Resource Efficient Regrinding of Cemented Carbide Milling Tools

Abstract

Cemented carbide tools are often used for milling operations that cause high thermal and mechanical process loads, e.g. machining processes for titanium alloys. However, the disposal of those tools after one life cycle would significantly reduce their resource efficiency. Therefore, regrinding operations are crucial in order to recycle worn tools and ensure an economical as well as resource efficient manufacturing process. The main challenges during regrinding are the precise quantification of present defects and the subsequent determination of the grinding allowance. As it is, a worker performs both tasks using his individual estimations. Consequently, the estimated grinding allowance is often too low or too high. This either decreases the lifetime of the reground tools due to remaining defects or reduces the resource efficiency since more material than necessary is removed. This paper investigates the determination of the grinding allowance and the environmental impact of regrinding operations on the life cycle of the investigated tools. It is shown that about 12.5% percent of the worn tools are being unnecessarily disposed of. Furthermore, the resource efficiency of tools with small breakouts might be increased by 20% if the recommended allowance strategy is utilized. The tool wear of the grinding tools is also taken into consideration in order to further increase the resource efficiency of the whole life cycle, including milling tool and grinding wheel. The results show that small grain sizes and low grain concentrations are not suitable for efficient regrinding processes since higher wear and consequently higher geometrical inaccuracies of the reground tools occur.