A Nice Paint job

by Matthew Moore on 12th September 2006

Project Background

An electric motor manufacturer’s foundry was producing castings, the majority of which required primer painting prior to subsequent machining and assembly operations. Departmental inspection procedures failed to stop primer paint rejects being passed on resulting in major dissatisfaction with the foundry’s performance.
A new water based primer painting process was being installed in the foundry but existing process controls were unlikely to prevent reject levels similar to those experienced on the current process.

Problem

Casting defects at the primer painting stage were running at a recorded average of 4.95% recorded as costing €42,000 per annum. Poor reject tracking meant up to 10% rejects were actually costing almost €80,000. Paint was settling in containers, conveyor stoppages were causing ‘tide marks’, air was appearing in the paint due to dirty filters, paint viscosities were incorrect due to poor methods of mixing, paint was blistering from water contamination due to incorrect hanging methods, some castings had paint blobs due to poor hook conditions, and most significantly, there was poor process capability resulting from lack of defined paint specifications.

Solutions

A six sigma project was set up. After developing a proper measurement system and completing rigorous failure modes and effects analyses, paint specifications were determined and issued to suppliers. Paint containers were inverted every 0.5hours. A new castings hanging method was determined to include standard operating procedures & visual controls. An improved Total preventive maintenance system was implemented for filter and hook cleaning. A new procedure was introduced to control paint viscosities. New shift handover methods were introduced linked to control of breaks to reduce conveyor stoppages.