FreeShip- Ceramic Vibratory Media, 5/16"x 5/8", ACTristars, DF, Dense Fast, 15%- (Prompt rebate on orders with 3 or more FreeShip items!)

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Note: This media is intended to be run in a vibratory finisher or some other high energy mass finishing machine. It will not perform well (unless you're very patient) in rotary tumblers.
If you're a novice, be aware that vibratory finishing is as much art as science. That goes for nutshell, ceramic or plastic media, and others. The surface of the parts you're finishing, the part material, the media, the machine you're using, etc, are all variables that must balance. If one variable is not in tune, the high polish you're after might elude you. Expect a certain amount of experimentation.

The specs for this ceramic vibratory media:
Shape: Angle Cut Tristars (ACTR)
Size: 5/16" x 5/8" (thickness and length of one side of triangle)
Cut (aggressiveness): Dense Very Fast Cutting
Color: Brown
Condition: 15% worn, This is "pre-broken-in" media which has been used and has abrasive particles exposed. No additional break-in is needed. It can be used to cut parts when received. This is the fastest cutting ceramic media I know of. I don't know the formula but I would guess the abrasive particle size is larger than FC, for example. I would also expect that the ceramic matrix wears faster than FC, exposing more sharp abrasive particles at a faster rate than FC. It still has most of it's cutting life ahead. See cutting comments at the top of an FC or a UFX media for comparisons.

Note: "DF" media is the fastest cutting media known to me. There is an aspect of it that I wasn't aware of until a few weeks ago. It is porous all the way through, not just the surface. And if they are the larger pieces they will soak up and hold water, taking a long time to dry at room temps. When I stopped using vibratory media I cleaned it by running water in the bowl with soap (and no parts). When it looked clean, I flushed it further with clean water running in (with vibrator running) and pumping out the used soap solution until no soap bubbles remained. I drained the free water and dumped the media spread out on towels, changing the towels every few days until the media appeared to be dry (they were lighter brown). Then I weighed and packed the media into zip lock bags and boxed them.
Later, when I pulled a bag out I saw moisture on the inside of the bag. It turned out not all of them were completely dry. I put the media in a 160 F oven. After a couple days, it looked different, it was a very light brown and some of it had whitish areas. When I re-dampened it, it looked exactly like it was when moist: a rich dark brown with no whitish areas. The whitish stains are vibratory compound along with a little bit of borax that I like to add, (which seems to speed up the cutting action further) that remained on the outer porous surface in splotches. It had no effect on the very fast cutting action of the media (I tested some).
Some of the pictures of the "DF" media were taken when I first bagged them, which means they still had some moisture in them and are thus a darker brown than you will see if you purchase some totally dry ones that will be very light brown with whitish areas. There are some bags that had pictures taken later that have mixed states of dryness. These variances in color are all due to moisture content.
People like to see that what they purchase matches what's seen in the pictures. If it bothers you that these are a lighter color, do this: simply moisten them. That's the color they will be when you run them in your vibratory finisher.

This ceramic media was purchased about 7 years ago (there's no shelf life, it stays "fresh" indefinitely). It was purchased from a supplier who sold only high quality vibratory media made in the US, not China. They are still around and still sell ceramic media that is: "American Made Since 1972". A lot of what you see today on ebay or amazon is imported and there are a lot of ways to make ceramic or plastic media cheaper. The main way is to use less abrasive content since that's the most expensive ingredient in ceramic media.
The ceramic media we have was mostly for an initial heavy cutting, then to medium cutting, then to polishing of small titanium "chunks" consisting of disks, rods, and irregularly shaped forged pieces. We also used it for rocks and minerals in sizes from 1 to 2 inches up to 8 inches in the same heavy cutting to polishing steps of the titanium.
Ceramic media is just one type of media that can be used in vibratory finishing. Ceramic media probably holds first place in media used if you include industrial usage. Other medias are exotic "ceramic" media made with higher temperatures, stainless steel and steel shaped media, hard nut shells (usually walnut) charged with a cutting or polishing compound, and corn cob or other soft media carriers. Simply do a google search on the phrase "ceramic vibratory media" and you will come up with many suppliers and manufacturers of ceramic and other types of vibratory media, as well as educational info on the codes for ceramic types, and ceramic shapes ("ACT" = Angle Cut Triangles, "ACC" = Angle Cut Cylinders, "ACE" = Angle Cut Ellipse, etc.)
The titanium pieces we were finishing required some heavy duty media because of titanium's hardness and toughness. Most types of rocks we finished were igneous or metamorphic, harder and tougher than titanium. So, 90% of the media we have is ceramic media, and a lot of that is the very heavy cutting "DF" media.

