Removing dross, mill scale from plasma cut parts

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cjdauthier
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Removing dross, mill scale from plasma cut parts

Post by cjdauthier » Sun Aug 21, 2011 9:51 pm

Just wanted to pass along my experience with this...I have read several posts on this on here, and wanted to share....I started out the old fashioned way....abrasive disks and flapper wheels. They, of course, will do a great job of removing both dross and mill scale....just takes forever, especially when you have a couple hundred small pieces to do.....I then decided there had to be an easier way...so after doing some reading on tumblers, I built one out of an old propane tank with a 4 wheeler winch motor and bike sprockets for the drive gears...worked great...if you let it run for hours and didn't mind the noise....both of them were a pain to me...finally did a little more digging, and found the posts about muriatic acid...mixed 1:1 in a large platic drum...I cut the pieces, take them straight off the table and throw them in the acid solution...most pieces, even with heavy dross (I get in wayyyy too much of a hurry moving different thicknesses of sheets on and off, and alot of time just let her eat) are done in a few hours...mill scale, dross...all gone...just avoid the fumes, and save yourself some time...and work!!!!

I know this is well known to alot of you...but there may be a few people who, like me, were beating themselves to death with grinders and wire wheels....just wanted to share ;)

M & N Steel CNC
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Re: Removing dross, mill scale from plasma cut parts

Post by M & N Steel CNC » Tue Dec 27, 2011 7:52 pm

OK, i am new to this, 1;1. muratic acid to what????
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Dawgonhawg
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Re: Removing dross, mill scale from plasma cut parts

Post by Dawgonhawg » Tue Dec 27, 2011 8:15 pm

The muriatic acid works well but how do you handle the rusting which starts very soon after using the acid?
Thanks, Dawg

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Re: Removing dross, mill scale from plasma cut parts

Post by Kentuckyfarmer » Tue Dec 27, 2011 9:14 pm

One part acid one part water
As to rust I wash the parts of with clear water after removing from acid tub and dry with the forced air kerosene heater this time of year, rust has not been a problem
hope this helps
Mike

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Dennis
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Re: Removing dross, mill scale from plasma cut parts

Post by Dennis » Tue Dec 27, 2011 10:12 pm

Can you post up a couple pics ---- Like a Before and After..

Thanks Dennis

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Re: Removing dross, mill scale from plasma cut parts

Post by boodog710 » Wed Dec 28, 2011 6:53 am

Mike, I have been using muraitic acid for several years now. After I remove the parts from the acid I put them in a solution of water and baking soda. This will kill any acid left on the parts. Only takes about a minute. Then I dry them and apply a thin coat of paint thinner. This will stop any rust. Works really great with a bunch of small parts. On large parts I use a sheet rock joint knife (6"). I simply knock the dross off with it. Then a light round with a grinder.

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Re: Removing dross, mill scale from plasma cut parts

Post by Kentuckyfarmer » Wed Dec 28, 2011 7:46 pm

Yea Jack I have used the baking soda after wash also it helps alot, I think the most important thing is a good rinse and quickly drying them dont hurt .
Mike

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Re: Removing dross, mill scale from plasma cut parts

Post by DARRYL21270 » Tue May 29, 2012 11:46 pm

What are you guys storing your muriatic acid in. I just ordered a 40 gallon parts washer and was hoping I could fill that with my acid/water mixture or do you recommend using something else to soak pieces in?

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steelfx
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Re: Removing dross, mill scale from plasma cut parts

Post by steelfx » Wed May 30, 2012 12:07 am

DARRYL21270 wrote:What are you guys storing your muriatic acid in. I just ordered a 40 gallon parts washer and was hoping I could fill that with my acid/water mixture or do you recommend using something else to soak pieces in?
I use a 300 gallon HDPE (Poly) Horse Trough. But I only have about 3 or 4" of solution in the bottom. That size
tank allows me to submerge a 4.5' X 3.5' piece w/ no problem. Keep it at least 50' or more from anything you don't want rusted, though & keep it covered when you're not using it. Muriatic (Hydrochloric) Acid is actually a gas that is suspended in water. Typically, the Muriatic Acid you buy at the hardware store is a 35-40% solution. Even diluted 1:1 with water
the fumes (gas molecules) escaping will rust anything in range.

There are "scentless" muriatic acids available, but they'll still rust things you don't want rusted & in my opinion, they're not as strong and effective as the regular. My favorite brand is TransChem?.

Bill

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Re: Removing dross, mill scale from plasma cut parts

Post by alleykat » Thu Nov 01, 2012 1:15 am

I will have to try this soon.I got a new 4x8 sheet of 1/4 inch steel and the mill scale is HEAVY.Taking me way longer than usual to sand blast my cut parts.
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alleykat
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Re: Removing dross, mill scale from plasma cut parts

Post by alleykat » Mon Dec 31, 2012 4:15 am

Finally tried it with some stuff I got from Home Depot.

Bucket 1 w/lid
2 gallons muriatic acid
2 gallons water

Bucket 2 w/lid
4 gallons water
Small box of baking soda dumped in

Left my parts in there that had heavy mill scale on them,checked 30 mins later WOW why didn't I try this sooner. :shock:

Basically just let your pieces soak,remove them once you see they're clean and dip them in the water/baking soda solution.DO NOT rinse them with just water after you dip them in there.I tried this and it left baby surface rust on them.I find it better to just dip it in the water/baking soda and then dry them with compressed air.

I media blast everything so even the baby rust is still wayyy better then having to blast thru that mill scale.My time working on things has been cut drastically.
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elwoood
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Re: Removing dross, mill scale from plasma cut parts

Post by elwoood » Mon Dec 31, 2012 5:57 am

I had posted this sometime ago but here it is again.
I use common white vinegar. I put a gallon or two in an old rubbermaid tub and let my parts soak a couple of hours or overnight. Wash with plain water and your done.
Advantages: Low cost 1.68 gall
Buy it from any food market--or the dreaded Wally World
No toxic acid related issues
Safe disposal- throw in some baking soda when done, pour down the drain or dump outside. It is safe right
out of the bottle, the greenies can't complain.
If some spots don't come off wet a paper towel with more vinegar, place over the spot, come back in a
couple of min. and the spot will grind right off.
Smell- yes your shop will smell like vinegar, add fresh thyme or rosemary- problem solved.

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Re: Removing dross, mill scale from plasma cut parts

Post by sonofmitch » Mon Feb 11, 2013 5:25 pm

Does all this work on stainless as well?
Mitch

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Re: Removing dross, mill scale from plasma cut parts

Post by Gamelord » Mon Feb 11, 2013 8:16 pm

I tried stainless in muriatic acid and it did absolutely nothing. Mill scale stayed, dross stayed.
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