This document discusses various assembly methods including manual, automated, and robotic assembly. It provides details on the characteristics, guidelines, types, and factors for selecting each assembly method. Manual assembly relies on human workers and is flexible but has a constant cost. Automated assembly uses machines and is best for high volumes but requires more capital. Robotic assembly falls between manual and automated in terms of volume and capital needs. The document provides pros and cons and considerations for each assembly method.

1. DESIGN OF ASSEMBLY
METHODS
Guided By:
Prof. D.K Patel
Presented By:
Aman Kumar Parshad
160280708001
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2. TABLEOFCONTENTS
OBJECTIVE OF DESIGN
FOR ASSEMBLY
TYPES OF ASSEMBLY
METHODS
MANUAL ASSEMBLY
AUTOMATED ASSEMBLY
ROBOTIC ASSEMBLY
REFERENCES
SELECTION OF
ASSEMBLY METHODS
COMPARISON OF
ASSEMBLY METHODS
1
2
3
4
5
6
7
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“The aim of DESIGN FOR ASSEMBLY
(DFA) is to simplify the product so
that the cost of assembly is reduced.”
[1]
Further,
 It also improved quality and reliability and,
 It helps in reduction in production equipment and
part inventory.
OBJECTIVES OF DESIGN FOR ASSEMBLY (DFA)

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1. Manual assembly
2. Automatic assembly
3. Robotic assembly
TYPES OF ASSEMBLY METHOD

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2. Manual Assembly

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 A Manual assembly line is a production line that consists of a sequence of workstations.
 At each workstation Product are assembled by human workers as they move along the line.
 At each station, a portion of the total work is performed on each unit.
 The common practice is to "launch" base parts onto the beginning of the line at regular
intervals.
WHAT IS MANUAL ASSEMBLY ? [3]

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 Each base part travels through successive stations and workers add components that
progressively build the product.
 A mechanized material transport system is typically used to move the base part along the
line as it is gradually transformed into the final product.
 The production rate of an assembly line is determined by its slowest station.

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 In manual assembly, the operations are carried out manually with or without the aid of
simple, general purpose tools like screwdrivers and pliers.
 Individual components are transferred to the workbench either manually or by employing
mechanical equipment such as parts feeds or transfer lines and then are manually
assembled.
 Bins with typically un-oriented parts. Simple clamping fixtures.
 This assembly method is characterized by its flexibility and adaptability.
 The assembly cost per product is nearly constant.
 Cost is not a function of volume. Instead, function of labour rate.
 Good for low to high volume. Very low capital investment
CHARACTERISTICS OF ASSEMBLY METHODS [1]

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• Eliminate the need for workers to make decisions or adjustments
• Ensure accessibility and visibility
• Eliminate the need for assembly tools and gauges (self-locating parts)
• Minimize the number of different parts - use "standard" parts
• Minimize the number of parts
• Avoid or minimize part orientation during assembly (symmetrical parts)
• Prefer easily handled parts that do not tangle or nest within one another
Many such products are sold as "ready-to-assemble" kits or
require that assembly be shifted to cheaper labor markets.
DESIGN GUIDELINES FOR MANUAL ASSEMBLY [1]

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• The process of manual assembly can be divided into two
separate areas:
1. Handling (acquiring, orienting, and moving the parts)
2. Insertion and Fastening (mating a part to another part
or group of parts)
GENERAL DESIGN GUIDELINES FOR MANUALASSEMBLY [1]

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a) Parts must have end-to-end symmetry and rotational
symmetry about the axis of insertion.
b) Part cannot be made symmetric, are obviously asymmetric.
c) Provide features that will prevent jamming of parts that tend
to nest or stack when stored in bulk
d) Parts which can tend to nest or stack when stored in bulk,
e) Parts must be tangled free
f) Avoid parts that are sharp and splinter easily.
(f)
PART HANDLING

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1. Design so that there is little or no resistance to insertion and provide chamfers to guide
insertion of two mating parts.
FOR INSERTION AND FASTENING

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2. Standardize of Parts, Processes and Methods across all models.
3. Use pyramid assembly
4. Avoid the necessity for holding parts down to maintain their
5. orientation during manipulation of the subassembly.
6. Design so that a part is located before it is released.
7. Cost of different fastening processes
.
(c)(b)
(a)
Cont.…..

