Effect of diamond Superfinishing on the Surface Roughness of Antifriction Composite Parts Made From Silumine Waste for Post-Printing Equipment

The article presents the results of studies on the influence of fine superfinishing modes with synthetic diamond bars on the formation of the roughness parameter Ra of the surfaces of samples made of new antifriction composites based on industrial grinding waste silumin — aluminum alloys AK7, AK12M2, AK21M2.5N2.5, which are intended to equip post-printing equipment. The influence of diamond bars’ grain size, type of diamond grain material, tool bonding, and basic cutting modes on the roughness parameters Ra of the machining surfaces of silumin composites for post-press machine parts was determined. The superfinishing was performed on a precision superfinishing machine FR-250 manufactured by Foster (USA), using a lubricant and coolant. For superfinishing, diamond bars based on synthetic diamond (SD) micropowders with a grain size of 40, 28, 20, 10, 7, and 3 μm were used. Metal bonds M2-01 and M2-08, ceramic bonds C3-01 and CK4, and organic bonds B2-01 and B2-07 were used as bonds. It was found that with a decrease in the granularity of superfinishing diamond bars (3–40 μm), the roughness parameters Ra of the machined surface decreases. It has been shown that with an increase in the workpiece rotation speed Vw and the speed of longitudinal-reverse displacements Vl.r. of the superfinishing diamond bar along the sample axis, the roughness of the machining surface becomes worse (the Ra parameter increases by 10–15 %). This fact is associated with the cutting modes intensification in accordance with the general principles of the abrasive machining theory. The minimum surface’s roughness Ra parameters of the machining zone can be obtained by using fine-grained synthetic diamonds (SD) with a grain size of 3–7 µm on an organic bond and by applying the following technological modes of cutting during diamond superfinishing: workpiece rotation speed Vw = 80–120 m/min; speed of longitudinal and reverse movements of the bar Vl. r. = 0.5–1.0 m/min; specific pressure of the bars q0 = 0.9–1.1 MPa, vibrations amplitude of the bars A = 3.0–5.0 mm; intensive use of lubricant and coolant. This ensures that the quality requirements for the surfaces of friction parts of post-printing machines are satisfied. The research results on ultrafine diamond superfinishing of new composites types based on silumins grinding waste for antifriction parts can significantly improve the stability and reliability of post-printing equipment’ friction units due to the possibility of obtaining composite parts’ high surface roughness parameters.