MRR Sigma Reduction in Fine Lapping Process of Slider Fabrication

Abstract

This article intends to reduce variation of MRR (Magneto-Resistive Resistance) in Fine LappingProcess of Slider Fabrication. In the case study, it was found that the electrical yield of slider fabricationwas 91.51%, which does not meet target at 93% of total inspected parts, and the overall yield of sliderfabrication was 84.65% of total produced parts. From the study, the major problem was çout-of-specificationMRRé, which was mainly contributed from the fine lapping process. The process capability index(Cpk) was 0.85, which indicated that the process had lapping control problem. Next step, the theories ofresistance and real lapping process were studied. The factors that impact variation between bar of MRRwere defined by cause and effect diagram and experimental design. The several experiments revealed thatbar pressing method significantly effects the variation between bar, because the uniform load method canreduce bar twist before lapping. After implementing the new bar pressing method, electrical yield is increasedto 91.86% of the total number of inspected parts. The Cpk index is increased to 1.26. Finally, overallyield is increased to 84.81% of the total number of produced parts.

Keywords : Slider fabrication / Variation reduction / MRR / Lapping process