University of Baghdad
Al-Khwarizmi College of Engineering
Automated Manufacturing Engineering
Department
Design for Manufacturing
By : Omer Chasib k.
2014
Purpose Statement
To provide an overview of Design for
Manufacturing and Assembly (DFMA)
techniques, which are used to minimize
product cost through design and process
improvements.
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.
‘Optimization of the
manufacturing
process…’
DFA 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.
Major DFM objectives
1)
2)
3)
4)
5)
Estimate the mfg. costs
Reduce the costs of components
Reduce the costs of assembly
Reduce the costs of supporting production
Consider the impact of DFM decisions on other
factors.
Design for Assembly
Definition: DFA is the method of design of the
product for ease of assembly.
‘…Optimization
of the part/system
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.
Differences
Design for Assembly (DFA)
• concerned only with reducing product assembly
cost
▫ minimizes number of assembly operations
▫ individual parts tend to be more complex in design
Design for Manufacturing (DFM)
• concerned with reducing overall part production
cost
▫ minimizes complexity of manufacturing operations
▫ uses common datum features and primary axes
Similarities
• Both DFM and DFA seek to reduce material,
overhead, and labor cost.
• They both shorten the product development cycle time.
• Both DFM and DFA seek to utilize standards to reduce
cost
Terminology
Design for Manufacturing (DFM) and Design for
Assembly (DFA) are now commonly referred to as a
single methodology, Design for Manufacturing and
Assembly (DFMA) .
Sequence of Analysis
Concept Design
Design for
Assembly
Design for
Manufacturing
Detailed Design
Design for Manufacturing (DFM) and design for
assembly (DFA) are the integration of product
design and process planning into one common
activity.
The goal is to design a product that is easily and
economically manufactured.
The heart of any design for manufacturing system is a
group of design principles or guidelines that are
structured to help the designer reduce the cost and
difficulty of manufacturing an item. The following is a
listing of these rules
Reduce the total number of parts
The reduction of the number of parts in a product is probably the best
opportunity for reducing manufacturing costs. Less parts implies
less purchases, inventory, handling, processing time, development
time, equipment, engineering time, assembly difficulty, service
inspection, testing
Develop a modular design
The use of modules in product design simplifies
manufacturing activities such as inspection, testing,
assembly, purchasing, redesign, maintenance, service
Use of standard components
Standard components are less expensive than custommade items. The high availability of these components
reduces product lead times.
Design parts to be multi-functional
Multi-functional parts reduce the total number of parts in
a design, thus, obtaining the benefits given in rule 1.
Some examples are a part to act as both an electric
conductor and as a structural member, or as a heat
dissipating element and as a structural member.
Design parts for multi-use
In a manufacturing firm, different products can share
parts that have been designed for multi-use. These parts
can have the same or different functions when used in
different products.
In order to do this, it is necessary to identify the parts that
are suitable for multi-use. For example, all the parts used
in the firm (purchased or made) can be sorted into two
groups: the first containing all the parts that are used
commonly in all products.
Design for ease of fabrication
Select the optimum combination between the material and
fabrication process to minimize the overall
manufacturing cost. In general, final operations such as
painting, polishing, finish machining, etc. should be
avoided. Excessive tolerance, surface-finish requirement,
and so on are commonly found problems that result in
higher than necessary production cost.
Avoid separate fasteners
The use of fasteners increases the cost of manufacturing a
part due to the handling and feeding operations that
have to be performed. Besides the high cost of the
equipment required for them, these operations are not
100% successful, so they contribute to reducing the
overall manufacturing efficiency. In general, fasteners
should be avoided and replaced, for example, by using
tabs or snap fits.
Fastener Cost
Select the •
screwing
most
inexpensive
riveting
fastening
method
required
plastic bending
snap fit
General Design Principles
Self-fastening features
Minimize assembly directions
All parts should be assembled from one direction. If
possible, the best way to add parts is from above, in a
vertical direction, parallel to the gravitational direction
(downward).
In this way, the effects of gravity help the assembly
process, contrary to having to compensate for its effect
when other directions are chosen.
General Design Principles
Top-Down Assembly
Handling Difficulty
•
•
•
•
•
•
•
Size
Thickness
Weight
Fragility
Flexibility
Slipperiness
Stickiness
Handling Difficulty
size
sharpness
slipperiness
flexibility
Ensure parts do not need to be held in position
Reference
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. Design and Analysis of Manufacturing Systems
Prof. Rajan Suri University of Wisconsin 1995
4. Product Design for Assembly: The Methodology Applied
G. Lewis and H. Connelly