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Application of Design for Manufacturing and Assembly (DFMA) Methodology in
the Steel Furniture Industry
Conference Paper · March 2016
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2. National Conference on Technological Advancements in Engineering -2016
Sree Narayana Guru College of Engineering and Technology, Payyanur
March 2016
1
Abstract
Design for manufacturing and assembly is widely used by
product designers and engineers to design products with
lesser number of parts which helps in ease of assembly and
thereby reducing the overall cost. This paper gives an
overview on Design for Manufacture and assembly, an
application that can be used throughout various industries
to reduce the overall costing of a product, hence helping to
improve the overall company productivity. Two case studies
with respect to DFMA usage and its advantages are
presented in the current study. The products are analyzed
for DFMA and redesigned for cost reduction.
1. Introduction
DFMA is developed to give engineers a method to
evaluate assembly and the manufacturability of a product
and an aid to product development. Today companies
worldwide are battling to reduce the cost of the products in
order to increase profitability. Cost cutting of a product
begins at the design stage. This is where DFMA takes its
role. DFMA consists of a two part analysis of a product,
Design for Assembly (DFA) and Design for Manufacturing
(DFM) (Boothroyd, 1994).
DFMA presents a methodology for product structure
simplification through an integration ofthe DFMA software
with the Theory of Invention Problem Solving (Lucchetta
et.al, 2005). Cost data is rarely available for the designer in
the usable form. DFMA software can be used to investigate
the possibilities of activity based costing, modelling,
purchasing and manufacturing processes in providing useful
costing information to the designers (Katja.T et.al, 2002). A
complete DFMA analysis helps to give a categorical
approach to the cost to be infused with each division within
a firm to help use all resources to the most optimized
capabilities which in the end help provide more efficient
product to the consumers (Mark Oakley, 1982). DFMA can
be utilized extensively in a core field industry with
successful implementation of the software to help restrain
the costing capabilities of a firm (Xiaofan Xie, 2006). In
this paper two case studies: one being DFMA of folding
chair and the other the DFMA of bunk bed is discussed.
1.1. Traditional design approach
Generally projects start off with certain problems which
are caused by misinterpretation of the available data, low
precision rate, lack of complete information etc., and which
could extend towards the entirety of the project unless the
mistakes are nipped at the bud.
Imprecise communication between the involved parts
could also be a problem the project may face and hence
must be categorized with other limitations such as machine
restrictions, low investments, schedules, space and logistics.
Hence we come across the necessity to create a new product
with cost effective measures taken into account within the
shortest possible times, all without losing the knowledge
acquired about the processes and also our consumer
requirements. A traditional design project generally has
certain steps to be followed mainly being; - Identification of
customer needs and desires as an input, - An output
represented by the product or service to match the
consumer’s needs to the fullest possible extent.
DFMA helps optimize both of these important methods
into one single step wherein it takes into consideration the
needs and desires of the consumer and also optimizes the
correct design to be chosen which will help reduce overall
production cost and hence help improve entire productivity.
It also helps reduce the usage of a lot of redundant parts or
assemblies in a product.
The traditional design, fails to interpret certain
information that flows from the input process to the output
process, information that can show certain limitations
and/or show certain situations that abet or rather call for
certain changes or improvements in the entire procedures
used. All these limitations and erogenous interpretations
call for the use of an efficient process, such as, the DFMA.
The design of a product determines its manufacturability,
not the manufacturer itself, whatever levels ofsophistication
are taken into account. DFMA helps us sort out and
categorize the entire list of products and parts required for a
design and also helps us make the decision of which
redundant part or parts can be omitted from the project in
order to reduce the overall cost of the project.
Application of Design for Manufacturing and Assembly (DFMA)
Methodology in the Steel Furniture Industry
C D Naiju, Jayakrishnan V, Pranav V. Warrier and Rijul B
School of Mechanical Engineering
VIT University
cdnaiju@vit.ac.in
3. National Conference on Technological Advancements in Engineering -2016
Sree Narayana Guru College of Engineering and Technology, Payyanur
March 2016
2
1.2. DFMA- an overview
Organizations tend to believe in a continual learning
process because they keep trying to learn newer methods
and procedures that may help them reduce the overall
expense expended by the company in order to achieve the
same result, hence ensuring a higher productivityand alsoa
step closer to the six sigma achievement regulations
followed by a firm. The premise being, organizations learn
in order to improve their adaptability and efficiency during
times of change.
