Factors Influencing Self-conditioning Of Hydrophilic Fixed Abrasive Lapping And Polishing Pad

Due to the characteristics of free abrasive, such as the distribution of the abrasive randomness and low utilization rate of abrasive, several inherent drawbacks of traditional polishing technology cannot be overcame. Fixed abrasive lapping and polishing technology has attracted more and more researchers. Self-conditioning is one of the most important properties of hydrophilic fixed-abrasive lapping pad, exerts great impact on lapping efficiency and surface quality of lapped work-piece. In this paper, both the theoretical analysis and practical testing were used to investigate main factors and implementation mechanism of its self-reconditioning. The main completed work as follows:1.Contact mechanics model of fixed abrasive lapping pad(FAP) and workpiece was established. The distribution of lapping load on fixed abrasive lapping pad was studied. The results showed that by the hardness and brittleness of workpiece material increasing, the contact area of the workpiece and the lapping pad gets smaller with the same load, but the force of single abrasive particle on pad surface is larger and the quality of the workpiece surface obtained also get worse. Based on the analysis of lapping force of single abrasive particle in the lapping process, expounds the shedding process of diamond abrasive on lapping pad surface.2.Relationship between the characteristics of hydrophilic fixed-abrasive lapping pad(FAP) and its machining performance has been studied. Six kinds of lapping pad were prepared in which three matrix resins acts as binder adding silicon carbide particles and pore-forming agent to modify its characteristic. The results show that matrix hardness and swelling rate, slurry wear rate are in reverse. Matrix hardness exerts important impact on the lapping efficiency and the average surface roughness(Ra). With the increase of the matrix hardness, the material removal rate increases, while the surface roughness deteriorates. The addition of silicon carbide particles is helpful to stabilize the surface quality of the workpiece being lapped. The pore-forming agent could help to stabilize its material removal rate(MRR) and promote the realization of its self-conditioning process.3.Retention rate of material removal rate was chosen as the index to assess the self-conditioning ability of FAP. The orthogonal experiment method was applied to explore the effect of materials, platen speed, applied load and slurry flow rate on the successive lapping performance of FAP. The contact mode of lapping pad-workpiece was analyzed using contact mechanics. The results indicate that a larger friability and a heavier load are helpful to the realization of self-conditioning of FAP. This research provides a reference for the determination of processing parameters and the application of FAP.4.In order to investigate implementation mechanism of its self-reconditioning, PHL-350 high speed lapping and polishing machine was used for an experiment on K9 glass wafer. The influence of applied load and pore on the self-conditioning performance of FAP was studied. Results show that the self-conditioning performance of FAP improves a lot with a rise of applied pressure. The slurry wear rate almost increases by 7 times with the addition of pore forming additive, improving the stability of material removal rate. So, increasing applied pressure and weakening matrix benefit the self-conditioning process of FAP.