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Is finishing always done after cutting?

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D.O.T
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Is finishing always done after cutting?

Postby D.O.T » Mon May 07, 2018 9:12 pm

Hello folks,

First thing is first, i am not a machinist but a customer who is interested in purchasing a stainless steel plate and having it cut using a DXF file with a plasma cutter at a stainless steel center and distributor called Diversified Ulbrich (DU). My main problem is that i am not a professional and for this reason i am totally in the dark about how things work. Normally i do as much research as i can to not waste peoples time in forums, but right now i have hit a road block and i cant find the answers online. So here goes my questions regarding finishing.

DU says they offer the following finishes on Stainless Steel Plates: #1 HRAP, 2B, #4 Polished, Checker/Diamond, Clad.

And this is where i get confused. The confusion is because normally the finishing is done after the plasma cutting. But if they offer Checker/Diamond finishes then that finish would certainly be done at a steel producing factory and not with DU - which means the finishing is before the plasma cutting with DU.

And so, my question is which is it? Are all the finishes pre done at a steel producing factory or are they done after the cutting with DU?

Also, what if its both? In other words, what if for something like the 2B finish, which is what i want, it is done after the plasma cutting, but for the Checker/Diamond finish, it is pre done before the cutting at the steel producing factory.

Here is a link to the DU web page with the information for stainless plates and finishing.
https://www.diversifiedulbrich.ca/products/plate/

Any information and advice would be greatly appreciated.

Thanks.

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Re: Is finishing always done after cutting?

Postby djreiswig » Mon May 07, 2018 10:29 pm

I believe on stainless the finish is done at the steel mill. It comes this way as sheet goods. The diamond finish is actually like a tread plate that would be used on something like a trailer deck. It has the raised pattern made into the material. Polished is, well, polished and shiny. Not sure on HRAP, 2B or clad.
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D.O.T
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Re: Is finishing always done after cutting?

Postby D.O.T » Mon May 07, 2018 11:26 pm

I will take your word for it. I had a feeling the finishes were done at the steel mill.

Thanks for the info.

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Gamelord
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Re: Is finishing always done after cutting?

Postby Gamelord » Tue May 08, 2018 1:09 am

I will agree with the above. The finish is most likely from the mill. The plasma will cut without doing any damage to the surface (if they are careful enough). One thing to consider is the type of plasma cutting they plan on doing. If it is air plasma, the edges of your stainless will come out blackened and a little coarse, not smooth and polished like you get with steel. I believe with nitrogen the edges come out a lot nicer. Either way if you want the finish on the edges of the piece, that will usually come at a larger cost. I would ask them for some samples or pictures of pieces they cut and make sure that it is what you are expecting. Just make sure it is of the same type of Stainless (304, 316, etc...) and the edges are either raw or polished after the cut.
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D.O.T
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Re: Is finishing always done after cutting?

Postby D.O.T » Tue May 08, 2018 11:55 am

Hi Gamelord,

You mention that if they cut the plate carefully then they wont do damage to the surface. Does this mean i can request that they do the job carefully or is that what they automatically do and is not requestable?

Likewise, can i request that they use nitrogen instead of air or is that something that they decide on? Or for that matter, is that something that is not even optional for a single machine? In other words can a machine have the option of using air or nitrogen or does each machine come with only air or only nitrogen?

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Re: Is finishing always done after cutting?

Postby djreiswig » Tue May 08, 2018 7:44 pm

Instead of "careful enough" he should have said "not careless". The cutting should not normally have an effect on the finish.

Air plasmas and nitrogen plasmas are two different machines/processes. You can ask which type of process they use. If edge finish is important, you may want to consider having your parts laser cut.
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D.O.T
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Re: Is finishing always done after cutting?

Postby D.O.T » Tue May 08, 2018 9:20 pm

Laser costs too much. If i have to work on something larger in the future and i take laser when i dont need it then i will be wasting money. For this reason i will be trying plasma first.

