This document provides an overview of Design for Assembly (DFA) techniques. It defines DFA as designing products for ease of assembly to minimize assembly costs. The document outlines the objectives and differences between DFA and Design for Manufacturing (DFM). It then describes the DFA process, which involves analyzing a product's design to minimize part count, simplify handling and insertion of parts, and reduce secondary operations. Guidelines are provided for applying DFA principles to optimize a product's design for assembly.

1. DFA:SOP
Design for Assembly
Prepared by: Udayraj M.

2. • Statement
• Objective
• DFA & DFM
• Difference
• Similarities
• Terminology
• Sequence of Analysis
• Design for Assembly Principles
• DFA Process
• DFA Analysis Worksheet
• DFA Guidelines
• Key DFMA Principles
CONTENT

3. To provide an overview of Design for Manufacturing and
Assembly (DFMA) techniques, which are used to minimize
product cost through design and process improvements
STATEMENT

4. o Differences and Similarities between Design for Manufacturing and
Design for Assembly
o Describe how product design has a primary influence
o Basic criteria for Part Minimization
o Quantitative analysis of a Design’s efficiency
o Critique product designs for ease of assembly
o The importance of involving production engineers in DFMA analysis
OBJECTIVE

5. Design for Assembly
Definition: DFA is the method of design of the
product for ease of Assembly
DFA is a tool used to assist the design teams in
the design of products that will transition to
productions at a minimum cost, focusing on the
number of parts, handling and ease of assembly.
Design for Manufacturing
Definition: DFM is the method of design for ease of
Manufacturing of the collection of parts that will form
the product after assembly
DFM is a tool used to select the most cost effective
material and process to be used in the production in
the early stages of product design.
DFA & DFM
Optimization of the
manufacturing process…’
Optimization of the part/system
assembly…’

6. Design for Assembly (DFA)
concerned only with reducing product assembly cost
o minimizes number of assembly operations
o individual parts tend to be more complex in design
Design for Manufacturing (DFM)
concerned with reducing overall part production cost
o minimizes complexity of manufacturing operations
o uses common datum features and primary axes
DIFFERENCE

7. Both DFM and DFA seek to reduce material, overhead, and labor cost.
o They both shorten the product development cycle time.
o Both DFM and DFA seek to utilize standards to reduce cost
SIMILARITIES

8. Design for Manufacturing (DFM) and Design for Assembly (DFA) are
now commonly referred to as a single methodology, Design for
Manufacturing and Assembly (DFMA).
TERMINOLOGY

9. Concept Design
Design for
Assembly
Design for
Manufacturing
Detailed Design
SEQUENCE OF ANALYSIS

10. Minimize part count
o Design parts with self-locating features
o Design parts with self-fastening features
o Minimize reorientation of parts during assembly
o Design parts for retrieval, handling, & insertion
o Emphasize ‘Top-Down’ assemblies
o Standardize parts…minimum use of fasteners.
o Encourage modular design
o Design for a base part to locate other components
o Design for component symmetry for insertion
DESIGN FOR ASSEMBLY PRINCIPLES

11. Step3
Step2
Step4
Step1
Step5
Product
Information:
functional
requirements
Functional
analysis
Identify parts
that can be
standardized
Determine
part count
efficiencies
Step6
Determine
your practical
part count
Step7
Identify
quality
(mistake
proofing)
opportunities
Identify
handling
(grasp &
orientation)
opportunities
Identify
insertion
(locate &
secure)
opportunities
Identify
opportunities
to reduce
secondary
operations
Analyze data
for new
design
DFA PROCESS

12. DFA ANALYSIS WORKSHEET

13. Step 1
Product Information: functional
requirements
o Functional analysis
o Identify parts that can be standardized
o Determine part count efficiencies
Considerations/Assumptions
o The first part is essential (base part)
o Non-essential parts:
a.Fasteners
b.Spacers, washers,
c.O-rings Connectors, leads
o Do not include liquids as parts
(e.g.. glue, gasket sealant, lube)

