Finishing 316 Stainless Steel? 1

[qcrobert]

We are wanting to obtain a sanitary finish of 42 Ra. Presently using a sanding disc to knock down the weld seam bead, then 80 grit and finally 150 grit.

Does anyone here have experience in obtaining this finish.

Would appreciate any information or suggestions.

Thanks,
Robert

 

[EdStainless]

Make sure that you don't use SiC abrasive.

What is your final passivation? My hunch is that you have smeared a lot of metal in this finishing. Maybe 60, 120, 180 would be a better route.

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Plymouth Tube

 

[qcrobert]

Client has not specified any passivation, just finished smooth (cotton ball).

Will start with 60 as you propose and end in 150 or 180 if client is not satisfied.

Thank you

 

[monkeydog]

What EdStainless is trying to point out to you is if in the process of obtaining your finish, you may want to passivate to eliminate the free iron.
Otherwise your customer will be sending your medical grade parts back due to surface corrosion.

 

[EdStainless]

If you don't passivate the surface will develop rust spots.
Folds, laps, and re-embedded metal will rust on exposure to humid air.
The point of using multiple grits is that you must fully remove the cut lines from each grit with the next finest one before moving on. You also have to make sure that you keep using sharp abrasive and low pressures so that you don't smear metal.

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Plymouth Tube

 

[qcrobert]

Thanks everyone for the valuable information.

Leading me to ask more questions to client of what to expect and what we are capable of.

 

[qcrobert]

Another question if you please.

We are finishing a SS vessel to a #4 surface finish and would like to limit the finished surface on each side of the welded seam to approx 2" or less.

My Q is is there a type of tape that will mask of areas that a buffer will not permeate?

Appreciate any comments,Robert P.

 

[EdStainless]

Not that I have ever seen. All of the masking products that I know of would be torn up in the grinding/polishing.
Don't you have to blend the weld lines into the general finish?
If you are covering too much area maybe you need to use smaller finishing tools.

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Plymouth Tube

 

[qcrobert]

Yes, weld seam to be ground down then subsequent polishing steps.

Client is wanting a straight demarcation line betw polished area and remaining unpolished surface.

More comsmetic than anything else....

 

[qcrobert]

Found the masking tape I needed, it is stainless steel shim stock tape!