OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 4 2024 Introduction The search for new processing methods that can achieve high surface quality and improve mechanical properties is currently of great interest. One such method is roller burnishing. It is aimed at improving the surface quality and dimensional accuracy of various metals. This process uses a hard roller to smooth out surface irregularities, resulting in a shiny fi nish. It can also make the material harder at the micro level [1]. Many industries use aluminum alloy 6061-T6 (Al 6061-T6) because it is strong yet lightweight, easy to work with, and does not rust. But getting the best surface quality and mechanical properties from Al 6061-T6 can be challenging using old-school fi nishing methods. Roller burnishing has shown promise in addressing these issues. It can smooth out rough surfaces and improve dimensional accuracy [2]. Minimum quantity lubrication (MQL) is a lubrication method in which a small amount of lubricant is applied directly to the cutting zone. This method reduces friction, extends tool life, and produces a smoother surface. All this is achieved without the environmental and fi nancial problems that come with using large quantities of lubricant. Recent studies have shown good results when combining MQL with various machining processes, including turning and milling [3–6]. Kurkute and Chavan [7] optimized surface roughness and microhardness during roller burnishing of Al63400 alloy. In their study, feed was considered as a signifi cant parameter aff ecting surface roughness. Patel and Brahmbhatt [8] found that spindle speed and burnishing depth were the most important parameters for improving microhardness by 28 % compared to pre-machined surfaces. A group of researchers performed roller burnishing by varying the process parameters such as feed, depth of cut, cutting speed, and number of passes. Most of the studies designed the experiments using the central composite design of response surface methodology. Some studies considered the cutting speed as the dominant parameter aff ecting the surface roughness, and some studies found that the feed signifi cantly aff ected the surface roughness. Some studies reported that the depth of cut signifi cantly aff ected the surface roughness, and the cutting speed and number of passes signifi cantly aff ected the microhardness. Some studies reported the interaction eff ect of burnishing force and number of passes on the surface roughness. The cutting speed, feed, and number of passes signifi cantly aff ected the surface roughness and microhardness. However, it can be noted that the signifi cance of process parameters aff ecting the process response can be assessed as varying depending on the process parameters, the workpiece material and the cooling conditions. Prasad and John [9] studied the roller burnishing process on Mg-SiC composite material. In their study, experiments were conducted by varying the cutting speed, feed, force, and number of passes. The authors observed a decrease in surface roughness at a speed of 171 rpm, a feed of 0.18 mm/rev, a force of 21 N, and three passes. The group of researchers observed changes in the surface and metallurgical textures due to the development of high contact stresses and an increase in plastic deformation of the surface layer of the component during roller burnishing [10]. The study showed an improvement in surface fi nish at lower burnishing speed and higher depth of penetration [11]. Okada et al. [12] analyzed the performance of roller burnishing under minimum quantity lubrication. In their study, an increase in workpiece hardness by 126–323 HV was observed. A group of researchers performed roller burnishing using diff erent coolingmethods such as cryogenic burnishing and using kerosene as a coolant. The group observed an increase in surface hardness and the surface fi nish when burnishing under MQL conditions and using kerosene as a cutting fl uid [13–15]. The group evaluated the surface integrity by varying parameters such as speed, feed, number of passes, and cooling conditions, namely fl ood cooling, MQL, cryogenic cooling, and hybrid cooling. The results showed that the use of cryogenic cooling increased the strength of the material, while the use of hybrid coolant decreased the surface roughness. It was noted that microhardness depends to a small extent on the type of cooling conditions. From the reviewed literature, it is evident that the roller burnishing process is eff ective in improving the overall surface quality and hardness of the workpiece. In addition, roller burnishing is considered as an aff ordable method to improve the functionality and reliability of the machined parts by reducing the occurrence of surface defects such as scratches and cracks. Studies have shown that the use of MQL in roller burnishing provides the opportunity to further improve the process by improving lubrication and reducing
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