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DFA - Design for Assembly index

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The Design for Assembly Index (DFA-index) indicates how easy it is to assembly a component and can be expressed as:

DFA = 100 Nm tm / ta                            (1)


DFA = Design for Assembly Index

Nm = theoretical minimum number of parts

tm = minimum assembly time per part (s)

ta = estimated total assembly time (s)

Example - Assembling Components with Ideal Design

With an ideal design there is a minimum of parts and no assembly difficulties. The ideal DFA-index for assembling one component in one second can be calculated as

DFA = 100 (1) (1 s) / (1 s) 

      = 100   

Example - Assembling a Component from Parts

A component requires 200 seconds in total to assemble. The are 6 parts and the minimum assembly time per part is 3 seconds.

The DFA-index for this component can be calculated as

DFA = 100 (6) (3 s) / (200 s) 

      = 9   

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