Simulation and experimental study on micro-cutting silicon carbide crystal with single grain diamond

Abstract

ObjectivesThe hardness of silicon carbide is second only to those of diamond, cubic boron nitride, and boron carbide, making its processing very difficult. Compared with plastic metal materials, the brittle and hard nature of silicon carbide makes it prone to brittle fracture and edge fragmentation during processing, greatly affecting its superior performance. Therefore, it is crucial to carefully select appropriate cutting methods and establish reasonable cutting process conditions.MethodsThe finite element software Abaqus was used to establish a model of micro-cutting silicon carbide crystal with a diamond conical grain, and the selection range of micro-cutting depth and speed was determined by the pre-simulation model. Then, the main and secondary factors affecting the cutting force were analyzed, and the influence of a single cutting parameter on the cutting effect was studied. In addition, with the help of Hertzian contact stress, the influence of the loading force on the friction force, the morphology of the cutting edge, and the cutting depth was verified by the tip scratching experiment.Results(1) The cutting depth is a crucial factor that greatly impacts the quality of the cutting process. When the cutting depth is less than 1.50 μm, the removal of silicon carbide material primarily occurs through plastic removal. However, when the cutting depth exceeds 1.50 μm, cracks of varying lengths and pits of different sizes gradually form at the cutting edge of the workpiece. As the cutting depth increases, the length of cracks and the number of pits also increase. This type of removal is known as brittle removal. To ensure the integrity of the cutting edge and minimize damage to the silicon carbide workpiece, it is essential to control the cutting depth of the abrasive particles during stages I and III, keeping it below 1.50 μm. (2) Through variance and range analysis of the main cutting force, the relationship between the three factors and the magnitude of the main cutting force is V > W > U, meaning that cutting depth is the most important factor affecting cutting force. The optimal solution V1W1U2 and cutting parameters have been determined, namely a diamond abrasive cutting depth of 0.50 μm, a diamond abrasive cutting edge angle of 60°, and a cutting speed of 76 m/s. Cutting depth is the main factor affecting the magnitude of cutting force, while cutting speed and cutting edge angle are secondary factors. (3) As the cutting depth increases, the affected area surrounding the cut also expands, causing an increase in equivalent stress even in areas where the abrasive particles do not come into contact with the workpiece. This phenomenon is responsible for the development of cutting edge cracks and pits. Additionally, as the cutting depth increases, the main cutting force experiences greater fluctuations. To maintain cutting stability, it is important to control the cutting depth. In the high-speed cutting range of 60-106 m/s, the impact of cutting speed on cutting force is minimal. Therefore, increasing the cutting speed can be an effective method for improving cutting efficiency and ensuring high-quality cuts. For optimal results, a cutting depth of 0.50 μm and a cutting speed of 76 m/s are recommended. (4) The coefficient of friction is not only affected by the properties of the two materials in contact, but also by the depth of the diamond probe pressing into the workpiece. The greater the depth of pressing, the higher the coefficient of friction and the greater the frictional force. The surface of the microgrooves is clear and tidy, with relatively smooth edges. Under the same Hertz contact stress, the simulated depth values and experimental depth values show a consistent trend with the change in loading force.ConclusionsFinite element simulation has become a valuable tool for studying the interaction and removal of materials in the precision machining of crystal materials. The purpose of this article is to investigate the removal characteristics of silicon carbide and determine the optimal range of cutting parameters. The study analyzes cutting force, stress distribution, and removal mechanisms, and proposes effective methods for enhancing cutting efficiency. The findings of this research can contribute to improving the smoothness of the cutting edge and reducing subsurface damage to the workpiece. Furthermore, this research has significant implications for understanding the impact of process parameters on cutting accuracy and the removal mechanism of hard and brittle materials during cutting.

Keywords

• silicon carbide crystal
• diamond grain
• diamond tip
• cutting force
• cutting edge quality