Metal- forming processes involve the transfer of high tractions across the tool/workpiece interface while deforming plastically the workpiece to a desired shape. During the evolution of the workpiece shape, the sliding between tool and workpiece surface is accompanied by significant frictional forces and material wear that may result in degradation of important product surface attributes The increasing use of high tensile materials requires new forming dies that withstand the increased wear and tear. Casting moulds are rapidly degraded by cyclic thermal fatigue of the mould. It is not strictly a surface related problem but thermal fatigue. Al-alloy injection moulding. Moulds degrade by abrasive surface wear, causing rounding of wedges, increments in mould surface roughness, and crack formation. Cost effectiveness of forming die requires robust and hard-wearing tools to resist the increased abrasion and wear. In order to combine cost effective machining, well established base material for tools and a high ability to resist abrasion and deterioration a compound tool design can offer a solution.
High temperature manufacturing processes represent today a significant volume of the productivity for consume goods and components for other primary sectors (e.g. automotive).
This proposal aims at developing integrated solutions; tooling material optimisation and surface engineering, to maximise the performance of high temperature material processes, particularly focussing on: Cu-alloys casting and Al-alloy injection moulding. More specifically, Cu-alloy casting dies are rapidly degraded by cyclic thermal fatigue of the surface. In the case of Al –alloy injection moulding, dies degrade by abrasive surface wear, causing rounding of wedges, increments in mould surface roughness, and crack formation.
The conventional materials used for making tools (dies and punches) include alloy cast irons, tool steels and sintered carbides. The application of hard coatings has resulted in marked improvements in the useful life of forming tools. Coated tools also permit faster forming processes, therefore their use becomes more and more common. Lifetimes of over 10 million cycles have been obtained with appropriate coatings whereas non-coated tools would not survive one single cycle.
The long-term RTD effort invested in hard coatings development has lead to numerous commercial hard coated tool applications. Improvements of 100 to 200 times in tool durability have been reported by the use of binary compounds such as TiN, TiB2 and TiN/TiC for dies, punches and deep drawing tools. Self- lubricating coatings have been investigated to be in forming of non ferrous metals. For the large bulk of metal forming operations (deep drawing, stamping, fine blanking, cutting etc.), particularly of ferrous metals, lubricants are necessary in order to obtain a long tool life and high production speeds. The main limitations of self- lubricating coatings are: short tool life, because the coating functions as a sacrificial layer; they often require a ‘natural impurity’ (e.g. corrosion protection oils used for storage) as lubricant; they can currently be applied only for certain ‘difficult to cut’ metallic materials.