Surface preparation for Magnetic Particle Inspection

One of main things is that you want your workpiece clean. I've been amazed how many people try to check for cracking using mag inspection with parts covered with dirt, grease, oils, etc.

Also, avoid operations on the workpiece like peening, blasting, etc., as these can at times hide evidence of cracking. Gentle abrasive cleaning is usually OK, but heavy blast operations can compromise your work.

Remove any type of screw on/bolt on hardware as well.

I want to clarify something about cleaning operations before mag inspection. As I said in my previous post, gentle abrasive cleaning can be done.

Now, the key word is gentle. It is possible to lightly clean and prepare a surface using walnut shells, glass beading, or gentle sand blasting. However, violent blast methods can peen over surface cracking temporarily and make a workpiece appear to be crack free even when it is not.

This is why, and verified by long years of practical experience, that one needs to be careful using abrasive cleaning.

I will add that you should consider other methods of inspection to accompany mag inspection. A combination of methods can usually detect cracking throughout a workpiece. I refer to dyes, x-ray, ultrasonic, etc. Using mag inspection along with these methods is a reliable and prudent course of action.

While cleaning check the medium used for cleaning- especially for wet MPI- the surface should be wetted by the fluid - This is especially critical for water based suspensions - Preferable to clean the surface with detergent or other oil stripper.

Avoid clogging of possible defects

Ensure the Iron Suspension has sufficient contrast with the parent surface. Slight rust / other coatings does not affect the indication only affects the visiblity of it,

Normally sand blasted surface cleaning presents very good contrasting back ground for magnetic crack detection check. Magnetic crack detection is considered good method precisely because it can reveal by polarized line of iron particle even if the surface flaws are hidden. The results will even more spectacular with fluorescent magnetic particles with ultra violet light, is used.

Hi All

I was wondering what products i can use to clean metal prior to me electrostatic painting then.

Please! NO piggyback questions. If you want to ask a question, submit as a new thread.

Are you suffering from multiple personalities? Are you telling yourself not to ask another question? And where did you get your the rule book from? My rule book for CR4 says no UNRELATED piggyback questions. And my rule book says on page 32 that you would be required to make up some phony name before quoting the rules.

When I have had that process done, it has been on an automotive cylinder head. In all cases, the head was put in a hot tank washer. The washer sprays hot (180*) alkaline solution on the head as it rotates. The washer runs for about an hour to get everything hot, and clean. After this it is rinsed with water. I hope this helps.