Comparison of lapping performance between fixed agglomerated diamond pad and fixed single crystal diamond pad

The ability for self-conditioning is the most important characteristic of hydrophilic Fixed Abrasive (FA) pads using in lapping. The failure mode of diamond abrasives embedded in a FA pad greatly impacts its self-conditioning process. In this investigation, three types of FA pads were prepared. One was embedded with W50 single crystal diamond (SCD) abrasives, one was embedded with W10 SCD abrasives, and the other was embedded with agglomerated diamond (AD) abrasives. The lapping performance was tested on fused quartz workpieces. The pad wear mechanisms and the wear debris of the three pads was evaluated using Scanning Electron Microscopy (SEM). The FA pad embedded with AD exhibited a higher material removal rate and a lower arithmetic average surface roughness (Ra) of the lapped quartz than those embedded with SCD. Pad loading and flattening of the of abrasive grit are the main factors causing the failure of FA pad with SCD. Compared with FA pads with SCD, the rough surfaces of AD grains improves the holding force of pad matrix to them, which in turn leads to a more stable cutting depth of abrasive grain. Size analysis of the debris suggests that AD grains are inclined to micro-fracture rather than to wear flat or pull out. The micro-fracture phenomenon of AD in FA lapping process improves the material removal rate and lowers the average surface roughness of lapped workpieces. The adoption of AD grains was concluded to be important in improving the self-conditioning performance of FA pads.