Search

Under given conditions, time and feed dependent fracture is the predominant failure mechanism of cutting tools. Assuming as a first approximation a decay in fracture resistance linear with cutting time, a model is developed which describes the overall variation in terms of variation in tool life (at constant feed) and fracture resistance (estimated from increasing feed tests). Validation of the model and quantitative evaluation of parameters are obtained from a set of cutting tests performed on a CNC lathe both at constant and variable feed rate. The effects on the model of single and combined variation of the main parameters are examined, and the main implications of the tradeoff between material removal rate and hazard function are discussed.

Master Production Scheduling is a cornerstone of MRP II systems, since it represents the link between marketing and production. To overcome the limitations of MRP II systems, we aim at finding a good and realistic MPS by optimization techniques, rather than by a trial-and-error manual procedure. Due to the complexity of the resulting mathematical model, heuristic solution strategies must be devised. In this paper we report computational experiments on the application of approximate solution methods, based on Linear Programming, to a simplified version of the problem, namely the Capacitated Lot-Sizing Problem (CLSP). We show the usefulness of suitable model reformulations and of interior point solution methods.

The main design principles and specifications of an experimental vertical boring mill built for high speed turning tests (up to over 100 m/s) are described, and some results of an investigation on turning steel with ceramic tool within a 15 to 50 m/s cutting speed range are discussed. Data on single and combined effects of machining parameters on surface finish, tool life, chip formation and cutting power were obtained in the tests, and their significance is assessed.