A new algorithm for minimising the surplus parts in selective assembly

Selective assembly is a normally accepted method for producing high precision assembly from relatively low precision components. The accuracy of selective assembly is mainly based on the number of groups (fixed before and during assembly) and the range of a group (allocated equally on the design tolerance. However, there are often surplus parts in some groups due to the imbalance of mating parts, especially in the cases of undesired dimensional distributions. Aiming at minimising the surplus parts, this paper presents a new algorithm to group the mating parts based on the ideas of balanced probability and unequal tolerance range in each group. The methodology developed in this work provides a feasible means to avoid the unexpected loss of production cost as the surplus parts can be reduced to their minimum.