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2.3 MECHANICAL ENGINEERING
Metal forming applications are, by their very nature, taxing on the tools and machines used to achieve a finished component. Material degradation and wear is of critical importance in any such operation as a failing in the tool or machine has the potential to cause health hazards and/or significant monetary losses. The wear of material is due to the contact of two opposing surfaces and their subsequent motion relative to each other. It can take many forms some examples of which are: a two or three body abrasive type, a rolling fatigue type or an adhesion type.
Much research has been done in the area of surface treatment for cutting and forming tools; with the aim of preventing premature failure of components in mechanical processes. Of particular interest are the PVD and CDV approaches to surface treatment, both of which have held prominent positions in this field for the last two decades. In the metal forming area research has ranged from production of low-friction coatings for sheet metal forming to coatings designed for high hardness in metal cutting applications.
A large percentage of researchers aim to improve or optimise a coating; concentrating on performance in a particular area of interest (e.g. frictional performance) or for a particular application (e.g. milling tools). To achieve this extensive knowledge of the variables influencing coating quality is essential. The characteristics of the coating produced depend primarily on the materials selected, the deposition process, the substrate being coated and on post/pre treatment of the coatings. These areas can be further refined to produce a more comprehensive list of coating parameters. Optimisation of the coating must be guided by an analysis of these parameters; this analysis should influence material selection and also the selection of deposition parameters.
To supplement practical experiments, computational techniques have been used extensively to increase the understanding of these coatings; both the material deposition and the material breakdown during operation. These investigations have ranged from improvement of the deposition processes to modelling voids and inclusions in the coating. The complexity of coating technology is reflected in the diversity of studies to be found in the literature.
The aim of this work is to review recent developments in PVD and CVD coatings with specific focus on those utilised to enhance the performance and working life of punch and die sets.
Montgomery, S., Kennedy, D., O'Dowd, N.: PVD and CVD Coatings for the Metal Forming Industry. Matrib 2010, Croatia.