Research On Deterioration And Improvement Of CMP Polishing Pad For Cemented Carbide Inserts

Cemented carbide is often used as cutting tool materials for automotive,aviation,aerospace,and other fields due to its excellent hardness,toughness,and wear resistance.Using chemical mechanical polishing(CMP)to process cemented carbide tools can obtain a low/no damage surface and improve the cutting performance of the tool.As an important consumable for chemical mechanical polishing of cemented carbide tools,the polishing pad is a key factor affecting processing quality and cost.This research has carried out an in-depth study on the deterioration of the polishing pad,the groove of the polishing pad,and the dressing of the polishing pad during the CMP process of the tungsten-cobalt cemented carbide inserts.The main research contents are as follows:(1)The deterioration law of the polishing pad in the CMP of cemented carbide inserts is revealed.The main process parameters of cemented carbide inserts CMP are optimized through single-factor experiments,and the polishing pad degradation experimental research was carried out based on the optimized process parameter values.The main conclusions are as follows: The deterioration of the polishing pad during the CMP process is mainly manifested as surface cracking damage,pore siltation,and corrosion oxidation,among which the surface cracking damage is the main factor.The polishing pad deteriorated severely after CMP polishing for 60 minutes,resulting in a decrease in material removal rate and surface roughness level.At the same time,the hardness of the polishing pad decreases during the CMP process and is uneven.(2)The research on the groove of the polishing pad of cemented carbide inserts CMP has been carried out.According to the CMP operating conditions of the cemented carbide inserts,the composite groove pattern is designed.Based on the theory of computational fluid dynamics,a simulation analysis was carried out on compound groove shape,depth,width,and spacing.The simulation results determined that the optimal size elements are rectangular grooves,groove depth: 1mm,groove width: 2mm,and groove spacing: 4mm.The polishing pad groove was prepared by laser processing and the CMP experiment was carried out.The experiment result shows that: Compared with ordinary polishing pads,grooved polishing pads maintain better surface morphology before 60 minutes during the CMP process,but the deterioration is more obvious after 80 minutes,and the chemical corrosion of the polishing pad surface is more serious.The grooved polishing pad increases the CMP material removal rate by an average of20.05%,and the surface roughness decreases by an average of 40.6%.(3)A diamond dressing disc was developed,and an experimental study of online and offline trimming of cemented carbide inserts CMP polishing pads was carried out.Select the offline trimming pressure,speed,time,and temperature to conduct a four-factor four-level orthogonal experiment.The experimental results show: The dressing pressure,dressing speed,and dressing time have a significant influence on the material removal rate.The material removal rate is the largest when the dressing pressure is 21.3N,the dressing speed is 40 rpm,the dressing time is 30 min,and the dressing temperature is 40?;The dressing pressure and dressing time have a significant effect on the surface roughness.When the dressing pressure is21.3N,the dressing speed is 60 rpm,the dressing time is 30 min,and the dressing temperature is60?,the surface roughness is the smallest;The dressing pressure was selected for online dressing single factor experiment,the results show that: As the dressing pressure increases,the performance of the polishing pad first increases and then decreases.When the online dressing pressure is 21.3N,the dressing effect is the best,and the CMP comprehensive level is the highest.When the online dressing pressure takes different values,the surface morphology of the CMP inserts behaves well.