8/7/2019 Laminates Company - Epoxy Spot Defects

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The Problem

A laminates company was experiencing a largeincrease in the number of epoxy spots left onthe finished product after the manufacturingprocess. This problem had started several monthsearlier when the company changed its customerrequirements. The epoxy spot defects wereincreasing scrap and manufacturing overhead

costs, and reducing on-time delivery rates dueto rework, remake and inspection activities.

The company assembled a problem-solvingteam to investigate the situation and launch aproject with the goal of reducing the epoxy spotdefect rate from 1.5 percent to 0.35 percent.The team estimated this shift would cut materialcosts by approximately $100,000 annual ly.

The Solution

The project team started investigating wherethe spots were coming from by looking at all thepossible reasons for the increase in spots. They

quickly ruled out variations in the inspectionprocess as a major cause of the problem sinceinspectors merely counted and documented thenumber of epoxy spots. So, instead of focusingon inspector variation with a Gage R&R study,the team used process maps, affinity diagramsand fault tree analysis to determine the greatestsources of the epoxy spots.

The team identified two main sources ofincreased epoxy spots: operator handling ofmaterials and “random factors.” The latterincluded many variables — trays, conveyors,even the air itself. The team felt that pursuing

these “random factors” would require a long,comprehensive investigation that may not leadto the level of change it desired. Therefore,the team chose instead to dig deeper into theoperator handling procedures to locate potentialareas for improvement.

The team’s research suggested that handlingprepreg (a raw material used in the laminateprocess) caused some operators to collect epoxydust, which was then sometimes accidentallytransferred to the f inished product. Teammembers tested this theory by running a two-

proportion hypothesis test. The results indicatedthat operators with clean hands produced 40to 80 percent better yields than those whotouched the prepreg material before handling thelaminate.

Therefore, the team looked at ways ofstandardizing the hand-washing process forall operators who came in contact with theprepreg material. Their research showed thatin the current state, the operators who handledprepreg were in the habit of cleaning their handsafter every instance. However, operators at onelocation cleaned their hands with alcohol-soakedrags while those at another plant used only taccloth.

The team ran hypothesis tests to compare thetwo methods. Tests showed that the alcohol-soaked rag cleaning process yielded 40-50percent better results than the tac cloth method.

In addition, the tests found that one pair ofoperators yielded consistently better resultsthan all the others, regardless of the method ofcleaning they used.

Digging a little deeper, the research teamshowed that these two “cleanest” operatorsalways washed their hands thoroughly, wiping twoor three times after touching the prepreg.

To see if it was the operators or the processthat was causing the improvement, the projectteam conducted a Design of Experiments with adifferent pair of operators who typically cleanedtheir hands with only a single wipe (like mostoperators were doing). Test results showed thetriple wipe yielded 40-80 percent fewer epoxyspots than the single wipe.

The Results

The team proposed that operators standardizeon a new hand cleaning method using taccloth and that they wipe their hands morethoroughly including behind the fingers andinside the thumbs. The team also provideddetailed instructions on the new proceduresand established methods to track the operators’

CASE STUDY | Reducing Epoxy Spot Defects

 A laminates company reduces number of epoxy spots on nal product

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Problem Solved.

Summary

Industry

Manufacturing

Business Problem

High rate of defects due to epoxyspots

Methodology

Six Sigma - DMAIC

Solution

Reduce defects by making

a change in operatorhandling procedure

Benefits/Results

$320,000 in annual savings

BMGI

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adherence to this new procedure. Since theimplementation of the new cleaning method,the company has experienced a 66 percentreduction in epoxy spot defects resultingin annual savings of more than $320,000 inmaterial and overhead.