Modelling in selective assembly with symmetrical interval-based Taguchi loss function for minimising assembly loss and clearance variation

The functional performance of an assembled product depends upon its component tolerance and assembly clearance. For producing components with tight tolerance, advanced machining process may be required but it will increase the product cost. In any manufacturing process, final step is assembly and plays a vital role in determining the product quality. The selective assembly is a method of assembly that provides an effective way for producing high precision product from low precision components. The conventional Taguchi's loss function targets on a single value but in real situations an interval of values will be essential. To overcome this issue, a symmetrical interval-based Taguchi (SIT) loss function is proposed in this paper and it is applied into the selective assembly method to evaluate the assembly loss. Also, an improved sheep flock heredity (ISFH) algorithm is proposed to obtain the best combination of selective group with minimum clearance variation and least assembly loss value.