Cutting Mechanism And Roughness Evaluation Of SiCp/Al Composites

SiCp/Al composites have a mature manufacturing process and its application gradually developes from military use to civil use.SiCp/Al composites with middle and high volume fraction have been increasingly applied in many fields due to its high specific stiffness,specific strength,good corrosion resistance and thermal conductivity.However,it is its good physical properties that cause the difficulties in the machining process,complex processing mechanism and the uncontrollable quality of surface.It also makes the extraction of roughness difficult.Therefore,it is necessary to research the cutting mechanism of this type of material and make an accurate roughness evaluation method of so that we can make a great guidance for the production and application.Based on these two aspects,some researches have carried on in this paper as the following:(1)A series of experiments have been taken with SiCp/Al with different aluminum substrate materials,particle size and volume fraction of SiC.We have analyzed the effect of aluminum substrate materials,enhanced particle size and volume ratios to cutting force.The chip microstructures have been observed to explore the SiCp/Al cutting mechanism with middle and high volumes fraction.(2)Making a tool wear experiment,we do research about the influence of al-matrix to tool wear.In view of the complexity of fluctuation of the cutting force of SiCp/Al material,we make a comparison of the effectiveness of the mean value,fractal dimension,characteristic parameters of power spectral and singularity parameters of cutting force on forecasting of the VC of tool wear,getting the reasonable prediction method of tool wear when cutting of SiCp/Al matrix material.We have found that the mean value of cutting force was the most effective parameter in prediction for tool wear because of its stability when time and frequency shift happened.(3)The machining surface of SiCp/Al composite materials contains of lots of bumps,potholes and defects,leading to the confusion of roughness and defect information and unreasonable evaluation of the machining surface.In order to extracting the roughness of SiCp/Al composite materials,a filtering method based on dual tree complex wavelet transform has been put forward of in this paper.The least squares method,Gaussian filtering method and the filtering method based on DT-CWT were adopted to extract the information of 3d surface roughness and evaluated from two aspects including of stability and the degree of influence by defects.The results show that filtering method based on dual tree complex wavelet transform has high stability and can distinguish surface roughness from defect information more effectively.Therefore,it is more suitable for the extract of the surface roughness of PMMC.Based on the comparison between the machining surface of SiCp/Al whose Al-matrix includes of 2024 and 6063 aluminum alloy by the filtering method base on DT-CWT,we find that the quality of 2024 aluminum matrix composite material surface is better than that of SiCp / 6063 al composite materials.