Here is a supplier who sells ceramic and plastic media and gives their code types with descriptions (unfortunately, code names vary from supplier to supplier):
http://vibratoryfinishers.com/tumblingmedia.htm
Below is a good site for viewing photographs of actual media and doing visual comparisons. Click on "Tumbling Media" and the type of media you want to see. Of course these pictures are only of the media this particular company sells. The plastic and ceramic media from other manufacturers can have different code abbreviations and will look differently. And even the exact same media code from the same supplier can vary in color, because what they buy from their manufacturer depends on the materials the manufacturer has and how closely they stick to the same formula (quality control). Here is that link:
https://cmtopline.com/

The "cutting" action of ceramic media comes from the abrasive particles that are mixed throughout the ceramic matrix before it gets fired in a kiln and hardened. There are several types of abrasives (aluminum oxide being the main one) and many formulations that vary by clay types, abrasive types, and the temperature the "clay" matrix is fired at in a kiln (to become "ceramic" media).
The variables in types of media are the composition and mesh size of the abrasive particles, the amount of abrasive particles in the ceramic matrix, the type and hardness of the ceramic matrix, the shape of the media, the size of the media, and the weight of the media (heavier media pieces cut faster).
Almost all ceramic media needs a "break-in" period when new. The abrasive particles are not yet exposed because the ceramic matrix (originally clay before firing) is covering them on the outer surface. They need to be run with some loose abrasive grit, or some media which is already broken in. Or they can be run in a vibrator with no additives, just the new media rubbing and hitting against itself. The time it takes to expose the embedded abrasive particles varies with the type of media. Even "porcelain" media which has no abrasive particles needs a break-in period (to become shiny and "glazed" so it will polish).
What that break-in period causes is a certain time that's wasted; non-productive time (wear) on the vibratory machines. Even mixing new, non broken-in media mixed with used, broken-in media in a batch running parts will take more time to finish because only part of the media is cutting (the used media).
So, buying used media that's already "broken in" is actually more economical than buying new media because there's no need for a break-in period. There is no difference in the cutting action of the media as it wears down over time, except that it becomes smaller and it's true that media pieces that are larger are heavier and so hit the parts being finished harder, but you could also argue that in the progression of finishing, you want a smaller impact against the parts, you want a gentler cutting action as the finish becomes smoother. You will need to add more media to keep the mass in the bowl up to a certain height. On a weight basis alone, the cost of new vs used media is exactly the same.
There are a lot of variables in choosing the type of ceramic media at any one stage of finishing your parts. The main factor is the material the parts are made of and the size and shape of your parts. Are they all curves? Or do they have flat places? How large are your parts? Larger parts usually call for larger media size (for several reasons), but if you only have small media, it will do. It will just take a little more time to finish.
Another factor in choosing which media to use is the part final surface you want to achieve. If you want a high polish you will want to use a non-abrasive media or walnut shells charged with a very light cutting/polishing compound (and if the part surfaces start out rough, you'll first need to use 1 or 2 successively finer cutting medias). If you just need a smooth matte surface or if you just need to deburr, you may be able to use just 1 step (depending of the initial condition of the parts). If your "parts" are stone you will probably be wanting a high polish, which will require a sequence of the heaviest cutting media to start with. That will take the longest time and so you will need more of that media than the medium or light cutting media. If you're parts are a soft metal, like aluminum, silver, or gold, you'll need a milder cutting and finer abrasive media, something gentler and lighter weight. Walnut shells, again, may be a good choice.

