Optimum Tolerance Synthesis for Complex Assembly with Alternative Process Selection Using Bottom Curve Follower Approach

Components cannot be manufactured according to the required nominaldimensions due to inherent variations in workmanship, materials and machinetools. Tolerance specification of part dimensions affects the performance, qualityand cost of a product. The proper distribution of tolerance, known as toleranceallocation, reduces the manufacturing cost of a product. Thus, researchers in thisfield are keenly interested in tolerance allocation. The choice of alternativeprocesses for tolerance allocation also plays a vital role in reducingmanufacturing costs. Near-optimal allocated tolerances are obtained using nontraditionaloptimization techniques, in which solutions are randomly achieved.However, there is the possibility that a better allocation process will not bediscovered because the randomness of the results of successive runs will notyield consistent results. In this work, an attempt has been made to solve theabove problem using the Lagrange multiplier (LM) method for complex assemblyand the bottom curve follower approach. The methodology has beendemonstrated on a wheel mounting assembly. Compared to Singh’s method [14],a 1.95% savings in manufacturing cost was achieved after implementing theproposed method. The present method was 30 times faster than the existingmethods.