Measuring Hard Chrome Plating Thickness

A. Good magnetic thickness testers are non destructive and excellent for checking hard chrome on steel.

It is accurate to about .0001, that should be good enough for almost any application.

A. A relatively cheap hand held magnetic instrument normally measures no better than a tenth, plus or minus a tenth. It does not sound like the accuracy that you desire. Fischer makes a lab unit that you can calibrate on a part or a scrap part section that will read to hundredths, plus or minus a few. I think that a few others also make one. There may be new hand held ones with that accuracy, but I have not seen one.

A. We have tried many types of electronic thickness measuring devices without much luck, especially at these small thicknesses. The one that did the best was one from Kett. The units are loaded with all kinds of statistical information, except they fail in repeatability and absolute accuracy. The best method we have found was the old stand-by: The Magna-Gage, The hand held Biddle gage also does a fine job for the money. The absolute method which we use is before and after micrometer measuring. We take at least ten measurements and calculate the mean and standard deviation. This method yields a very good absolute measurement and an idea of the variability before and after plate. Obviously this is not feasible with thousands of parts, but lends itself quite well to many Hard Chrome applications.

A. In regards to your letter I believe the test equipment you're looking for is called a DELTASCOPE MP2, made by Fischer Technology.

It's very accurate, easy to use and like the previous response said Fischer makes it.

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Ed. note-- James, Tim, Erin: To the extent possible please try to restrict the discussion to technologies rather than brands (why?). We can't count the threads that raced to the bottom once people started debating brands, which immediately introduces vested interests :-)

? Hi, Vijay. Just to be clear, the coating on the molds used in your hobby is hard chrome plating? Why can't you inspect them and do thickness testing with them cold? Thanks.

Regards,

A. You can buy Electrophysik coating thickness gauge, German make distributed in India; or Opus makes instrument

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Ed. note-- Sudheer: To the extent possible please try to restrict the discussion to technologies rather than brands (why?). We can't count the threads that raced to the bottom once people started debating brands, which immediately introduces vested interests :-)

A. Hi BN. You haven't given us the background/situation yet, such as whether there is a contract dispute -- in which case, as you yourself say, a microscopic test may be the referee method. But this is a destructive test that can't be used on your actual parts, only on samples.

Hard chrome plating is often thick, so a common approach for round parts is to measure the diameter (and possibly roundness) before plating and then again after plating to determine the thickness.

Regards,

 Hi Amrit. Surely as an engine manufacturer it seems very unlikely that you haven't tried something by now :-)

People tend to be shy about making suggestions, when a situation like yours suggests that the response to their effort is very likely to be: "we tried that and weren't happy with it" :-)

Please try to give us a bit of background regarding what you've tried, what you thought of it, etc. Thanks!

Regards,