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I have a sheet of metal that had grooves cut by laser in it; I need to analyze the depth of the grooves, and for that I think I will need to obtain a thin section slice of the metal and then put the sample under a microscope.

A microscope is not a problem to get, I have access to several. But my biggest issue here is how to obtain the section slice. Has anyone had experience doing something like that? I know that a microtome is used for obtaining very thin slices of biological samples, but not metals, I think. How do I slice the metal? Or is there perhaps a better, easier method of measuring the grooves' depth?

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  • $\begingroup$ If you take a section slice only, then how do you know it's representative of the mean or median groove shape? $\endgroup$ Jul 30 at 12:38
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The field you are looking for is called metallography, a subdiscipline of material science. There is even an own apprenticeship in some countries to become metallographer. There should also be extensive literature about this.

The short version of what you can do to get such metal slices is to cast it in resin (called mounting) and then grind and polish the cross-section of interest on special grinding disks with finer and finer grinding paper. This can go as far as polishing it in diamond suspension on a cloth.

The surface quality that is needed here depends on what you want to observe in the cross-section, for a depth analysis it probably does not need to be that polished.

This preparation of the specimen allows then to observe the cross-section under a microscope.

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  • $\begingroup$ If OP is near a university with a material testing lab, they have cutting and polishing machines to do precisely this, relatively quickly and easily. There may be non-destructive alternatives. $\endgroup$
    – Pete W
    Jul 30 at 11:10
  • $\begingroup$ Polish is very likely necessary as the grooves sound small. Cut with an abrasive wheel. It will be mounted in thermoset Bakelite because it is harder than resins and will give good edge retention. A university is likely to mess it up. Look for a lab at a heat-treat shop or a failure consultant. $\endgroup$ Jul 30 at 16:41
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    $\begingroup$ If the grooves are very small , iron powder may be added to the Bakelite for a harder mount = better edge retention. $\endgroup$ Jul 30 at 16:44
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There may be non-destructive options, like laser profilometers or even optical microscopy that can extract Z axis data. Check the back side too.

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