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topic 13100

Vibratory tumbler/tumbler process and machine

Current question and answers:

March 26, 2021

Q. I'm looking at buying a new tumbler, some of them offer variable speed and I'm wondering how important/beneficial that is.

Billy Laumen
- Chicago Illinois
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March 2021

A. Hi Billy. Rotating at higher speed might or might not successfully shorten the cycle time. Has that been a serious problem for you with your old tumbler?

Although tumbling speed can effect the final finish, that's a difficult one to independently sort out when you consider that barrel diameter, type of parts, and the selected media all probably have larger effects on it than speed.

We have threads here about tumbling pewter, titanium, aluminum, stainless steel, golf club heads, coins, bearing components, brass fittings, Delrin plastic, jewelry, cartridge cases, etc., for everything from rough deburring to mirror polishing if you search the site. But it's probably hard for readers to usefully transfer their experience until they know what you want to tumble and why.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey
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March 28, 2021

Q. Hey Ted,

Thanks for responding.

We're a job shop so our work varies in regards to size and material and we put a premium on tools that have broad applications and so I'm wondering if the variable speed would broaden out the applications for any given tumbler. But I can give you an idea about what we do now and what we know to be upcoming.

Right now we have a inexpensive circular vibratory bowel, approximately 18 in at it's widest and about 8 inches deep. No variable speed. We put parts made from 4140 alloy steel and tool steel in this one to clean them up and break the edges. Shapes and sizes vary. I use ceramic media. I usually run parts in here anywhere from 5 to 8 hours. Speed here is acceptable. The finish is adequate for this particular family of tools. But I would like to have something that would better blend tool marks.

Going forward we're going to be working with some stainless parts, about the size of a quarter, though not always round. In some cases these quarter size parts will have copper or brass pressed into them. It's possible that we'll also be working with some titanium and tungsten carbide in the same size. Some parts are going to have a fair amount of detail engraved into them and this detail will have to remain readable. The big thing here is that they're going to want a really nice finish on these, mirror would be ideal, we might get away with near buff.

I'm looking at three different machines right now. A two bar rotary from Topline, here the barrel sizes vary with the biggest being 8.5 gallons. Dimensions are Diameter of 16 and a height of 15. You can buy smaller barrels, they go down to 8.25 Diameter 5.5 height, 3.5 quarts. (Can get in variable speed).

Another Topline machine I'm looking at is the DB300 rectangular tank 3 cubic foot. (No Variable Offered)

And finally I'm looking at Burr King's M 15 1.3 cubic foot (10 Gallon) circular bowl type vibratory tumbler (can get in variable speed).

Getting Two of these wouldn't be out of the question.

Any other advice or suggestions would be greatly appreciated.

Thanks

Billy Laumen [returning]
- Chicago Illinois
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March 2021

A. Hi Billy. Thanks for the detailed explanation of your situation and your thinking. Yes, it does seem that when you don't have a fixed assignment for the machine it would be worth it to get a variable speed unit which can be optimized for the task, especially for a non-vibratory tumbling machine.

I am not a mechanical finishing expert, but I believe that vibratory finishing shortens the cycle time dramatically compared to simple tumbling, so if you have no experience with simple tumbling you may want to investigate whether a two-bar tumbler will realistically be fast enough to suit your needs.

Hopefully someone actually knowledgeable in mechanical finishing, like our frequent reader Tony Kenton, will offer their thoughts. Although we can't suggest or compare brands or sources on this site (why?), the model numbers you provided will allow interested readers to talk about the technologies employed in those models.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey
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March 31, 2021

thumbs up sign Hey Ted,

Well I ordered the rotary tumbler, with the variable speed.

As you mention, they're supposed to be slower and I also read that won't get into the detailed areas as well.

