what people use for finishing stainless steel? 1

[Rossco1]

we use stainless for shop fittings and want to have a good finish for our clients .
problem is it takes us ages to get to that standard .
Now what im after is grinding disks and other options for getting a good even finish .
we have tried 3m disks 2 80 grit for getting welds off but it is to rough and tends to leave cavities (some of the staff r a bit rough and ready as well)
ANY and all suggestions welcome
thanks

 

[mcguire]

Rossco1
First, it depends on the finish on the unwelded part of the component. Ideally you want to not be able to see a weld. That is the norm for appliances and restaurant equipment. This requires grinding to make it nearly flush, then finishing with finer and finer grit abrasives until you get to the roughness of the rest of the surface. 3M sales guys have a lot of technical backup; ask them to give it to you. That's what it's there for.
Remember that after all the grinding and polishing you need to pickle(acid wash) the surface so it doesn't corrode to easily.
If the guys working the sanding wheels haven't done a great job, you can buff with fine abrasives to blend the weld to the rest.

 

[EdStainless]

There is a fine line. Most abrasive finishes that you see on stainless are about a 180 grit. You want to make sure that you cut and not smear the surface. The slight grit lines also help hide some minor surface blemishes as well as finger prints.
Don't use SiC abrasive. Do finish in steps, 80 first then 120 or 180 to finish. Make sure that you abrasives never get used on anything other than stainless.
A pickle or passivation after finish is required. ASTM A380 lists methods of passivation and A967 lists test methods to make sure that the result is correct.

You do many things when you passivate.
1. You remove surface impurities (mostly Fe) that can start early corrosion.
2. You remove microscopic fragments of torn stainless on the surface that can also be locations for corrosion initiation.
3. You force a stable surface film to form which offers the best corrosion resistance.

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Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[unclesyd]

Depending on what particular type fitting you are referring to it is less expensive to purchase pre finished fittings if possible.

Comeback with what particular fitting you are concerned about.

 

[Rossco1]

^Thanks for the replys guys,
EDSTAINLESS
PLease tell me what SiC is please?
we also use a sanding pad that has (by 3m) that has scotch bright attachd does ok for certain applications.

uncle syd
we make all our own fittings from scratch , ie cut tube to length weld blah blah.
thanks

 

[EdStainless]

The ScothBrite works fine.
SiC is silicon carbide, it is a common abrasive. It is very hard and can imbed in the surface creating sites for corrosion to start.


= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm