Model-based cost analysis of lapping process

Lapping is an abrasive surface finishing process in which fine, charged abrasive particles are embedded into a soft lap to remove material from the surface of a workpiece. The total cost associated with lapping process is affected by a number of parameters such as lap plate size, abrasive type, and work-piece material etc. A meaningful cost model needs to consider all these parameters when deriving process cost estimates. This paper presents a cost model for lapping based on cost estimates of process parameters, process simulation and modeling, and cost analysis. Two models are proposed for lapping process. The first is a simulation model of the lapping process developed using ARENA 10.0, a process oriented simulation software, to attain the annual yield/production for different processing combinations, various abrasive sizes and types, and lapping time. The second is a cost model (CM) that will compute the total variable, fixed and labor costs associated with lapping process. The CM is implemented in Microsoft Excel and presented with an optimization technique using non-linear Mixed Integer Programming (MIP), to aid the selection of the process, labor, and abrasive size and type. A case study is presented to demonstrate the technique.