Research On Subsurface Damage In Fixed Abrasive Lapping Based On Single Abrasive Particle

The subsurface damage of brittle materials in lapping process will directly affect the performance and service life,and even lead to irreparable results.Studying on the control and mechanism of subsurface damage in the lapping process is conducive to optimizing the processing technology,improve processing efficiency and rapidly achieving the purpose of low / non subsurface damage.The fixed abrasive lapping is widely used in ultra precision machining of brittle materials because of its strong controllability,clean and environmental protection and good tanning effect.From a micro point of view,the grinding process of the fixed abrasive can be abstracted and simplified into a process of pressing and engraving the material by a single abrasive particle.At the same time,the single abrasive particle has good controllability,therefore,the study of the effect of this single abrasive particle has become an important means to study the complex grinding mechanism.In this paper,the subsurface damage produced during the grinding process of a brittle material is studied.On the basis of the compression and characterization experiments of single abrasive particle,the optimum depth of cutting with a single abrasive grain depth model is obtained by using the side cycle polishing etching method.Then the grinding pad is designed to control the subsurface damage of brittle materials.The main research results of this paper include the following aspects:(1)The surface / subsurface crack morphology of the hard and brittle materials by the single abrasive particle was investigated.The side cycle polishing etching method was also introduced and applied to this study.The mechanism of crack propagation in hard and brittle materials was discussed during the static loading test of a single abrasive.The empirical relationship between the load and the depth of crack propagation under static loading was obtained,and the empirical relationship between the indentation depth and the crack growth was also discussed.In the dynamic erasing experiment,while getting the critical depth of the brittle-ductile transition,it was found that the ratio of the penetration crack had been relatively higher in the semi-ductile removal domain which was near the critical depth.Not only could it meet the requirements of the low subsurface damage,but also have higher removal efficiency and all these had been verified by the constant load scratch test.(2)The surface / subsurface crack morphology of the soft and brittle material with the single abrasive particle was investigated.The mechanism of crack propagation in soft brittle materials was discussed in a single abrasive loading test.The empirical relationship between loading load and crack propagation under static loading was obtained,and the empirical relationship between the indentation depth and the crack growth was also discussed.In the dynamic erasing experiment,it was found that even when the surface is in plastic removal,the subsurface may produce cracks.To address this issue,the cutting depth which could avoid producing cracks was gained by the experiment.(3)The subsurface damage of brittle materials was well controlled in the fixed abrasive lapping process.According to the characteristics and processing requirements of brittle materials,a single abrasive cutting depth model is selected.Combined with the best cutting depth obtained by the side cycle polishing etching method,the fixed abrasive pad(FAP)is designed and made to achieve subsurface damage control of fixed abrasive and brittle materials.