The UMass method of representing the efficiency of a product design is :
Design efficiency, E = N (H + A) / T
E = automatic assembly design efficiency
N = theoretical minimum number of parts
H = automatic handling cost per part
A = automatic assembly cost per part
T = total operation cost
A 100% efficient product design has the following qualities :
- It uses the theoretical minimum number of parts
- The number of insertion operations equals to the theoretical minimum number of parts
- The difficulty level in feeding is similar to feeding a 2.5 cm cube at 1 per second
- The difficulty level of insertion is similar to that of inserting a standard part at 1 per second
Well designed products have UMass design efficiencies between 20% and
30%. Poorly designed products have efficiencies less than 5%.
Alternative product designs can be compared, in terms of design
efficiency, to obtain the most economic design.