A Fuzzy System for the Estimation of Machining Times

Machining time is an important factor in the direct production costs of many mechanical parts, and for determining feasible delivery dates. Early estimation of the costs and timing of machined parts is of the utmost importance to manufacturing firms, since it can drive bidding strategies, management of resources, and other production policies crucial to the economic success of the company. While for mass production, a detailed process economic analysis is necessary, for small production runs, the time spent in detailed study and simulation may not justify the potential saving. A prototype of a fuzzy engineering based expert system was designed to estimate the machining times. The system interrogates the engineer about some fuzzy features of the machining processes required for a part, such as cutting speed, required surface quality, and part's complexity. The fuzzy expert system uses 18 rules for setup time and for machining time estimation. The machining times of an actual part with 11 different processing steps were estimated with the fuzzy expert system. The estimates compared favorably with the estimates provided with a detailed simulation of the machining processes.