The main advantage DFMA offers is that it permits us to
run activities simultaneously in a parallel form, in
opposition of the tasks sequencing. They also allow the
usage of simulation techniques and a full synergy between
the teams i.e. the design team, manufacturing team, sales
team, finance team etc. This makes it possible to find
project failures or deviations and hence help in making the
changes required before the development procedures end.
DFMA Software is developed by Boothroyd Inc., for
optimization and is one of the most important software used
by a designer which helps during the design stage. The
various experiences a designer goes through are the result of
several mistaken situations, misinterpreted acts,
improvement opportunities or just really good ideas
acquired during the ongoing development and research in
the design area. High manufacturability level of a product
can be acquired with the help of DFMA software. Using the
techniques of DFMA, it is possible to attend to the various
issues that occur in the production and assembly line. The
most significant advantage of DFMA is the integration of
teamwork between the project, product, design,
manufacturing teams improving the designs, reliabilityand
also the improving the productivity of the product
simultaneously. The discussions above can be validated with
the help of two case studies: one being DFMA of folding
chair and the other the DFMA of bunk bed.
2. Case study 1: DFMA of folding chair
2.1. Analysis of the Existing Design
A folding chair is a portable chair that can be folded flat,
stored in a rack, row or on a cart. These chairs are used for
seating in areas where permanent seating is not practical.
They can be used in various indoor and outdoor function
like weddings, funerals etc. The CAD model is shown in the
fig 1 below. The existing design of the folding chair consists
of three round frames and a seat, which are all fastened with
the parts respect to each other. This frame consists ofa solid
round frames which are much thicker when compared tothe
re-designed model, making the frame heavier, hence more
expensive. The costing of the existing model of the folding
chair for a batch size of 1,000 products is given in table1.
Fig 1. Existing design of the folding chair
Table 1 Costing details before DFMA
No. Part Process Material
Cost
(Rs.)
1 Frame 1
Cutting/Weldin
g
Mild
Steel
150
2 Frame 2
Cutting/Weldin
g
Mild
Steel
75
3 Seat
Stamping/
Welding
Mild
Steel
450
2.2. Re-Design of folding chair
The re-designed model of the folding chair was carried
out considering the ease of assembly and reduction in
material and manufacturing process. The model consists of
a void at the top of the seat which reduces the use of
redundant parts, to the side of the frame are present two
hinges which are usually not taken into account when
conducting a DFMA analysis on the product.
Fig 2. Re-designed model
4. National Conference on Technological Advancements in Engineering -2016
Sree Narayana Guru College of Engineering and Technology, Payyanur
March 2016
3
The changes made were, them being Frame1, Frame 2
and seat. The new re-designed CAD model is shown in fig 2
below. The re-designed design of the chair consists of two
solid frames and a seat which are all spot welded with each
other hence helping to reduce the overall number of parts of
the chair from 9 to 3, also aimed at improving the
productivity. The costing detail for the new re-designed
model is shown in table 2.
Table 2. Costing details after DFMA
SL
No.
Part Process Material
Cost
(Rs.)
1 Frame 1
Cutting/
Welding
Mild Steel 135
2 Frame 2
Cutting/
Welding
Mild Steel 67
3 Seat
Stamping/
Welding
Mild Steel 405
3. Case Study 2: Bunk bed
3.1. Analysis of DFM for existing model
A bunk bed is a type of bed in which one or more cots can
be stacked one above the other helping us to utilize the
amount of space available to us in the best possible manner.
A bunk bed ensures that two or more people can occupy the
same amount of space required by a single person on a
single cot in a room. The existing design of the bunk bed
CAD model in shown in fig 3. Costing details for a batch
size if 1,000 before DFMA is shown in table 3. The figure
of the existing bunker bed is shown in figure 3, and its
costing model is provided in table number 3. The existing
model of the bunker bed consists of 12 different frames and
two bed plates which are fastened with each other.
Fig 3. Existing Model
Table 3. Costing details before DFMA
No. Part Process Material
Cost
(Rs.)
