Design for assembly

Question 1

What is DfA

Answer 1

A part of DfM - reduce costs of assembly

Question 2

Explain DfA for manual assembly

Answer 2

• Reduce parts and part number
• Facilitate access and visibility during insertion
• Minimize the need for reorientation
• Eliminate assembly faults

Question 3

Explain DfA for automatic assembly

Answer 3

Part handling
- seperation, feeding, transportation
Insertion
- no holding, add chamfers, assemble from one direction with small force

Question 4

What is the ideal assemblly characteristics for parts when maximising the ease of assembly?

Answer 4

The part is:

• inserted from the top of the assembly
• self-aligning
• does not need to be oriented
• Requires only one hand for assembly
• is assembled in a single linear motion

Question 5

When estimating the theoretical minimum number of parts - what three questions do you ask about each part?

Answer 5

1. During the operation of the product, does the part move relative to all other parts already assembled?
2. Must the part be of a different material than or be isolated from all other parts already assembled?
3. Must the part be separate from all other parts already assembled because otherwise neccessary assembly or disassembly of other seperate parts would be impossible?

Question 6

What is the Boothroud & Dewhurst DFA method?

Answer 6

A technique that provides a systematic way of performing DFA and how to calculate a “design efficiency”.

Question 7

Explain the two important steps for each part in the assembly according to Boothroyd and Dewhurst method

Answer 7

1. A decision on whether the part can be a candidate for elimination or combined with other parts in the assembly
2. An estimation of the time taken to grasp, manipulate and insert the part

Question 8

What is the technique DFA method from Boothroyd and Dewhurst based upon?

Answer 8

Collecting data from two charts estimating the time for handling and insertion of each part of the product/assembly