Cost optimization for the slitting of core laminations for power transformers

The successful realization of a project for slitting core laminations for power transformers under minimizing costs is presented. The production of the core of power transformers requires great amounts of grain oriented silicon steel (up to 200 tons for a single transformer). The shape of the cross section of the core is approximated to a circle by stacking sheets of different widths. To supply these sheets, coils of given lengths and widths are to be slit following a cutting plan that minimizes the costs. The authors describe an efficient solution method which is based on the solution of various knapsack problems.