Design for Assembly Index indicates how easy it is to assembly a component.
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)
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)