A correlation and heuristic approach for obtaining production sequences requiring a minimum of tool replacements

This research presents a technique to obtain production sequences requiring minimal tooling replacements, via exploitation of statistical metrics along with a heuristic approach. Tool preservation has always been an important issue, and in many cases, since the production of some products tends to wear the tooling differently than others, the production sequence plays an important role in this preservation. Thus, if tool preservation is a priority then maintaining uniform tool-wear through careful product sequencing should be of concern. In some industries, minimizing tool replacement by increasing its useful life can result in large annual savings for manufacturing firms-due to increased tool life, reduction of unscheduled downtime, and increased flexibility of the machining center. This research presents sequencing techniques that attempt to minimize the number of tool replacements on a single machine over a given period of time (via sequences which have uniformity of tool wear). The sequences are obtained via simulated annealing, with a measurement criterion of three correlation-related statistics. Experimentation indicates that sequences obtained via the presented metrics and simulated annealing provide fewer tooling replacements as compared to more conventional sequencing methods. Scheduling of production has many objectives-minimization of in-process inventory and minimization of idle time are two of the more popular objectives. Scheduling production in a way to minimize tool wear, and subsequent tooling replacement is a scheduling objective that has seen relatively little attention in the literature. As a result, the authors feel compelled to offer the presented methodology addressing real-world scheduling problems with the objective of minimizing tooling replacements. Minimization of tooling replacements is especially critical if the tooling medium is of high value (i.e., industrial grade diamonds, or carbide cutting tips), because the amount of money saved can be sizeable.