Vibratory Polishing of Stainless Steel Components

A. Sundeep There are a couple of things that you can look at to improve your finished product; however, not knowing what your process is, I can only make some guesses.

Tony

A. Mr.Khandelwal,

The most efficient and the cheapest method for brightening stainless steel hinges is vibratory (wet) burnishing with stainless steel balls. The (rectangular bowl) burnishing machine (which is rather expensive) must provide 3000 vibrations per minute and have, preferably, an automatic discharge system. In such a machine, the parts are brightened in 10-20 minutes, using an appropriate liquid compound. An important condition is that parts must be perfectly degreased (in an alkaline cleaner) and pickled (in a hydrochloric or sulfuric acid solution and rinsed) before introduction into the machine. The burnishing may also be done in rotating barrels made in stainless steel or steel with interior rubber or polyurethane lining and containing stainless steel balls (2/3 of the volume), water the brightening compound and the parts. But the brightening time will be much longer (12 hours or more).

A. MR KHANDELWAL,

I SUGGEST A STRONG DEGREASER IN VIBRATORY MACHINE TO REMOVE THE OIL OR BLACKNESS AND THEN BURNISHING USING STEEL MEDIA FOR 60 MINUTES. YOU WOULD REQUIRE A SPECIAL MACHINE FOR BURNISHING AND STRONG ACIDIC COMPOUND FOR BURNISHING.

A. Mr Khandelwal,
I suggest you to save time and improve the quality of s.s. parts use liquid deburring and polishing chemicals (citric acid based).

A. Hi Jayesh
Matte finishes are certainly much easier to get:-)
Mirror finishes require no scratches except super fine ones, which in turn means smoother media and finer abrasives, which means it can take forever to get from raw to finished when you try to do it in a single step with only super fine abrasives.
Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. You must use steel ball media. Meanwhile, to move the steel ball, you need to change your vibrating machine and buy a vibrating machine with a reinforced motor. Because the machine you are currently working with cannot move the steel ball.

Please send a photo and video of the part, as well as the description of the vibration and polishing process, so that I can guide you better.

A. Hi Nick, Ashish, Karan. Are you sure that your thinking is correct?

While it is possible to put a very fine polishing media into a vibratory finisher for mirror finishing, the problem is that it takes nearly forever to do a very big job with a very tiny tool.

This abrasive finishing problem can perhaps be recognized by picturing the digging of the foundation for a skyscraper with a teaspoon. Abrasive finishing often must be done in several steps, using progressively finer media, if it is to be practical. Good luck.

Regards,

A. PJ's problem is different from JS. Size is the factor along with time. PJ could use a small vibratory mass finishing system using dry organic abrasive and polishing media. JS has volume to consider as well as finish. I am leaning to an automated buffing machine system because of the size and shape. Cost of such a system is a lot higher than mass finishing, but it would be faster. I think if you are looking for brightness rather than smooth, it can be done in a vibratory machine with dividers or a pass through system in a wet process.

A. Thank you for providing the volume numbers. I could have saved you some time and effort. OK. If you are not concerned with the RMS (surface finish) you can probably process this volume through a 10 cu.ft. vibratory machine using either steel or porcelain media in a wet burnishing process and a good chemical compound. After the media is broken in you should be able to improve the brightness of the product at a rate of 500/hr. The parts will look good but the finish may not be smooth but under 24RMS. If you like what you are getting now, stay with it or convert to an automated system.

A. Dear All,

Thank you in advance to Mr. Kenton! I'll try to repay the favor!

Mr. Jagadeesan Sankaran, I think you have to search a solution with an automatic polishing machine. I would like to help, but I need more information about your product or all the products that you have to polishing.
Can we see a picture or technical drawing, of the product? I don't understand the dimensions of your product. Do you grind before polishing? How many hours per day do you work? 3000 pieces of one single type or different model?

Thank you for your information.

A. Yes, Jagadeesan, it might be possible to electropolish your items instead of buffing them. Please see the excellent chapter on electrolytic polishing in the Electroplating Engineering Handbook [on AbeBooks or eBay or Amazon] to understand all the implications of whether the process may be applicable to your components.
Be warned, though, that switching from buffing to electropolishing to save labor costs may introduce some new problems for you. Best of luck.

A. Sorry Ted, but the electropolishing has three big problems:

- Firstly, you cannot get mirror finishing on the metallic surface after electropolishing. If you take a SS product after this process you can't see your face reflected on it. So you cannot get the mirror finishing.
- Secondly, electropolishing is heavily polluting as a process.
- Third, the price of equipment and consumables.
I believe that we misinform, and suggest implementing automatic polishing.

Please, if you have any question I'm available!

Alvise Carraro
- Padova, ITALY

Hi Alvise. Thanks for your help! But Jagadeesan specifically said: "Can anyone give me dipping method?" -- so I did.

But yes it is certainly possible that automatic polishing is a better answer for a given situation than electropolishing -- it often is!

Every technology has advantages & disadvantages; none is "best" except in response to a detailed list of exactly what parameters are most important for the specific case. For example, every mechanical finish, no matter how fine, resembles a farmer's plowed field, it's only a question of what magnification is required to reveal the clods and furrows, whereas an electropolished surface resembles gentle ocean swells. For this reason many dairy and pharmaceutical suppliers will never accept mechanically polished stainless steel -- electropolishing, with its freedom from those nooks & crannies, is a non-negotiable requirement for them. Since the best answer to such questions always depends on their details ... when someone insists that their proposed method is better than a possible alternative method, while simultaneously noting that they don't yet have any facts about dimensions, production rates, process sequences, work schedules, etc., the objectivity of the proposed solution might be questioned :-)

Thanks again, and regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. Thanks, Jagadeesan. But I think the ball is still in your court re. automatic polishing equipment. As I read the thread, Alvise is waiting to hear typical dimensions of your product, whether you grind before polishing, how many hours per day you work, and perhaps of the 3000 pieces per day, maybe how many of the size you do the most of (maybe it's impractical to automatically polish specialty items that you do only a few of).

A. Hi. You must use steel ball media. In addition, your vibrating machine cannot move the steel ball, so it must be replaced or its motor strengthened. In addition, so that your parts do not collide with each other during the polishing stage, you must Use a cover.

A. In your present wet process, are you working these parts in a batch with liquid closed, or are you recirculating? Maybe a flow through system, not closed loop will work better and produce consistent results.

A. DEAR,
FOR HIGH GLOSS OR MIRROR FINISH ON SS YOU WILL HAVE TO GO FOR ELECTROPOLISHING AFTER VERY GOOD DEGREASING.