1 Base Stamping
Mild
Steel
153
2
Side
Support1
Cutting/
Welding
Mild
Steel
760
3
Side
Support3
Cutting/
Welding
Mild
Steel
1300
4 Bed
Cutting/
Welding
Mild
Steel
1900
5
Square
Bucket
Cutting/
Welding
Mild
Steel
300
6
Side top
Support
Assembly
fabrication
Mild
Steel
500
7 Bolt
Assembly
fabrication
Mild
Steel
0
8 Nut
Assembly
fabrication
Mild
Steel
0
3.2 Redesign of bunk bed
The redesigned model of the bunker bed now consists
of 7 different frames and two bed plates which are arc
welded with some parts and the rest of the parts being
fastened.
Fig 4. Re-designed Model
The figure of the re-designed bed can be seen in figure 4
and its costing model is provided in table number 4.The
wall mount tends to reduce the moving ability of the bed,
5. National Conference on Technological Advancements in Engineering -2016
Sree Narayana Guru College of Engineering and Technology, Payyanur
March 2016
4
nut helps reduce the number of parts to a considerable
extent enabling them to create a similar functioning product
for a smaller price range. Two projections can be seen on
the other side of the re designed bed which enables it to be
wall mounted and hence proves the part that a bunker bed
can be manufactured with lesser number of parts.
Table 4. Costing Details post DFMA
No. Part Process Material
Cost
(Rs.)
1 Base Stamping
Mild
Steel
148
2 Support
Cutting/
Welding
Mild
Steel
750
3 Bed
Cutting/
Welding
Mild
Steel
1200
4 Step
Cutting/
Welding
Mild
Steel
1500
5 Bolt
Assembly
fabrication
Mild
Steel
0
6 Nut
Assembly
fabrication
Mild
Steel
0
4. Conclusion
Design for manufacture and assemblywas conducted on a
bunker bed and a more optimized design was created which
helped improve the productivity of the product with respect
to costing. Form the case studies it was analyzed that for a
folding chair the total number parts of the chair were
reduced from 9 to 3, with the help of DFMA software. The
design was modified for ease in assembly. There was a
reduction in time for assembly of the product, as well. By
selection of proper materials and manufacturing processes
along with optimized assembly helped reduce the overall
cost of the folding chair from Rs. 675 per product toRs. 607
for a life volume of 10 units. When conducted on a bunker
bed the total weight of the product was reduced from 867.13
lb to 385.08 lb. Total number of parts of the new product
was reduced from 29 to 9, and its total cost has reduced
from Rs. 4530 to Rs. 3630.
References
[1] M Dekker, G. Boothroyd, P. Dewhurst, and W. Knight,
Product Design for Manufacturing and Assembly”, New
York, Dewhurst, P., Boothroyd, G. (2003) ‘Early Cost
Estimation In Product Design’, Journal of Manufacturing
Systems, 7:.183-192, 1994.
[2] G. Lucchetta, P. F. Bariani and W. A. Knight- Integrated
Design Analysis for product simplifications. CIRP Annals-
Manufacturing Technology, 54(1):147-150, 2009.
[3] T. Katja, J. Miikka and P. Jari-Activity-based costing and
process modelling for cost-conscious product design: A case
study in a manufacturing company. International Journal
Production Economics, 79(1):75-8, 2002.
[4] M. Oakley-Product design and development in small firms.
Operations Management Group, 3(1): 5-9, 1982.
[5] X. Xie- Design for manufacture and assembly. Applied
Mechanics and Machines, 313-314(1): 11-14, 2006.
[6] J. P. B. Kovalchuk-DFMA Application on the development of
parts for the white goods industry. Third International
Conference on Production Research, 2006.
[7] K. Annamalai, C. D. Naiju, S. Karthik, M. M. Prashanth-
Early Cost Estimate of Product during Design Stage Using
Design for Manufacturing and Assembly (DFMA) Principles.
Advanced Materials Research, 622-623(1):540-544.
[8] S. Ejaz, MG Arjun, CD Naiju, K Annamalai,
Conceptualization Design for Manufacture and Assembly
(DFMA) of Juicer Mixer Grinder, National Conference on
Advances in Mechanical Engineering, NCAME-2011, India,
March-23-24, 297-302, 2001.
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