Papers by Keyword: Semi-Fixed Abrasive Tool

Abstract: Abrasive machining is an important process for the manufacturing of advanced ceramics. The demand for advanced ceramics with better quality and higher efficiency presents tremendous challenges for abrasive tools in the advanced ceramics industry. The concept of semi-fixed abrasive machining with a newly developed semi-fixed abrasive tool (SFAT) as machining tool is put forward. This paper presents an experimental investigation for SFAT wear into course of machining single crystal silicon with SFAT. Process parameters (water flow, load and velocity) influencing the SFAT wear are analyzed. Influencing factor of SFAT wear in processing course has been clearly demonstrated.

Abstract: The semi-fixed abrasive tool (SFAT) is a new tool used in the ultra-precision machining. Based on the theory of particle flow code (PFC), the abrasive particle motion characteristics of SFAT are studied in SFAT processing which is divided to workpiece pressing progress and workpiece tangential moving progress. It is conclusion that the particles are fallen out the tool surface due to the fracture of bonds under the normal force of workpiece point in the workpiece pressing progress; the particles contacting the workpiece are moved on every hand while some particles fall out the surface at the edge of abrasive tool in the workpiece tangential moving progress, and the maximum value of binding agent holding force is computed.

Abstract: In order to reduce or eliminate the surface defects caused by abrasive grains and improve the efficiency of ultra-precision processing, the technique of semi-fixed machining has been proposed for machining advanced ceramics. A semi-fixed abrasive tool (SFAT) has been manufactured; it has performances of semi-fixed machining technique. This document demonstrates wear characteristics of SFAT through experiments of machining silicon wafer. It showed that wet status or dry status of SFAT has greatly influenced wear characteristics of SFAT. Wear characteristic of SFAT presented mostly blockage and little grain-off occurred in dry status; mostly grain-off and little blockage presented in wet status.

Abstract: ‘Trap’ effect of the newly developed semi-fixed abrasive tool (SFAT) plays key role in decreasing the surface damages of advanced ceramics caused by the undesirable large particles emerging in machining area. Influences of characteristics of the large particle, such as size, shape and concentration, on the ‘trap’ effect of SFAT are studied with Particle Flow Code (PFC) simulation and lapping experiments. A normalized normal force is defined to evaluate the ‘trap’ effect in PFC simulation, and surface roughness is taken as an indicator in lapping experiments. The results show that the change of surface roughness is according to the one of normalized normal force. Bigger normalized normal force is better for ‘trap’ effect and surface roughness. ‘Trap’ effect works well when the large particle is in small size, sharp shape, and low concentration. In this study, the followed characteristics of the large particle are good for ‘trap’ effect of SFAT made of 1000# SiC abrasive: size <17µm, corner angle < 60°, and concentration <18 particles per mm2.

Abstract: Semi-fixed abrasive tool is a new developed grinding wheel which can adjust abrasive grain near the workpiece-abrasive interface according to the situation of the hard and large grits, damaged surface layer generated by the scratch or crack could be decreased when using semi-fixed wheel. Porosity, one of the most important parameters to evaluate trap effect, was studied based on the analysis of uniform scratch and it’s effect on the polishing time, contact models between circle abrasive grain, line boundary and circle boundary were deduced to investigate the relations between engagement depth and the ratio of normal force to normal elastic stiffness. Theoretical research results show that semi-fixed grinding wheel should be conditioned after it’s compaction for the boundary between abrasive grain and line boundary is unstable, the contact status is stable for internal abrasive grain, predicted porosity value agree well with that measured in the experiment, the shear strength of semi-fixed abrasive tool can meet the demand of lapping and polishing processes.