality. The sliding bridge concept fixing frame was revised twice before
arriving at the finalized design. The time of assembly and disassembly was calculated
for the sliding bridge fixing frame along with installation box, inserts and aesthetic

cover frame keeping in mind the ergonomics of the design. The results for installation
time were very satisfying and better than the existing fixing frames.
4.3 Prototypes of the fixing frame concepts
4.4 SUMMARY
The rapid prototyping technique using Fused Deposition Modeling process was
discussed in depth. The results of the prototypes very found to be very satisfying.
Various scenarios, possible combinations and arrangements of the prototypes with the
available enclosure components are discussed in the next chapter. The standardization
methods, effects and the influences of using the sliding bridge are discussed in the
next chapter.

CHAPTER-5
5.0 RESULTS AND DISCUSSIONS ON FIXING
FRAMES
The objective and purpose of this design work was to have a universal and standard
solution for the design of the fixing frames which could offer a unique solution for
horizontal and vertical installation practices. At this stage, having a design concept
which satisfies the objective of the project, it is necessary to provide acceptable and
conclusive evidences of the fixing frame design which proves the credibility and the
effectiveness of the design work. The effects and influence of the bridge component
in the fixing frame which satisfies the needs and requirements have been thoroughly
discussed.
5.1 STANDARDIZATION OF FIXING FRAMES FOR
HORIZONTAL AND VERTICAL INSTALLATION
The fixing frame has been designed which offers best solution in terms of its mode of
operation and functionality. Here the “Sliding Bridge” design concept has many
advantages over other design concepts which were earlier described. This design in
fact proves to be more efficient and effective than the solution proposed by “Legrand”
for the same problem statement. The sliding bridge is still effectively a part integrated
to the fixing frame. It can as well be removed and scrapped as per the requirements
and use, and the ways of arrangement of the wiring devices to the fixing frame. It
provides that extra edge and sense of flexibility to the use. The number of wiring
devices going in to the wall snapped to the fixing frame ultimately decides the use and
state of the sliding bridge of the fixing frame.
When the need arises where the wiring devices needs to be arranged horizontally, the
very purpose of having a standard and universal fixing frame is to reduce the burden
on the shoulders of the end users and having them to still effectively use the same
fixing frame and other set of enclosure components in a way that they still end up
arranging the same product from horizontal to vertical installation and vice-versa as

per the requirements and needs. There is finally no need for the end users to invest on
the wiring devices except for some changes in the wall structure and composition.
Ultimately, this design concept requires no change in the design of the enclosure
components. Meaning to say that every other enclosure component like switches,
sockets, regulators, adapters, etc, installation box and aesthetic cover frame will still
retain its existing design originality. There is absolutely no refinement in the design of
the other enclosure components and in the way these are assembled to each other. The
functionality of the earlier fixing frame is still carried to this fixing frame and is
restored. The whole set of the “Modularity” is still being restored. This adds to the
compactness and also to the simplicity of the design with absolutely no investment on
other parts of the enclosure components except for the fixing frame to achieve the
required objective.
5.1.1 STANDARD METHODS
Horizontal installation: The sliding bridge is rested at the ends of the window
opening provided for snapping of the inserts. The installation box is first installed to
the wall, and then the fixing frame is either clawed or screwed to the box. Then the
inserts are snapped horizontally to the fixing frame. Then the aesthetic cover frame is
snapped to the fixing frame to complete the assembly. If the need arises as to have
71mm pitch between the inserts then the sliding bridge is moved and rested to the
position and location where the sliding portion ends. This end position of the sliding
window is effectively the position for snapping of inserts to the fixing frame as a
71mm pitch arrangement as shown in the Fig 5.1.
Figure 5.1 Horizontal installation practice of FF

Vertical installation: The orientation of the entire assembly of the product changes
from horizontal to vertical installation to the wall as shown in the Fig 5.2. Keeping the
functionality of the wiring devices and their mode of operations still the same from
horizontal i.e., the switch or a socket needs to be used and operated in a normal
practiced way. So now the sliding bridge is moved to positions to the ends of the
siding window. This position of the sliding bridge provides snapping support to the
inserts between the bridge itself and one end of the fixing frame. The assembly
procedure is followed same for vertical installation as in horizontal.
Figure 5.2 Vertical installation practice of FF
5.1.2 STANDARDS ACHIEVED
Standard 1 achieved: Having a single fixing frame for both types of installation
practices makes it universal and a standard to use.