Ceramic media is designed to run wet, with some exceptions (polishing can sometimes work well dry if the parts are close to a polished state). Running some types of slow cutting medias dry is possible if you alternate dry with wet cycles. Running dry can cause a "glazed" (shiny) media surface. Glazing is only good when polishing (you want porcelain polishing media to be shiny; if not, it won't polish). Cutting action with glazed cutting media is nil. The cure is to run the cutting media alone, wet, and with some fine loose abrasive added.
Some people add a fine loose abrasive with the ceramic media for every batch of parts they cut. The weight of the media acts as a "driver" for the loose abrasive so it will abrade against the parts resulting in more abrasive particles cutting the parts and thus speed up the finishing process. This also has the effect of keeping the ceramic media surface "sharp" and helps prevent glazing on media which is supposed to cut. The flip side is it tends to wear the media down faster. Some people also use non-abrasive porcelain as the "driving" media in concert with the fine loose abrasive abrading the parts, because porcelain media is so long lasting.

Running ceramic cutting media dry that contains abrasive particles that cut part surfaces quickly, creates a fine waste byproduct consisting of metal from the parts and fine ceramic and abrasive particles. When running dry this will become compressed as a layer of grunge against either the parts, media, or both. It will "gunk" up the process until no further cutting is possible. The machine bowl must be run wet so the waste byproduct is mobilized as a loose slurry which doesn't appreciably slow further cutting. In a "closed" system the slurry will still eventually turn to slush, paste, and again, "gunk" up the process. That can be delayed by removing the lid and observing the movement inside the bowl. When it slows down, the addition of a little more water will extend the length of time the finishing process can continue. The goal will be to get the parts to a finished state before having to clean or "de-gunk" the bowl and media. After some experience you will be able to make judgements just by the change in sound of the media moving in the bowl, without having to remove the lid.
There are two main ways of dealing with waste in a wet process: a "closed system" approach, mentioned above, or a "flow-through" approach. Fairly self explanatory, the flow through system feeds a trickle of water (how much depends on the bowl size) through a fitting at the top side of the machine bowl and drains through a fitting on the bottom of the machine bowl.
The closed system approach relies on said observation of the media (visually or by sound). When the slurry is too thick there are several options. Dumping the batch into an external container and flushing it and the inside of the machine bowl clean is the most radical. Alternatives are several. What worked best for me was to make a "wand" of thin pipe with a nozzle to immerse in the running machine bowl and thereby flow fresh water in with one hand. The other hand will hold a similar wand immersed in the bowl sucking water out with a pump. After a time, the thick slurry will be flushed out completely and replaced with clean water. Then more vibratory compound or whatever "soap" you like can be added to the water in the bowl ("just enough" water should be kept; a sign you have way too much is if any at all splashes upward around the center of the "donut" of the bowl).
The method chosen also depends on the size of the vibratory finisher, of course. My method worked great on my 17", 5 gallon finishers and less well on my 10", 3 qt finisher.
The method chosen for dealing with a wet system has side effects. The flow through system greatly discourages the use of vibratory cutting compound which is expensive. A flow through setup used with vibratory compound is like throwing money down the drain (almost literally in this case!). But vibratory compound really works. If you chose a closed wet system, it's use makes sense. About 1 part compound to 64 parts water is a typical ratio. A little vibratory compound added when the movement slows down works better than just a little water. Because of its expense people have tried all kinds of less expensive materials: Murphy's oil soap, borax, oxalic acid, dishwasher detergent+ammonia, etc. I've tried plenty of things myself. Some kind of soap fits the bill nicely, but whatever you use, it's most important to avoid creating foam in the bowl, which slows the cutting process.

