International Journal of Abrasive Technology (3 papers in press)
High-speed high-efficient grinding of CMCs with structured grinding wheels
by Bahman Azarhoushang, Mohammadali Kadivar, Robert Bösinger, Sergey Shamray, Ali Zahedi, Amir Daneshi
Abstract: Ceramic Matrix Composites (CMCs) are counted as new materials which are widely applied in various engineering and technological fields owing to their superior properties. In spite of their remarkable properties, their implantation is limited due to their high machining costs as a result of high grinding forces and tool wear. To overcome mentioned problems, modified grinding wheels, one macro-structured by segmenting and another micro-structured (half lasered structured and half non-structured) were used in this study. The grinding tests were carried out at different material removal rates and cutting speeds. The grinding forces, generated surface roughness, and induced residual stress by means of grinding with the structured and non-structured wheels were compared. Reduction in the static cutting edges via wheel structuring resulted in a better performance of the grinding wheel through the reduction of rubbing and ploughing regimes. The grinding forces were respectively 30% and 20% lower in the case of segmented wheel and laser-structured wheel in comparison with the conventional grinding. In addition, the tensile residual stress can be reduced as a negative output of the grinding process via structuring. Moreover, a high-speed high-efficient grinding of CMCs without presence of surface damage was achieved by optimizing the process parameters. The material removal rate can be elevated without changing the grinding forces with application of the structured wheel.
Keywords: High speed high efficiency grinding; CMCs; Segmented wheel; laser-structure.
An experimental investigation on precision machining mechanism of carbon fiber reinforced polymer
by Xiaojiang Cai, Ruhao Zhou, Lifeng Shen, Hongliang Tang, Qinglong An
Abstract: With the rapid development of carbon fiber reinforced polymers (CFRP) as main aerospace structural materials, it is necessary to manufacture CFRP structural components for high dimensional accuracy by means of precision machining. In this paper, orthogonal cutting was used to investigate machining process and surface quality of CFRP materials for precision machining An intensive discussion was given about fiber orientation and cutting parameter range when machining CFRP for high accuracy application and optimized cutting method, including cutting speed, cutting depth, edge radius, fiber orientation, was obtained to reduce cutting force and surface roughness and get smooth surface topography. The cutting speed over 200m/min and small cutting depth slightly large than edge radius were advisable, the fiber direction 0~45
Keywords: carbon fiber reinforced polymers (CFRP); precision machining; cutting force; cutting speed; cutting depth; surface roughness; surface topography.
Research on surface integrity in graphene nanofluid MQL milling of TC21 alloy
by Ming Li, Tianbiao Yu, Hongyu Li, Lin Yang, Jiashun Shi, Wanshan Wang
Abstract: As a new type of damage-tolerance titanium alloy, TC21 alloy is widely used in aerospace. However, TC21 is a difficult-to-machine material owing to its low thermal conductivity, high chemical activity and low elasticity modulus. In this work, Minimum Quantity Lubrication (MQL) with graphene nanofluid was adopted in TC21 milling. In order to evaluate the effects of graphene nanoparticle on the surface integrity, a series of milling experiments were performed under the dry, gas, pure MQL and graphene nanofluid MQL condition respectively. Results showed that the graphene additive was effective for improving the surface integrity. Overall, the results could be explained that graphene additive could enhance the cooling and lubrication performances of the oil film formed in cutting zone. The findings of this work are expected to give a feasibility and some experimental basis for the application of the graphene additive in MQL milling.
Keywords: graphene nanofluid; MQL milling; surface integrity; TC21.