SUNConferences, 27th Annual Conference of the SA Institute for Industrial Engineering

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FAILURE ANALYSIS OF LOCOMOTIVE ALTERNATORS USING THE SIX SIGMA METHODOLOGY
Amos Mekwa, Mukondeleli Grace Kanakana, Khumbulani Mpofu

Last modified: 2016-09-16

Abstract


The series 6E diesel electric locomotives use an alternator to produce power to traction motors that are mounted to bogies to drive the locomotive. Company XYZ is the largest repairer of the locomotive alternators which refurbishes an average of 675 locomotive alternators per annum. Locomotives are coupled with wagons to supply commodities in South Africa. Company XYZ faced high failure rates due to locomotive alternators defects. These defects led to service issues and revenue losses. Therefore, the company embarked on a project to investigate strategic initiatives to reduce failure rate. Six Sigma DMAIC methodology was identified as an initiative that focused on improving quality of locomotive alternator by reducing failure rate. The current Six Sigma level was at 3.8 sigma with defect per million (DPMO) of 11481 at 675 units annually. Of 675 refurbished locomotive alternators produced annually, 18% had failure rate. Through implementation of DMAIC methodology, insulation on an armature was the highest type of failure. A resolution was proposed that each locomotive alternator that had operated more than 12 months in-service must undergo complete armature insulation. This proposal reduced failure rate to 6%, thus yielding improved Sigma level of 4.2 with a DPMO of 3457 at 675 units.


Keywords


Six Sigma, Product Quality, Variation, Product Defects