Chapter 6 basic design for assembly
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Transcript of Chapter 6 basic design for assembly
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ME3101 / ME3102Mechanical Systems DesignChapter 6Basic Design for Assembly
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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
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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
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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.
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Minimize number of parts
Extracted from: http://www.cbpa.ewu.edu/~pnemetzmills/OMch3/omfac.html
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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.
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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
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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.
Do this!
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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.
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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 the correct alignment
Design for symmetry
Obvious Assymmetry
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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)
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