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(d)
(e)
i. a. Snap fitting
ii. b. Plastic bending
iii. c. Riveting
iv. d. Screw fastening
Cont…

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1. Avoid connections 2. Avoid adjustments
A
B
A A A
B
B B
FURTHER DESIGN GUIDELINES

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3. Design so that access for assembly operations is not restricted
Restricted access for assembly of screws

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1. For small parts placed within easy reach of assembly
worker, handling times given in Fig. are adequate if
employing:
 bench assembly
 multi-station assembly
2. For Large Part, It will not be possible to place an
adequate supply of parts within easy arm's reach of
assembly worker for volumes that:
 Do not justify transfer systems
 Assembly contains several parts that weigh more
than 5 lb or are over 12” in size.
 Largest part is less than 35” in size
 No part weighs more than 30 lb
 In this case, modular assembly center might be used.
TYPES OF MANUALASSEMBLY METHODS [2]

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 Application of Adhesive
 Application of Sealants
 Arc Welding
 Brazing
 Insertion of Component
 Press Fitting
 Riveting
 Soldering
 Spot Welding, etc.
Assembly Processes in Manual Assembly

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2. Automatic assembly

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Fixed automation usually:- Most automated
assembly systems are designed to perform a fixed
sequence of assembly steps on a specific product that is
produced in very large quantities.
Where is automated assembly appropriate:
 High product demand
 Stable product design
 The assembly consists of no more than a limited
number of components
 The product is designed for automated assembly
AUTOMATED ASSEMBLY[2]
“The use of mechanized and
automated devices to
perform the various
assembly tasks in an
assembly line or cell”

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 Mainly referred to as fixed automation or the Detroit type.
 Either synchronous indexing machines and automatic feeders or non-synchronous
machines where parts are handled by a free-transfer device are used.
 Machines are dedicated for the production/assembly of a product.
 These systems lack any flexibility to accommodate tangible changes in the design of
the product.
 Requires a large-scale capital investment, as well as considerable time and
engineering work before actual production can be started.
CHARACTERISTICS OF AUTOMATED ASSEMBLY METHODS

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Use self-aligning and self-locating features.
Avoid screws/bolts.
Use the largest and most rigid part as the assembly base and fixture.
Perform assembly in a layered, bottom-up manner.
Use standard components and materials.
Avoid tangling or nesting parts.
Avoid flexible and fragile parts.
Avoid parts that require orientation.
Use parts that can be fed automatically.
Design parts with a low center of gravity.
AUTOMATED ASSEMBLY GUIDELINES (HARD AUTOMATION ) [1][3]

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 Adhesive bonding Snap fitting
 Insertion of components Soldering
 Placement of components Spot welding
 Riveting Stapling
 Screw fastening Stitching
Typical Products
 Alarm clocks Light bulbs
 Ball bearings Locks
 Ball point pens Mechanical pencils
 Cigarette lighters PCB assemblies
 Door mechanisms Small electric motors
 Gear boxes Wrist watches
Assembly Processes in Automated Assembly
Blade is released by pulling back the bearing

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Based on physical configuration:
1. In-line assembly machine
2. Dial indexing machine
3. Carousel assembly system
4. Single-station assembly cell
TYPES OF AUTOMATED ASSEMBLY SYSTEMS[3]

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“A series of automatic workstations located along and inline transfer system”
Either synchronous or asynchronous work transfer used.
In-Line Assembly Machine

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Example

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 Base parts are loaded onto
fixtures or nests attached to a
circular dial table, and
components are added at
workstations located around
the periphery of the dial as it
indexes from station to
station
Dial Indexing Machine

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Example
http://www.sankyoautomation.com/applications/rotate_applications

