topic 26572

Tumble polishing stainless steel

A discussion started in 2004 but continuing through 2018

(2004)

Q. What is recommended for tumble polishing stainless steel castings (RMS 72) to a full mirror finish? The parts are of an "S" shape with corner radii of .093, weighing approx. 5.8 oz. Hand finishing is a definite NO-NO and a waste of time. Can someone advise me?

Thanks,

JC Marcotte
toolmaker - Sudbury, Ontario, Canada

(2004)

A. Wow! That's rough. Are you sure that isn't RA? Normal mill steel is made to about 35 RMS. That means you roughen it up some more? If that is the case, you're talking about at least a 3 step and maybe 5 step mass finishing process. That much material removal will also work harden parts. Suggested procedure is to get and use the largest, coarsest ceramic media and run for maybe 2 to 8 hours at the maximum amplitude of your machine. Repeat with medium cut and a fine cut. You might also want to consider using a chemical accelerator instead of a normal deburring compound.

AF Kenton
Nova Finishing Systems Inc.
Hatboro, Pennsylvania

(2004)

How to Polish Stainless Steel

A. In a tumbling barrel, max. efficiency is obtained when the barrel is loaded to about 60% of its volumetric capacity. For the mirror finishing on S.S. components, I would recommend
Step 1: Ceramic Media, Abrasive Grade.
Step 2: Plastic Cones, Medium Abrasive Grade.

Chemicals are available for such finishes that expedite the process.

Regards,

Niranjan S. Kulkarni
finishing machines - Thane, Maharashtra, India

February 11, 2016

Q. I make custom bracelets and am trying to get mirror shine on 302 ss wire. I tumble for hours, it seems like, but it always turns out the same finish with the ss pins I am using for the final polishing step. I am looking for a mirror finish and do not know if they make a chemical that will assist in the finishing, or do I need to approach this from a different methodology?

26572-1a 26572-1b

3 lb tumbler --
1st plastic resin abrasive br 2nd step ceramic polishing grade
3rd step ss pins with brass polishing compound

kenneth milby
- hernando florida

February 11, 2016

A. Kenneth,

There are two possible ways to polish such complicated form: the first method is do do chemical polishing. Testing needs to be conducted in order to adjust the chemical composition to the alloy type and to level of roughness of the specific design.

The second method is to use plasma electropolishing. Plasma will penetrate into each hidden areas of the stainless steel chain. However this method is more expensive, and may not be justified.

Anna Berkovich
Russamer Labs

Pittsburgh, Pennsylvania

February 12, 2016

A. Good day Kenneth.

In my past experience with tumbling, I have found using ceramics can be quite aggressive on the substrate. Are there any material defects produced during manufacturing that you are trying to remove with ceramics? I would think the SS pins and a proper "soap"compatible for SS burnishing would suffice.
Try using fine ground corn husk (can also be used heated on a hot plate to dry the jewellery) and rouge compound as a dry tumble for the finish/polish you need. There is (was?) a company dealing with jewellery mfg. supplies, namely GESSWEIN, they may offer more insight.
Hope this helps.

Regards,

Eric Bogner, Lab. Tech
Aerotek Mfg. Ltd. - Whitby, Ontario, Canada

February 16, 2016

Q. Okay, lets see if I can answer all of the questions --

I got the ceramic idea off of this blog and just tried it.
I am interested in the idea of chemical polishing; what are the average costs on something like that?
I have not tried the walnut, nor the corn cob with rouge. I have not been able to locate the rouge.
I am currently using the ss steel pins with water and a little soap. Is there a specific type of soap I should use?
The last question was what imperfection, and I would say no the wire is smooth and shiny but not what it could be. I believe it would help me sell them if they were polished to a mirror finish.

kenneth Milby [returning]
- hernando, Florida

February 18, 2016

A. It sounds as if the first step is too aggressive. Also, I have never worked with a magnetic tumbler and again cannot verify the finish you are getting; however, it sounds as if the compound might be the problem. A mechanical dry treated organic process always gets you a mirror finish but in smaller machines, this can take way too much time.

AF Kenton
Nova Finishing Systems Inc.
Hatboro, Pennsylvania

March 10, 2018

Q. Hi, I am making stainless steel jewelries. I am planning to use stainless steel blanks, graphic stickers to stick on the blanks and then coated with epoxy resin. So I want my blanks to be shiny at the rim area and also want to make sure the sticker and resin bond to the stainless steel as well.

So my question is if I do tumbling on the the stainless steel to give a shiny look, the glue from sticker and epoxy will stick to stainless steel or not? Normally most people recommend to abrade the stainless steel before coating with epoxy. Can tumbling be considered as abrading?

Soe Thein
- Singapore

March 16, 2018

A. Any coating will stick better to a rough surface than a smooth one; however, if that coating is thin it may not cover the peaks of the roughness. There is a trade off and as long as you do not burnish surface, it sounds like you can achieve what you are looking for.

AF Kenton
Nova Finishing Systems Inc.
Hatboro, Pennsylvania

April 9, 2018

Magnetic Tumbler

Q. Hello,

I have recently bought a magnetic tumbler after reading about how good and efficient a polishing machine it is. The first item I polished was a SS small part. After 30 mins of tumbling, the ring was dull and had a frosted finish or what others call an orange-peel effect. I then noticed on the product page of the website that says: "Not a Final Polish May leave behind an orange peel effect on smooth broad surfaces."

So I tried to polish smaller items like a few pairs of gold and silver earrings. They too came out looking dull and frosty. Other items such as bracelet and necklace came out okay but I find the finishing quality inferior to that of a rotary tumbler.

I've tried using liquid and powdered burnishing compounds, experimenting on different amount of water used and extending the tumbling time but to no success. I have seen videos in youtube and read online articles showing how bright and shiny a seemingly plain ring (among other jewelry) can be after it has been tumbled in the magnetic tumbler.

The good thing about it is that it doesn't remove delicate designs on the jewelry during the tumbling process and produces a very even finish.

So what did I do wrong? Why am I struggling to get a bright and shiny finish as advertised? How should a magnetic tumbler be used in conjunction with other polishing tools? Also, should I polish my now frosty-looking ring with Tripoli then rouge or can I just skip it and apply rouge instead?

Any help is greatly appreciated!

I will upload photos my work and comparisons upon request. Thanks!

Adnan Minhas
- karachi, sindh, Pakistan

April 10, 2018

A. Hmmm. it sounds as if you are running the machine at too high an RPM. If there is no adjustment for speed then run fewer parts. Another important issue is the chemical compound, also the quality of the water may play into this. Then again, make sure you have a good grade of SS pins.

AF Kenton
Nova Finishing Systems Inc.
Hatboro, Pennsylvania

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