Minimizing the number of tool switches on a flexible machine

Y. Crama, A.W.J. Kolen, A.G. Oerlemans, F.C.R. Spieksma

Research output: Contribution to journalArticleAcademicpeer-review

124 Citations (Scopus)


This article analyzes a tool switching problem arising in certain flexible manufacturing environments. A batch of jobs have to be successively processed on a single flexible machine. Each job requires a subset of tools, which have to be placed in the tool magazine of the machine before the job can be processed. The tool magazine has a limited capacity, and, in general, the number of tools needed to produce all the jobs exceeds this capacity. Hence, it is sometimes necessary to change tools between two jobs in a sequence. The problem is then to determine a job sequence and an associated sequence of loadings for the tool magazine, such that the total number of tool switches is minimized. This problem has been previously considered by several authors; it is here revisited, both from a theoretical and from a computational viewpoint. Basic results concerning the computational complexity of the problem are established. Several heuristics are proposed for its solution, and their performance is computationally assessed.

Original languageEnglish
Pages (from-to)33-54
Number of pages22
JournalInternational Journal of Flexible Manufacturing Systems
Issue number1
Publication statusPublished - Jan 1994
Externally publishedYes


  • computational complexity
  • heuristics
  • sequencing
  • tool management


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