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Dial indexing assembly machine

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“A hybrid between circular work flow of dial indexing machine and straight work
flow of in-line system”
Carousel Assembly System

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“Assembly operations are performed on a base part at a single location”
 A robot is sometimes used as the assembly machine.
Single-Station Assembly Cell

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Typical parts delivery system at a workstation
consists of the following hardware
components:
1. Hopper - container for parts
2. Parts feeder - removes parts from hopper
3. Selector and/or orientor - to assure part is in
proper orientation for assembly at workhead
4. Feed track - moves parts to assembly
workhead
5. Escapement and placement device –
removes parts from feed track and places them
at station
Parts Delivery at Workstations

35. 35http://www.nuigalway.ie/staff-sites/david_osullivan/documents/unit_14_automated_assembly_systems.pdf

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Multi-station assembly machine or line
 Faster cycle rate
 High production quantities
 More operations possible
 More components per assembly
Single-station assembly cell
 Suited to robotic assembly
 Intended for lower production quantities
Multi-Station vs. Single-Station

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3. Robotic Assembly
https://grabcad.com/library/robotic-arm-motion-1

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Production volume is higher than that of a manual assembly
system but lower than that of an automatic assembly system
(Fixed automation).
Common forms of Robotic Assembly:
1. One-arm robot operating at a single
workstation that includes parts feeders,
magazines, etc.
CHARACTERISTICS OF ASSEMBLY METHODS [3]
new.math.uiuc.edu

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2. Two robotic arms operating at a single workstation
A programmable controller (PLC) is used to simultaneously control and synchronize the
motions of the two arms. Referred as a robotic assembly cell and similar to FMS cell.

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3. Multi-station robotic assembly system
 Capable of performing several assembly operations simultaneously.
 Can perform different assembly operations at each station.
 High flexibility and adaptability to design changes.

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The product design rules for robotic assembly are basically the same as those for manual and/or automatic
assembly.
Two very important and crucial considerations
that have to be taken into account when
designing components for robotic assembly:
1. Design a component so that it can be grasped,
oriented, and inserted by that robot's end
effector. Failure to do so will result in the need
for an additional robot and, consequently,
higher assembly cost.
DESIGN FOR ROBOTIC ASSEMBLY [3]

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End-effector
2. Design parts so that they can be presented to the robot's arm in an orientation
appropriate for grasping. Also, eliminate the need for reorienting assemblies (or
subassemblies) during the assembly operation.
Cont..

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DISCRIPTION OF ROBOT
https://www.tes.com/lessons/-pQNFLLpECBSEA/robotic-arm

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Factors affecting selection of an assembly method:
 Cost of assembly
 Annual production volume (or production
rate)
 Number of individual components to be
assembled in a product
 Number of different versions of a product / s
 Availability of labour (with cost
consideration)
 Payback period
SELECTION OF ASSEMBLY METHOD [1][4]

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1. Manual assembly requires the least capital
investment followed by the two simplest forms
of robotic assembly.
2. Multi-station robotic assembly system
compares to Automatic system with special-
purpose machines requires more capital
investment for a large production volume but
less capital investment for a moderate
production volume.
3. Assembly cost per product is constant for
manual assembly
Comparison of Assembly Methods [1][4]

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4. Assembly cost per product is decreases
linearly with increasing production volume
for automatic assembly using special-
purpose machines.
5. In the case of robotic assembly, the
assembly cost per product decreases with
increasing production volume, but becomes
less economical after exceeding the annual
production volume at a certain point.
Cont..

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1. Assembly Automation and Product Design G. Boothroyd, Marcell Dekker, Inc. 1992
2. Product Design for Manufacture and Assembly G. Boothroyd and P. Dewhurst, Boothroyd
Dewhurst, Inc. 1989 Marcell Dekker, Inc. 1994
3. Mechanical Assemblies: Their design, manufacturing and role in product Development, D. E
Whitney, Oxford Press
4. Product Design for Assembly: The Methodology Applied G. Lewis and H. Connelly
References

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