Calibration of Coating Thickness Standard

[WilliamM]

Hello all!

I need to calibrate a coating thickness standard. Our current procedure calls for using a certified thickness standard and a coating thickness gage, transferring the standard to the gage, and then measuring the UUT. I am looking to try to change this procedure. I haven't been able to find any decent information on the internet, and I have not been able to find any fourm posts here that deal with coating thickness standard calibration. Does anyone know of a good procedure or document standard that could assist me in this endeavor? Any advice is greatly appreciated.

 

[Stijloor]

A Quick Bump!

Can someone help?

Thank you very much!!

 

[sowmya]

I have attached ours. let me know if it is useful.

if you have improved one, pl. share

 

[andygr]

The standard is the easy part. All you are doing is establishing a defined "air gap". Films are the most common items used to create this gap and can be measured using a micrometer. Use an anvil face the same size as your probe if at all possible since this will account for the same variations in the surface roughness of the substrate. Make sure you add a visual check for the shims since over time they get damaged and in the area of wrinkles, dents and such that thickness of the shim is no longer what it started out to be. I would go with "when in doubt throw it out" approach for visible damage.
The hard part is making sure that your substrate is "the same" under the shim you are using to calibrate. This applies to the part if you are calibrating directly on the part or a test piece used to simulate the part. Changes in conductivity, surface roughness and such can result in differing readings when in fact you might have exactly the same coating thickness. I would recommend that as part of the calibration performed to measure the part you also verify that the "zero" reading is verified.

 

[jawadali29]

Dear Mr. William,

I am facing the same issue as i have purchased coating thickness standards from elcometer but i was not able to find any 17025 accredited laboratory to calibrate these standards. Can you tell me what you have done finally for these standards?

 

[WilliamM]

We eventually had to settle for a rough comparison between our certified coating thickness standards and the UUT. We used a coating thickness gage as a transfer. I wasn't comfortable with it at all, but it was what our customer wanted. We had the same issue with Defelsko, as they would no longer certify coating thickness standards. The only other laboratory that we found that would certify the standards is in Australia, and I am not certain as to their accreditation status. I would agree with andygr and purchase a new coating thickness standard. That might aleviate headache in the future.