I recently opened my small shop and already have a few customers, but I’m running into a bottleneck in production. I’m spending a lot of time removing mill scale and slag from parts. Most of my orders are 200+ parts, ranging from about 7” to 10” in diameter.
I’m trying to speed up my process so I can get to painting faster. I’ve been considering either a benchtop drum sander or a sandblasting cabinet, but I’m not sure which would make more sense for this kind of work. Do you have any recommendations or ideas for a more efficient way to handle this cleanup step?
One requires a lot of CFMs (sand blasting) and another requires space and more money (belt sander setups).
We don’t know what works for you in that regard.
As far as ‘dross’, dial in your setup. Dross underneath is normally due to slow speeds while cutting. Unless there are cut paths close to each other which will warm up a part of the steel quite a bit, all my metal comes out dross free from 16 gauge to 1/4”.
The product I make is required by the call out for hot rolled steel . I have a good program that runs little to no slag . I just have to get the steel to be bare. Just trying to find the quickest
Since you don’t mention what type or thickness steel you are using, I’ll assume 4’ x 8” sheets. Have you considered buying cold rolled? That will pretty much take care of the mill scale. Then as others have said, keep working on machine settings to minimize dross.
Another option is soaking in concentrated vinegar to remove the mill scale. You could do that either pre or post cutting, depending on shop space and part volume. If you’re high volume, I’d consider building a 4’ x 4’ tank that half sheets could stand up in and build a rack inside the tank. 18-24 hour soak and mill scale is gone. You do need to rinse and dry quickly to prevent surface rust.
Sorry it’s 1/8 hot rolled steel . I would love to do cold rolled steel but my supplier has to special order that thickness and above. Yes is use 4x8 sheet
Another vote for vinegar. Don’t bother with specialty grade solutions, just buy gallons from your local supermarket/costco type store. Should be $1-2 per gallon or so.
Pick up a few commercial grade trash bins - heavy duty rectangular ones work best for flat parts.
You could even get fancy and buy a rolling trash bin, or just put them on dollies. Often times, 55 gallon drums can be found for free or cheap on marketplace, and are significantly more sturdy than most trash bins. Another option for large scale is an IBC tote, also found on marketplace. You may have a local beverage/chemical supplier that could sell you 55 gallons of vinegar, which you could then pump into smaller containers, or dilute into an IBC tote.
You can make a basket from expanded metal, and use a $100 harbor freight hoist to lift the basket in and out of solution. Separate tank with baking soda to neutralize, and you’re set.
With a little agitation or a light brush, most everything should fall off. It seems as though slag will stick to the scale, so once you separate the scale with vinegar, the slag falls right off as well.
Otherwise, modified harbor freight concrete mixer and some media to knock the slag off. Professional sized vibratory tumblers (think washer machine size) exist, but are expensive.
Vinegar or citric acid will take off mill scale with an overnight soak. I have it in one of those storage containers that you can slide under a bed. It has a lot of area, but isn’t too deep.
I really appreciate all the help with the ideas I am going to go with a vinegar bath. I actually thought about the concrete mixer using it as a Tumblr thank you everyone
Well the vinegar is just for mill scale, not dross. And you do need to rinse it off right after removing the steel from the bath or it will develop rust very quickly.
I don’t know who your steel supplier is, but you might want to ask them about Pickled and Oiled (P&O) steel. It is chemically treated to remove scale, and is then lightly oiled to help against rusting.
It costs about 20% more, but saves an awful lot of hastles. The plasma jet isn’t affected by the oil, so you can throw it right on the table, but you will need to remove the oil before painting with a de-greaser or acetone or gasoline or anything that comes to hand.
Never done any powder coating before, I use Tremclad. I would think as long as the material is clean, with properly rounded edges, the powder coat would stick just fine.
Maybe some others on the forum who know about powder coating can answer that one.
The dross on the back I dial it in to little to none . It was the mill scale that’s killing me. But know with the vinegar and the p&o I think I will be ok