But I like the idea of being able to vary the size of the barrel, seems like media to parts ratio can be important, and I read that they might be capable of putting a larger radius on the edges, that they might have the edge in a few other situations as well


Now I'll have to pick between the rectangular tank and the circular for the second machine. You mentioned the variable speed might be a good idea, "especially for the non-vibratory tumbling machine". I'm wondering now if it's overkill for the circular bowl, the rectangular tub doesn't offer variable.

I wonder what the advantages/disadvantages of the circular vs the rectangular are in regards to smaller parts, beyond that is, it being easier to locate the parts in the smaller maybe. I think the rectangular tank can be divided into smaller sections which would minimize that disadvantage significantly.

Ted, I really appreciate you responding to my posts.

Billy

Billy Laumen [returning]
- Chicago Illinois
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April 1, 2021

A. FYI the barrel system is good for burnishing and polishing at slow speed, so that was a good choice. If you can live with long time cycles it will do OK on deburring edges, but not as well as vibratory systems. Hope this info helps.

tony kenton
AF Kenton
Hatboro, Pennsylvania
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April 3, 2021

thumbs up sign Thanks for your reply Tony.

It does help, helps me sort out where the rotary tumbler should go in the line up.

Billy Laumen [returning]
- Chicago Illinois
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April 5, 2021

FYI Here is something interesting:
Barrel systems operate at 1 g of force
Vibratory systems at 8 to 10 gs
Centrifugal systems at 18 to 24 gs

tony kenton
AF Kenton
Hatboro, Pennsylvania

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April 6, 2021

Q. That is interesting, maybe that's why barrel systems are the slowest of the three? I wonder if it also makes it gentler. I also wonder about whether higher G's might cause media to "clump", maybe prevent certain action between the media and the parts.


Tony do you think the variable speed is worth having in a vibratory bowel?

Also, do you think something with a large rectangular tank would be to aggressive, might damage smaller delicate parts?

I'm still trying to sort out whether I should look at the bowl or the rectangular tank.

Billy Laumen
- Chicago Illinois
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April 8, 2021

A. Barrel systems are better for burnishing and polishing at cycles of 24 hrs with the proper media non-abrasive. Deburring can be used with a lot of water and compound is important at higher speeds. Tub systems are normally used with longer parts. They are more aggressive over the barrel systems. Bowl systems are better for parts separation. All mass finishing systems are controlled by 3 factors: machine, water/compound, and media. Change one of these and the process changes.

tony kenton
AF Kenton
Hatboro, Pennsylvania

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Previous closely related Q&A's starting in:

2002

Q. I am manufacture of automobiles spare parts & beginner in tumbling process. I have a thrust bearing (top washer) of size 60 mm dia 5mm thickness, hardened at 58-60 degree. Inner hole is 30 mm. When I tempered it at 58-60 points of hardness it becomes gray & oily because I tempered it in oil. Its material is MS sheet. Firstly I take the action of sand blast on it. Is it necessary?

For the purpose of tumbling, I made a tumbling machine but it is not giving the desired shine. The specifications of the self-developed machine are:
- Drum size is 20î dia, 12îheight made of MS sheet 3mm
- Motor is vibrator motor of 1 hp, 2800 rpm 3-phase
- Motor is placed in a vertical pipe passed from the center of the drum.
- Horizontal placement of motor is at the bottom of drum (motor starts where the drum ends)

Are these features correct or not?

In first phase of processing I used ceramic type of media (star, square, triangular, etc mix) with plain water.

I need to know the exact process, the proper structure of the machine, the media size, quantity, timings and the use of compound.

Ahsan Hafeez
J.J. Spares - Lahore, Pakistan
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December 15, 2012

Q. We are manufacturer of screw and want to know the ideal tumbling rpm of our hexagon barrel to provide good finish to the product. Kindly elaborate. Thanks

Rakesh Bajoria
- Kolkata, India
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December 20, 2012

A. To answer your question correctly, we need to know the diameter of the barrel. The media is probably more important than the speed of rotation.

tony kenton
AF Kenton
Hatboro, Pennsylvania
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