2. DFA – Design for Assembly
In the previous chapter, we have
talked about DFM, Design for
Manufacturing.
In this chapter, we will go through
DFA, Design for Assembly.
Similarly, DFA occurs through the
entire design process, from the start,
till actual production
3. DFA – Design for Assembly
Generally accepted guidelines for
DFA:
•Minimize number of parts
•Feature lesser assembly movements
•Provide Self Aligning features
•Eliminate visual obstructions to
assembly
•Reduce number of tools required
•Use symmetrical parts
4. Minimize number of parts
Similar to DFM, a reduction in number of parts is a rule of
thumb to follow for Design for assembly.
Lesser parts = Lesser steps required for assembly
We will illustrate this concept in the next slide.
5. Minimize number of parts
Extracted from: http://www.cbpa.ewu.edu/~pnemetzmills/OMch3/omfac.html
6. Lesser assembly movements
To reduce assembly time,
designers can take into
consideration a “top-down
approach to design” and have
features in the same orientation.
This reduces the need to re-
orientate the main body during
assembly.
7. Provide Self Aligning Features
Compare the 2 diagrams below.
The design on the left requires more effort to align the parts together.
The design on the right however, has a self aligning feature that allows
the part to fit together easily, thus reducing assembly time
No self aligning feature Integrated self aligning feature
8. Eliminate Visual Obstructions
Look at the 2 diagrams on the left.
As a designer, take note to prevent visual
obstruction of assembly features.
Blocking visual sight of assembly features
increases the difficulty in assembly and thus
increases time required.
9. Reduce Number of Tools Required
Another simply rule of thumb for
designers to follow is to reduce the
number of tool variants required.
For example, the same kind of
fasteners can be used to reduce the
number of tools required to fasten
them.
10. Use Symmetrical Parts
Whenever possible, part designs
should feature symmetry to reduce
time spent on alignment during
assembly.
However, where symmetry is not
possible to attain, obvious asymmetry
is preferred for easy identification of
Design for symmetry the correct alignment
Obvious Assymmetry
11. In conclusion…
Designers should always take into
consideration the practicality of their
product.
While the product has to be usable and
efficient, it has to be able:
•to be manufactured (DFM)
•to be assembled efficiently (DFA)