Standard 2 achieved: The evidences show that the inserts are snapped on to the same
fixing frame both horizontally and vertically. Here the standard is by using the same
fixing frame the continuous arrangements for 57mm pitch and 71mm pitches for
horizontal installation with the use of the bridge at required location was achieved.
Standard 3 achieved: The location and positioning of the sliding bridge at the ends
of sliding window for vertical installation and snapping of inserts matches the
positioning and location of the inserts for the continuous horizontal arrangement for
71mm pitch.
5.2 EFFECT OF USING THE SLIDING BRIDGE COMPONENT
IN THE FIXING FRAME
5.2.1 SCENARIO 1: Horizontal continuous 8 modules/4 gang-57mm pitch
without bridge
Here in this scenario as shown in the Fig 5.3, using the fixing frame without the
sliding bridge makes it possible to arrange 8 modules (22.5x44.5) and 4 gangs
(44.5x44.5) horizontally in continuous arrangement. Without making use of the
bridge here in this scenario allows the installer to add one or two more inserts to the
fixing frame than with the sliding bridge.
Figure 5.3 Horizontal continuous 8 modules/4 gang-57mm pitch without bridge
5.2.2 SCENARIO 2: Horizontal continuous 6 modules/3 gang-57mm pitch with
bridge
In this scenario as shown in the Fig 5.4 the sliding bridge is made use of and
integrated it to the fixing frame. The sliding bridge is positioned at the ends of the

window for inserts at both ends of the fixing frame. This set up allows 6 modules or 3
gangs to go into the fixing frame.
Figure 5.4 Horizontal continuous 6 modules/3 gang-57mm pitch with bridge
5.2.3 SCENARIO 3: Horizontal continuous 6 modules/3 gang-71mm pitch with
bridge
In this scenario as shown in the Fig 5.5 the bridge is positioned at the ends of the
sliding window provided for vertical installation. This position of the sliding bridge
makes it possible for installer to have 6 modules or 3 gangs of inserts arranged for
71mm pitch.
Figure 5.5 Horizontal continuous 6 modules/3 gang-71mm pitch with bridge
5.2.4 SCENARIO 4: Vertical continuous 6 modules/3 gang-71mm pitch with
bridge
This is the most important arrangement scenarios’ for the design of the fixing frame is
as shown in the Fig 5.6. Here the sliding bridge is positioned and located at ends of
the sliding window in the fixing frame. The distance between one end of the fixing
frame and the bridge and also the distance between the bridges allows 6 modules or 3
gangs to be perfectly snapped to the fixing frame vertically.

Figure 5.6 Vertical continuous 6 modules/3 gang-71mm pitch with bridge
Here all possible standard installation scenarios were discussed which are currently in
use in the market. So this fixing frame is a multipurpose one which offers solution to
have possible variety of installation practices both horizontally and vertically.
This major outcome of this design concept of the fixing frame is that it brings about
a process change and a product change in terms of installation habit, installation
time and cost, and number of parts in the architecture. This fixing frame replaces
three single gang FFs by a single FF which again offers the same solution saving huge
amount time and money in the long run.

5.3 INFLUENCE OF USING THE SLIDING BRIDGE IN THE
FIXING FRAME
5.3.1 INFLUENCE ON THE STRENGTH
The strength of the fixing frame is one of the most important criteria in designing the
fixing frame as shown in the Fig 5.8. Making it possible and having the sliding bridge
to achieve our objective slightly affects the strength of the fixing. The portion of the
fixing frame where the window opening is provided for sliding the bridge makes the
fixing frame more vulnerable and susceptible to warping and periodic deflection.
The gap provided for sliding bridge reduces surface area for contact between the
lower portion and upper portion of the fixing frame as shown in the Fig 5.7. There is
possibility that overall strength carrying capacity of the fixing frame reduces when the
pull out tests and push tests for socket outlets and switches are performed. Due to the
large opening provided on the sides of the fixing frame the stress concentration in the
fixing frame increases.
Figure 5.7 Window opening
for sliding bridge which is
the site for stress
concentration and strength
reduction.
Figure 5.8 Existing fixing
frame design without
opening on the sides, so
the component is uniform
with no strength
reduction.

5.3.2 INFLUENCE ON THE DIRECTORS THAT RESTRICT THE
HORIZONTAL MOVEMENT OF INSERTS
The directors on the inner surface of the window opening for inserts in the design of
existing fixing frame were provided to restrict horizontal movement of the inserts as
shown in the Fig 5.9. The degree of freedom in horizontal direction was locked and
the location of the insert in the fixing frame was restricted to a specified position once
the inserts were snapped to the fixing frame.
Once the window opening was provided for the sliding bridge, a large number of
directors were removed which were located in the space that has been cut out for the
window opening as shown in the Fig 5.10. So to have uniformity in the design, all
such directors were completely removed from the fixing frame. So in the new design,
the entire fixing frame is plain and without directors guiding the inserts for specified
position of snapping.
The advantage of not having directors in the fixing frame is that the inserts are free to
be moved and placed at required position in the fixing frame as per the needs and
requirements. This reduces the burden on the end users to disassemble the insert from
the fixing frame and to assemble it again to a required position. This design
refinement adds to the ease of assembly and disassembly in the fixing frame. Here
again one more part (which is large in number on the fixing frame) is reduced to be
designed and to be molded into the fixing frame. This reduces the cost of
manufacturing and also saves the material for manufacturing. This small design
refinement saves a lot of money when it comes to production of the fixing frame
components in large numbers.
Figure 5.9 Existing fixing
frame with director
components to restrict
horizontal movement of
inserts.

REPORT FINAL

Recommended

Recommended

More Related Content

Similar to REPORT FINAL

Similar to REPORT FINAL (20)

REPORT FINAL