Research of the tool wear process by finite element method

Dolyniak Y.
Material wear processes are found at all places where materials are in mechanical contact with each other. Wear is often present as combinations of several different physical wear mechanisms and the ones most likely to be present during mechanical contact are: abrasive, adhesive, diffusive, chemical, and wear due to plastic deformation. The dominating wear mechanism depends on the surfaces, the contact area between them, materials, topography, hardness, etc. The extent of cutting tool wear depends on the tool material and geometry, workpiece material, cutting parameters, cutting fluids and machine-tool characteristics. The wear land of the cutting tool insert is the area of the cutting tool, near the cutting edge, were the insert is worn during machining. Two basic areas of tool wear are flank wear and crater wear, but several other mechanisms also occur . Tool lifetime is often measured in terms of crater or flank wear according to ISO 3685:1993. The main objective with creating wear models is to try to describe how different types of tool wear progress in time and also create understanding about how different cutting parameters affects the wear process. There exist a number of different wear models; it is possible to split many of these models in to two groups. One of them is a group of models that predict the tools lifetime depending on cutting conditions, based on empirical formulas. The other one is models that predict the volume wear rate depending on cutting conditions. This article focus on the second group that predict the volume wear rate, because this kind of model implements well with modern FE-software’s to simulate tool wear and tool life on complex geometries. The most common used model of this kind is the one that Usui [1] derived. This model is supposed to describe adhesive and diffusive wear in one term. One difficulty in developing an analytical model for tool wear is the effect of changing tool geometry on that wear. As the tool wears, the pressure, temperature and material flow across the surface hanges. Finite element analysis (FEA) can help model the effects of changing tool geometries by using discrete elements and nodes in the application of wear rates. Third Wave System’s software AdvantEdge is a FEA program for machining processes, calculating both stresses and temperatures. These simulations have the capability to model tool wear by applying calculated wear rates to the nodes in contact with the workpiece or chip or Usui wear model.
Friday, February 17, 2017
Friday, February 17, 2017