As for the plasma they are using i guess i can call them and ask. The problem is that i don't want to bombard them with too many questions since i am an amateur making a small order.

But one has to wonder that if they specialize in stainless steel, as they state on their home page, then they would be using a plasma cutter that would be optimized for stainless steel, which means they would most likely not be using an air plasma.

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Re: Is finishing always done after cutting?

Postby J3mbeck » Tue May 08, 2018 11:29 pm

All (or most) finishing is done before hand and the sheets are covered with thin vinyl to protect the finish. Not sure how they do it DU, but when plasma cutting stainless with vinyl (Laser Shield i think) it melts to the sheet and is a biz-atch to get off. Maybe they pull it off before hand. Laser is a whole different story. If you want it to be prefect tell them it's for an architectural project.

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Re: Is finishing always done after cutting?

Postby D.O.T » Wed May 09, 2018 9:20 am

It is strange that they would put the vinyl to protect the finish if many people will have to cut with plasma which will melt the vinyl. And removing the vinyl before cutting seems like an unnecessary added step. I guess i may have to consider using an unfinished plate and then doing the full finish elsewhere - assuming DU has unfinished plates which is information that is impossible to obtain from the limited information on their website. My thinking was that by using a finished plate directly from DU then i would simply have to do basic clean up such as dross removal and quick sanding and then the cut pieces would be good to go.

But speaking of dross i do have a couple of questions that i am really interested in knowing the answers to.

The first is who removes the dross if there is any after cutting? Would that be their job at DU or is it my job? I can understand if they are going to finish the part then they would remove the dross. But if they don't finish then do they simply send the raw cuts to me or do they still have the courtesy of removing the dross?

Second, will a 1/4" 304 stainless plate cut with plasma require some kind of deburring of the edges to remove the sharpness so that i don't cut my self when handling the cut pieces? I am hoping the answer to this question is no since using a hand held deburring tool means more work and sloppy imprecise work as well.

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Re: Is finishing always done after cutting?

Postby J3mbeck » Wed May 09, 2018 10:09 pm

Buy mill finish stainless, no vinyl. Use a belt sander with 60G belts if you want a #4 brushed finish.

D.O.T
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Re: Is finishing always done after cutting?

Postby D.O.T » Thu May 10, 2018 4:09 pm

OK so here is a quote from some other company regarding the 2B finish, which is what i am actually seeking.

"The 2B finish is a mill finish that is smooth, as opposed to the brushed finish commonly seen on kitchen appliances. The finish is light gray in color, and may or may not have a protective film on one side to prevent scratching. Customers can contact the sales department to see if the 2B finish has a protective film on the material if needed".

So basically i cant know if the 2B finish they offer at DU has a vinyl (PVC) coating or not. I can assume that if they are plasma cutting the material then they would be using a 2B finish that doesn't have a vinyl coating. But that's just an assumption.

I guess the best option for me to do now is to just send them one email asking all the questions i need answers to.

But going back to my other two questions that were not answered, who removes the dross after plasma cutting (me or DU), and do plasma cut parts of 1/4" stainless 304 plate need their edges deburred to make them less sharp?

J3mbeck
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Re: Is finishing always done after cutting?

Postby J3mbeck » Thu May 10, 2018 9:39 pm

Maybe ask them to remove the PVC. I would assume you'd want to remove the dross 'cause I'm sure they are going to put Carl, who is needing a smoke break on dross removal. better to do it yourself so you know it was done right. I don't like anyone but me or my guys grinding on my parts.

D.O.T
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Re: Is finishing always done after cutting?

Postby D.O.T » Thu May 10, 2018 9:54 pm

Ok, i will take care of the dross removal. I will notify them of that.

As for the PVC they clearly say on their website that they (DU) do it. My only concern is whether its also done at the mill, and the answer to that question is impossible to determine without contacting them.


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