In a mechanical workshop a CNC-machining centre is used to perform a large number of point operations on one or more workpieces in a clamp. Both the sequence of point operations and the method of clamping have a strong impact on the total amount of time that is needed to complete each workpiece. In this paper we analyse the efficiency of two clamping methods in the production of automotive engine blocks. The efficiency of these clamping methods is measured in terms of time, which is minimized by determining the optimal sequence of operations required for each method of clamping. A modification of a TSP algorithm has been employed to determine these optimal sequences.