Comparison of rotational turning and hard turning regarding surface generation

Abstract

In this paper, two different turning processes namely rotational turning and hard turning are compared to each other regarding surface generation aspects. By experiments it is shown that, with higher feed rates, rotational turning yields same surface quality as hard turning. Feed rates can be chosen six times higher in rotational turning than in conventional hard turning without losses in the surface roughness quality. Also experiments reveal that the tool wear in rotational turning has a beneficial effect on the surface roughness. A corresponding explanation model is thereby presented which takes the specific tool/work piece engagement in rotational turning into account. Furthermore, it is shown that rotational turning has negative effects on the surface integrity. The phase transformation zones (“white layers”) are thicker in rotational turned parts than in hard turned parts. Also the level of tensile residual stress in rotational turning is higher than in hard turning. Both effects are probably caused by high thermal material loads in rotational turning due to increased friction. However, the results of this paper show that rotational turning has a high potential to become an efficient alternative to hard turning, especially when it comes to large scale production of simple shaped parts.