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Keeping powder coat paint out of threaded holes to prevent tapping after paint

 

Although we use plugs to plug our threaded holes, we continue to have to re-tap holes in final assembly. I need to know if there is a product on the market to prevent this from happening.

Thank you,

Bob Gladfelter
Powder Coating - Hanover, Pennsylvania
June 9, 2009

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First of two simultaneous responses --

Silicone pull plugs are excellent if you can use pull plugs. Some companies use a plug that you can insert with a tool that stretches it for insertion and then swells as it unshrinks from the long way.
Check out the company on the banner to see if they can help.

James Watts
- Navarre, Florida
June 12, 2009

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Second of two simultaneous responses --

Pesky powder just gets into everything. Standard plugs do a good job, and your problem is not uncommon by any means. Most of the major masking suppliers that support the powder coating industry will custom make plugs, Shercon and Echo come to mind. Maybe you can look at the Powder Coat Institute website to find an extensive list of suppliers. Custom plugs can be cheaper when compared to added labor cost of tapping after paint.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
June 12, 2009

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You weren't specific about what kind of hole you're masking.

For "blind" holes, several masking vendors carry "top thread" type plugs that have a flange on them to mask off threaded holes more completely than standard tapered plugs.

For a "through" hole, if the part is thick enough, two top thread plugs can usually be used. For welded nuts, there are specialty plugs to mask these as well, offered by a couple masking vendors. One style masks both sides of the nut; another just has a flange on the end of a pull-plug style mask, to mask one end of the nut. A couple vendors even offer two-piece masking options that have very large flange surfaces.

Custom options very likely can be designed if your part is very large and/or doesn't not match up to standard sized parts.

Check with several masking vendors, be specific about what you're masking, and ask for their suggestions. You'll likely find some very good options to consider.

Hope that helps.

David Fuller
- Monee, Illinois
June 15, 2009

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