anyone made a mill scale remover?

[bigbadbugga]

Would the two roller method work with some really stiff wire brushes welded on shafts instead of abrasive paper.

This type, http://toolstoday.co.uk/product/18113/draper-75mm-twisted-wire-wheel-41434-349p?cat=2579

Or even big flap wheels, as they would flex more.

 

[Drains]

The price difference between hot rolled mild steel and annealed bright steel is hefty.
So I was wondering has anyone contemplated or fabricated a tool to easily remove mill scale from lengths of flat, round and square bar.

Why?

And since when was bright steel annealed? The two materials are quite different in many respects as bright is cold rolled, so much harder and springier - even though they might not be different formulations of steel.

Mill scale doesn't need to be removed for working and welding or painting - unless you're using an epoxy finish, in which case you should ideally blast anyway. If you're varnishing, well that's different.

Rather than some fancy planer thicknesser, a multi-head shot blaster and vacuum set-up would be pretty cool. Feed the steel through, in dirty, out clean, no media all over the shop.

 

[Dev]

http://www.abrasivesformetal.co.uk/Stripping-Wheel-Brush.aspx

Big rollers of abrasive. Bloody expensive though.

Why?
Rather than some fancy planer thicknesser, a multi-head shot blaster and vacuum set-up would be pretty cool. Feed the steel through, in dirty, out clean, no media all over the shop.

That does sound pretty cool. I don't know anything about shot blasting, can you get some sort of fan spread nozzle? It'd also handle round sections better.

 

[KemppiFrog]

I use hydrochloric acid, diluted at around 3:1. Mainly because I can get it at the local supermarket for about €1.50 /ltr. Not too quick, but works. Blasting is the way and I am working up to it. Making a roller machine or similar, sounds a LOT of work when a quick dust off with a flap disc could get the same result. Unless you are into big quantities, then back to blasting.

The Hcl also goes green after use. And it does work for forge stuff. The scale is the same oxide as mill, sort of logic
KF

 

[KemppiFrog]

I wonder why it goes green... I have an antibacterial powder that's added to water to stop algae forming, I wonder if that'd help. Just out of curiousity.

No, the green colour is not related to bacteria.

 

[Dev]

While looking for post cleaning protection ideas I came across this http://www.npl.co.uk/upload/pdf/temporary_corrosion_protectives.pdf

Quite interesting, I had no idea you could get wrappings that actually released a vapour to prevent corrosion.

 

[chunkolini]

The green colour?
What is the chemistry? when rusting steel with ammonium Chloride it sometimes goes the same weird green colour. Never made the connnection before.
Dev, is that 'Magic paper.
Brown slightly tacky feel to it that they used to wrap tools in. My old man swears by it.

 

[Bsmith]

Dev, is that 'Magic paper.
Brown slightly tacky feel to it that they used to wrap tools in. My old man swears by it.

Used to get 'Damp proof paper', like strong brown paper with oily wax on one side. Engine parts, bearings etc came wrapped in it.

 

[KemppiFrog]

Not sure about the chemistry, but both involve chloride and chlorine tends to produce green products. I had a problem with my chem teacher at skool and switched to a DIY Mech and Tech drawing program.

Edit: While flap discing off some scale today, some comes off easily, some not. I very much doubt that wire brushes would do a good job on a single pass. Perhaps those spiral wound ones with a lot of power, but..but.
KF

 

[the snooper]

I had a problem with my chem teacher at skool KF

and english teacher

 

[bigegg]

Used to get 'Damp proof paper', like strong brown paper with oily wax on one side. Engine parts, bearings etc came wrapped in it.

It can be obtained from Samuel Grant's -

http://www.samuelgrant.co.uk/prodpage.asp?productid=21

Doesn't look to be available to order directly from the website,
but was definitely available from the trade counter on Dewsbury Road, Leeds.
(Tell them "the book man" sent you )

 

[KemppiFrog]

and english teacher

never heard of Molesworth?

 

[the snooper]

 

[rtbcomp]

There's a paper called "vapour phase inhibitor" you just put it the box with the item you wanted to protect, it was quite light compared to the heavy waxy stuff.

 

[Dev]

Sounds expensive.

 

[malcolmsmill]

I know its an old thread but mill scale is still problematic........... I'm going to try the citric method... the green colour is the iron in the scale dissolved in citric acid... ferrous citrate is green coloured as are ALL iron salts.

BTW phosphoric acid, as in rust remover/ preventer/coating is stronger in pepsi or coke "Max" drinks than in most products (if sugar version is tried, you get the problem of removing sticky sugar residue..

at work we had a 2mtr wide machine with a full width wire roller... it removed scale from steel and left a fine "scratched" surface on steel or aluminium ready for wet paint or powder coating

 

[malcolmsmill]

ODDITY.... sulphuric acid will dissolve almost anything (inc fingers) but will not attack mild steel, it does attack all other types, which is why commercially sulphuric acid is stored in mild steel tanks

I will NEVER succumb to the american sulfur spelling.... even though it IS the historically correct UK English spelling (as is Aluminum correct.... a publisher added the extra "I" in alluminium and "ph" not "f" in sulphur, because he thought it looked nicer on the page

 

[stuvy]

A ten year old thread

 

[Ross365]

By "mill scale" are we talking about flakes of iron oxide? In big business, the traditional way to remove it is by using a mixture of hydrofluoric and nitric acid. However, hydrofluoric acid is seriously dangerous stuff (more so than the other acids). I've never tried citric for this purpose but suspect it would be slow. Phosphoric and sulfuric acid can form layers of metal phosphates or sulfates, which is not what you want.

Re sulfates or sulphates, the bodies that govern chemical terminology in the UK agreed to adopt sulfate a few years ago. Progressively, all UK Government documentation is adopting the change. I think the driving force was something to do with the software used to transform documents in to speech for blind people.

 

[MetalMonkey]

Zombie thread!

Hydrochloric/Muriatic is the quick and easy DIY way to remove mill scale. It does rust everything else in sight and may not be ideal for any critical process.
I've had good success with strong Acetic acid (Vinegar) - takes longer but much more friendly to deal with.

Phosphoric acid is a rust convertor, won't do much for mill scale and easier to buy it in a concentrated form than muck about with soft drinks IMO.
I've not tried citric acid, but I'm sure somebody on here said it worked well.

Sandblasting or abrasive removal is also an option, but not a pleasant one if you have any quantity to do.