In this paper some models for the calculation of optimum machining conditions on automatic mono-and multi- spindle lathes are proposed. The available digital computers and the related computational techniques allow extending the studies, previously developed for the optimization of simple rough-turning operation, to more sophisticated problems. In this way the optimum determination of the machine-tool, of the working cycle and of the set of cutting parameters can be carried out with expenses which generally do not affect considerably the price of the product.