Efficient finishing/cleaning method for DOM tubing

[Ductmate]

I have a product that is made of 1 7/8" x 4" DOM carbon steel tubing with a machined bushing welded into one end. It has 3 8-32 threaded holes in it. I am looking for a way to efficiently remove the mill coating and paint from the DOM steel so that I can apply a phosphate (parkerized) finish.

I currently either sand blast them or use a wire wheel. The wire wheel sometimes misses spots, giving a poor finish, and both of them are labor intensive.

Does anyone have any suggestions such as a tumbler or vibratory bowl for this? Also, what kind of media do you recommend? I have a vibratory bowl currently loaded with crushed walnut for polishing, but that's not aggressive enough. I could make or acquire a rotary tumbler fairly easily.

Thanks,
Vince

 

[BillPSU]

Your description of the material is inconsistent with DOM. DOM is not normally not painted and the only coating is the drawing compound and/or oil. This sounds like a pipe product. What is the finished size of the tubing OD and ID?

 

[unclesyd]

All you will have to do is change your media and cycle in the vibratory bowel to achieve what you require. If you choose the vibratory bowel I would look at both wet and dry processes if you equipment will allow both. By using a wet process we have found that we can get a very good finish in one pass.
One thing to consider about using a tumbler is the possibility of dinging your parts. It will take a little effort on your part to get the loading, speed, and media down.

One of the more common cleaning methods is to use a hot alkaline cleaner to remove the drawing compounds.

 

[Ductmate]

BillPSU: The paint I'm referring to is the dot matrix print identifying the pipe manufacturer, size, etc. The 'coating' may only be a draw compound, but I still need to get down to shiny steel for the parkerizing to work! The tubing is 1-7/8" OD x 1-3/4" ID.

unclesyd: What kind of media do you recommend for this?

Thanks,
Vince

 

[unclesyd]

I would imagine that you would use a plastic or synthetic media plus a suitable compound if wet, but I would hate to give a specific recommendation on media for your operation so I’ll have to defer to the media experts. We bought our vibratory/tumbling media from Victor Metal Finishing. My contact was Mr. Victor Briosi whom I consider to be well versed in the art and I do mean art. As they are quite a number of directions you can go I would definitely talk with an expert with a knowledge of the industry. I would get a heads up on the types of media prior to request information or as they say now “get up to speed”.

http://www.vicmetals.com/Supplies/PC_media.html

Here is one manufacturers of the media, in fact one that is sold by Victor.

http://www.vibrafinish.com/index.html

 

[sparkout]

As your first thread mentioned, both sandblasting and wire wheeling are time consuming, I've done surface finishing with a wire wheel mounted on a centerless with good success, and great throughput times, more pressure can be applied to piece through the regulating wheel than ever could be done by hand creating a much more uniform finish. This would be a good process if number of parts to be done were in large enough quantities.

 

[Ductmate]

I don't have a centerless, it's just a wire wheel on bench grinder. It's not that slow, just too easy to miss a spot!

Also, cost of the equipment is something of an issue for me. A small blast cabinet wouldn't be very expensive.

Vince