14. Part Identification
o List parts in the order of
assembly
o Assign/record part number

15. Count Parts & Interfaces
o List number of parts (Np)
o List number of interfaces (Ni)

16. Determine Theoretical Min. No.
of Parts

17. Determine if Parts Can be
Standardized
o Can the current parts be standardized?:
–Within the assembly station
–Within the full assembly
–Within the assembly plant
–Within the corporation
–Within the industry
o Should they be?
o (Only put a “Y” if both answers are yes…)

18. Theoretical Part Count
Efficiency
Theoretical part count efficiency=
𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 min 𝑛𝑜.𝑝𝑎𝑟𝑡𝑠
𝑡𝑜𝑡𝑎𝑙 𝑛𝑜 𝑜𝑓 𝑝𝑎𝑟𝑡𝑠
*100
Theoretical part count efficiency=
8
72
*100
Theoretical part count efficiency= 11.11 %
Rule of Thumb – Part Count Efficiency Goal > 60%

19. DFA Complexity Factor –
Definition
o Cummins Inc. metric for assessing complexity of a product
design
o Two Factors
Np – Number of parts
Ni – Number of part-to-part interfaces
a) Multiply the two and take the square root of the total
b) This is known as the DFA Complexity Factor

20. Determine Relative Part Cost
Levels
o Subjective estimate only
o Low/Medium/High relative to other parts
in the assembly and/or product line

21. Step 2
Determine Practical Minimum
Part Count
o Team assessment of practical changes
o Tradeoffs between part cost and
assembly cost

22. If more than 1/3 of the components in a product are fasteners, the assembly logic
should be questioned
Component Elimination
Example: Rollbar Redesign

23. Step 3
Identify quality (mistake
proofing) opportunities
Mistake Proofing Issues
o Cannot assemble wrong part
o Cannot omit part
o Cannot assemble part wrong way
around

24. Step 4
Identify handling (grasp &
orientation) opportunities
Handling Difficulty
Quantitative criteria
o Handling Time: based on assembly
process and complexity of parts
a) How many hands are required?
b) Is any grasping assistance needed?
c) What is the effect of part symmetry
on assembly?
d) Is the part easy to align/position?

25. Step 5
Identify insertion (locate &
secure) opportunities
Insertion Issues
Quantitative criteria
o Insertion time: based on difficulty
required for each component
insertion
a) Is the part secured immediately upon insertion?
b) Is it necessary to hold down part to maintain
location?
c) What type of fastening process is used?
(mechanical, thermal, other?)
d) Is the part easy to align/position?
Ensure parts
do not need
to be held in
position
Provide self-
aligning &
self locating
parts
Parts are
easy to
insert.
Provide
adequate
access and
visibility

26. Step 6
Identify opportunities to reduce
secondary operations
Eliminate Secondary Operations
o Re-orientation (assemble in Z axis)
o Screwing, drilling, twisting, riveting,
bending, crimping.
o Welding, soldering, gluing.
o Painting, lubricating, applying liquid or
gas.
o Testing, measuring, adjusting

27. Analyze data for new design

28. In order of importance: DFA Guidelines
o Reduce part count & types
o Ensure parts cannot be installed incorrectly
o Strive to eliminate adjustments
o Ensure parts self-align & self-locate
o Ensure adequate access & unrestricted vision
o Ensure parts are easily handled from bulk
o Minimize reorientation (assemble in Z axis) & secondary operations during assembly
o Make parts symmetrical or obviously asymmetrical
DFA GUIDELINES

29. o Minimize Part Count
o Standardize Parts and Materials
o Create Modular Assemblies
o Design for Efficient Joining
o Minimize Reorientation of parts during Assembly and/or Machining
o Simplify and Reduce the number of Manufacturing Operations
o Specify ‘Acceptable’ surface Finishes for functionality
KEY DFMA PRINCIPLES

30. Thank you