Design for Assembly (DFA) is a team based product design evaluation tool which through simple structured analysis gives the information required by designers to achieve the following benefits.
The evaluation is carried out by the following method as shown on the flow chart.
By interrogation of component parts through the methodology, each can be classified as essential ‘A’ parts or non-essential ‘B’ parts. Given this awareness, re-designs can be evolved around the essential components.
All component parts must have the correct orientation before the assembly can take place. The difficulty of achieving this can be assessed and components receiving high ratings can then be modified to give an acceptable rating. Poka-Yoke devices can be installed in the manufacturing process to ensure zero defects from this source.
To assist the analysis process an assembly flowchart is constructed and the difficulty of assembling each part in the sequence can be rated using the DFA databases. Difficult assembly tasks and non-value-added processes are revealed for correction by re-design. Simple concepts such as the ability to assemble in layers from above can result in major cost saving at the manufacturing stage.
Each of the above stages in the methodology have the following measures of performance which are accepted as an indication of good design.
| Ø Functional analysis gives a Design Efficiency | = | Essential Parts | = > 60% | |
| Total parts | ||||
| Ø Handling analysis gives a Handling Ratio | = | Total Ratings | = < 2.5 | |
| Total parts | ||||
| Ø Assembly analysis gives an Assembly Ratio | = | Total Ratings | = < 2.5 | |
| Total parts | ||||
Typical results achieved by application of the DFA technique to date are as follows:
| Ø Parts count reduction | 30% | |
| Ø Assembly cost reduction | 40% | |
| Ø Product cost reduction | 35% |
Note: Fewer parts means also: