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2009
Conference Paper
Titel
Combined surface treatments increase lifetime of forging dies
Abstract
Forging dies are exposed to thermal, mechanical, tribological and chemical stress during use. This results in high abrasive and adhesive die wear which limits the die lifetime. The lifetime can be prolonged by means of appropriate surface treatments. Laser beam surface treatment techniques offer several advantages compared to conventional procedures: they allow an efficient, local modification of the surface layer which can be adjusted to the actual wear types. Within the research activities selected forging dies were laser alloyed/dispersed in order to reduce the abrasive wear. The dies were subsequently plasma nitrided to decrease the adhesive wear. The optimal combination of such surface treatments was determined via an iterative evaluation of alloying material, process development and die application under industrial conditions in forging companies. The findings up to now show that the die lifetime can be increased from 50% to 300%. Some areas of improvement still remain before this technique can be used at industrial level: the process know-how is insufficient as regards laser alloying/dispersing of specific die areas such as radii and edges; difference of results between nitriding processes (plasma, salt bath and gas nitriding) are not well-known in combination with laser pre-treated die surfaces at the moment; a classification of forging dies is required depending on die geometry, strain, material flow path, formed material, etc. The technology of laser alloying/dispersing needs to be made reliable, reproducible and accessible to the forging industry at reasonable costs. However, the results of this research are encouraging and are worth further investigation and development.