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Handle fragile parts

Aug 22,2022

Pull-outs are a common type of workpiece when working with fragile parts. If the pull-out is not cast during cutting or mounting, this is usually the result of over-grinding or polishing and can be avoided by using simultaneous rotation in all grinding and polishing steps, except for the **polishing step, and making sure the polishing cloth is relatively soft when used.

Stripping may be found in cast iron, components, coatings and composites, although these may be incorrectly identified as cavities in the material.

Foreign inclusions may occur when the pressure is too high or when preparing very soft materials with very hard abrasives (e.g. diamond). This can cause abrasive particles to become embedded in the surface of the sample - a problem often encountered when working with composites with soft and hard phase compositions, or when working with materials of different hardnesses on a single polishing cloth.

Many steps can be taken to help avoid foreign body inclusions, including using similar materials on one polishing cloth, selecting the most appropriate abrasive for the sample material, or storing the cloth in a dust-free environment.

When materials with different phases are polished over a long period of time, relief often occurs. As a result, the harder phases will stand out more than the softer ones. This artifact is usually the result of over-polishing and can be minimized by using an abrasive disc with a hard carrier to make the sample as flat as possible. Preparation time should be kept to a minimum, especially in the **steps**. The use of polishing cloths with low elasticity is also recommended.

During manual preparation, non-metallic inclusions, porosity and hard phases in the soft matrix remain constant in one grinding and polishing direction, * where comet tails will be found. Comet tails are a problem when working with large samples of material, but can be avoided by moving the sample in a way that is not **oriented.

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Aug 22,2022