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--------------------------------------Scott Workman B.S.MSC Metallurgical Engineer

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Welcome to Metallurgical Welcome to Metallurgical InspectionInspectionSectioning and polishing of SamplesYou will Learn the correct Techniques to

become advanced in your Inspection Duties.

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Agenda Agenda

Sectioning BasicsMounting of SamplesThe Rough GrindFinal PolishResults

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VocabularyVocabulary

Section – to cut parallel to root or valley. Mount – using a plastic resin to hold part that was

sectioned. Rough Grind – to use any sanding disc under 120

grit. Polish – to remove scratches on sample and excess

mounting resin around the sample; to give a high sheen on sample for testing so as to have uniformity in results for all inspectors.

Results – The final product of our hard work is seen in the Quality and workmanship of our mounted, polished sample.

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Overview Goal Overview Goal Our Goal is to have all samples identical

when we section the parts, mount sample’s and polish. When we complete our goals we will have a uniformity that our customer requires ,as well as equivalent results that show trends, Metallurgical problems ECT.

Think

Goals

TRAIN

Skill motivate

Achieve

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The Sectioning of PartsThe Sectioning of PartsThere are many ways to section a part such as the Fracture,

Shearing, Sawing and Abrasive Cutting. At MSC we use the Abrasive Cutting method. This method is the most widely used in the Heat Treat Industry for sectioning materials for microscopic examination. The abrasive wheels we use are the most economical,fast and accurate .The sample to be sectioned must be kept cool during this process. This is why we add a cutting fluid rust inhibitor to our water inside of the saw at a 10 to 1 ratio. The speed that the blade turns using our blades will not burn the part, it is the force applied with not enough coolant reaching the sample.To much force applied will also cause blade flex as seen after mounting sample with resin fill into interior of sample. To much force will also break the blades.

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Mounting of SamplesMounting of Samples

The Mounting of a sample is necessary in our preparation of samples for a effective case traverse and metallographic review. After sectioning the part parallel to the root so the accuracy of hardness HV and traverse effective case is accurate. At MSC we use a thermosetting plastic resin with wood flour filler called Bakelite.The mounting press we use has preset temperature, time and pressure.The associate should use on average two table spoons of bakelite with each mount.

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The Grind and PolishThe Grind and Polish

The grind is used to dress the edge of the mount and take off any imperfections,excess bakelite on rear or the face of mount.{NOTE: use the least amount of pressure or force to mount as in the depth of scratches and mount staying parallel for testing is critical }The next step is to use sanding disc to remove scratches at 180 degree intervals in between sanding disc or opposite direction of the visual scratch.The sanding procedure is completed on 4000 grit paper.The sheen of no scratches and edge retention of sample is imperatively achieved using a slurry of alumina and water mixed and applied to a soft billiard type cloth. The mount is then polished with a lite amount of force to achieve the sheen required.

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Where to Get More InformationWhere to Get More Information

You may obtain a further understanding of this process in the ASM hand book Volume nine or a Course from ASM.

You may also contact the Metallurgical Engineer at MSC for a hands on approach to learning technique that is very important with mastering these needed skills.