Günay Mustafa, Korkmaz Mehmet Erdi
Department of Mechanical Engineering, Faculty of Engineering, Karabük University, 78050 Karabük, Turkey.
Materials (Basel). 2024 Apr 16;17(8):1826. doi: 10.3390/ma17081826.
Although chip morphology changes according to the machining method and related cutting parameters, chip formation affects the quality of the machined surface. In this context, it is very important to understand the relationship between chip morphology and surface quality, especially in materials that are difficult to machine. In the presented study, the changes in chip morphology, surface morphology, and surface quality criteria (Ra and Rz) that occurred during the milling of precipitation-hardened steel in different cutting environments were analyzed. Milling experiments were carried out in dry, MQL (minimum quantity lubrication), nano-MQL (graphene), nano-MQL (hBN), Cryo, and Cryo-MQL environments using TiAlN-coated inserts and three different cutting speeds and feed rates. While the highest values in terms of Ra and Rz were measured in dry machining, the minimum values were obtained in a nano-MQL (hBN) cutting environment. Due to the lubrication and low friction provided by the MQL cutting environment, chips were formed in thinner segmented forms. This formation reduced the chip curve radius and thus provided a more stable surface morphology. On the other hand, Cryo-ambient gas could not effectively leak into the cutting zone due to the intermittent cutting process, but it increased the brittleness of the chips with the cooling effect and provided a similar surface morphology. The values of minimum Ra and Rz were obtained as 0.304 mm and 1.825 mm, respectively, at a 60 m/min cutting speed and 0.04 mm/rev feed. Consequently, the use of nano-MQL cutting medium is seriously recommended in terms of surface quality in milling operations of difficult-to-machine materials.
尽管切屑形态会根据加工方法和相关切削参数而变化，但切屑形成会影响加工表面的质量。在这种情况下，了解切屑形态与表面质量之间的关系非常重要，尤其是在难加工材料中。在本研究中，分析了在不同切削环境下对沉淀硬化钢进行铣削时切屑形态、表面形态和表面质量标准（Ra和Rz）的变化。使用TiAlN涂层刀片以及三种不同的切削速度和进给率，在干式、微量润滑（MQL）、纳米MQL（石墨烯）、纳米MQL（hBN）、低温切削和低温MQL环境中进行了铣削实验。虽然在干式加工中测得的Ra和Rz值最高，但在纳米MQL（hBN）切削环境中获得了最小值。由于MQL切削环境提供的润滑和低摩擦，切屑以更薄的分段形式形成。这种形成减小了切屑曲线半径，从而提供了更稳定的表面形态。另一方面，由于间歇切削过程，低温环境气体无法有效地泄漏到切削区域，但它通过冷却作用增加了切屑的脆性，并提供了类似的表面形态。在切削速度为60 m/min和进给量为0.04 mm/rev时，最小Ra和Rz值分别为0.304 mm和1.825 mm。因此，就难加工材料的铣削加工表面质量而言，强烈推荐使用纳米MQL切削介质。
