Feed Modulation Assisted Machining for Chip Breaking in Hard Turning of AISI 52100 Bearing Steel

During turning operations, continuous chip formation leads to chip accumulation between the tool and workpiece, damaging the surface and reducing productivity due to frequent manual removal. This issue is critical during hard turning of AISI 52100 bearing steel, as the thermomechanical loads cause severe softening of the chip material, making chip breaking a real challenge. The use of feed-modulated machining (F-MAM) is proposed in various studies to achieve chip breakage during turning operations. However, this generates variable loads that may make it unsuitable during hard turning processes. This study analyses the effectiveness of F-MAM during hard turning of AISI 52100 bearing steel, evaluating its ability to generate discontinuous chips, together with the effect on tool wear and the quality of the generated part. The analysis combines experimental tests carried out under different cutting conditions and modulation amplitudes with a theoretical evaluation using a mechanistic model for the machining process, which simulates the theoretical machined surface and the chip load generated during turning. The results show a significant improvement in chip fragmentation and evacuation when using the F-MAM strategy, at the expense of poorer surface roughness and slightly higher tool wear. Theoretical analysis reveals a strong correlation between the mechanical model simulations and the experimental results, both in terms of tool wear and surface roughness evolution, indicating the mechanistic model’s ability to provide a valuable tool for planning the hard turning process when using the F-MAM technique for chip breaking.