Selective assembly is an economic method to obtain perfect precision assemblies by using the components manufactured with wide tolerance specifications. The mating component's tolerances are divided into equal number of groups. The manufactured components are segregated according to these groups and the components from the corresponding groups are assembled interchangeably in the conventional method. The required clearance can be achieved at this assembly method that is tighter than those

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... ed at the normal fabrication method with lowest total cost. Still there are more variations in the clearance range. In this paper, a new optimization method is proposed to find the best combination of the selective groups to minimize assembly variation for the complex assemblies. A case example is analyzed for piston, cylinder and piston ring assembly. Fuzzy evolutionary programming (EP) method is used to obtain the best combination of the selective groups to control the assembly variation. Selective assembly is successfully applied for a piston and cylinder assembly using fuzzy EP method to achieve minimum clearance variation without sacrificing the benefit of wider tolerance in manufacturing.