Vibratory finishing has been around a long time now. An exact date is difficult to say but it probably began in the mid 1950's and took hold in the 1960's. It uses the same principles as rotary rock tumblers used by hobby rock collectors (popular with kids in the 50's, 60's, and onwards). The weight of the rocks constantly tumbling against each other with abrasive between them through successively finer abrasive stages for several weeks (or months) ended up with highly polished rock specimens.
Vibratory finishing is similar in that it rubs and hits parts together with an abrasive media under constant movement. But the difference is it does so with many times more speed and energy. Vibration is several orders of magnitude higher in energy than with a rotary tumbler. It can be adapted to very fast "cutting" for layers of oxide removal, to deburring, to simple smoothing, to high polishing. The strength of vibration can be varied with relative ease so that one machine can be put to multiple uses. It's used in industry for finishing large castings, or by jewelry makers for light smoothing and polishing of soft metals.

If your goal is heavy cutting you will be needing a fast cutting media. The variables for speed of cutting have been mentioned above. Also the hardness of the ceramic matrix. And the total weight of the media pieces. Of course the machine matters, too. The cutting speed is quite dependant on the energy (intensity of vibration) put out by the machine.
Weight is very important. If the media is heavy it impacts harder against the parts. The weight of the various ceramic media formulations can vary from 60 to 130 lbs per cubic foot. Usually though, there will be a range of weights listed for each type of media (size matters: larger media has more space between pieces than smaller media, so a cubic foot will weigh less for large shapes and heavier for smaller shapes). A particular formulation, for example, will be listed at a weight range of between 65 to 85 lbs/cu ft, or it may be between 90 to 120 lbs/cu ft, etc.
The clay binder used (which becomes the ceramic matrix) and the firing temperature (hardness) will also affect the media's speed of cut, with a softer post fired ceramic matrix wearing away faster and exposing more fresh abrasive particles and therefore cutting faster (the flip side of that being you will have to buy media more often). Ceramic media can vary from 45 rockwell (rockwell is a measure of hardness) to a harder 65 rockwell.
For ceramic media which cuts, abrasive particles are usually in the 80 to 220 mesh range. Finer mesh sizes may be used for light cutting or pre-polishing. The coarser meshes will cut faster than the finer ones (the flip side of that is how smooth the resultant surface is; coarser meshes leave rougher surfaces).
The amount of abrasive in the ceramic matrix also has a great impact on how fast the media will cut. As the percentage of abrasive in a formulation increases so will the cutting speed, although a point is reached where it is no longer practical to increase the percentage due to low physical strength and friability of the media.

As mentioned above, the major abrasive used in ceramic media is aluminum oxide (Al2O3) and is specifically named aluminium(III) oxide.
Aluminum oxide and alumina are chemically the same, Al2O3, but there are different types of aluminum oxide (or "alumina"). The common brown type is "fused aluminum oxide" and is of varying degrees of purity. It is a brown/black color and is used to make tough (fused) "aluminum oxide" crushed abrasive grains and powders.
The other types are "fused white aluminum oxide", "calcined aluminum oxide", or "calcined white alumina" which are all basically the same thing, purified AL2O3. It is produced by taking the more common AlO3 to even higher temperatures to purify the more common Al2O3. What results is the pure "white aluminum oxide" or "white alumina". It is what "Porcelain Ceramic Media" is made of. It is very hard, and non-abrasive.

For some applications that use the dark fused aluminum oxide, metal parts that have been finished by vibratory machines (or any other method) can be "contaminated" by impregnation of particles of fused aluminum oxide which have been forced into the surface of a part. Metal parts made of titanium (which is inert and can be used inside a human body) that have small amounts of fused aluminum oxide particles exposed can cause compatibility problems with human tissue, since fused aluminum oxide is not inert. Other metals that have fused aluminum oxide contamination can cause other problems, for example if they are welded, brazed, or soldered at a contaminated area the joint will be much weaker.
Awareness of the possibility of fused aluminum oxide contamination for sensitive parts can lead to the choice of using a silicon carbide abrasive in the ceramic media. As mentioned above an "SC" (silicon carbide) ceramic media type exists. Silicon carbide ceramic media does not have the contamination problem that fused aluminum oxide has. Blends of silicon carbide particles are used to get a media that cuts relatively fast but also leaves a very smooth surface. In general, if you look at a pile of pure silicon carbide abrasive particles, they will look black/dark gray with variable shininess. If you look at a pile of pure fused aluminum oxide abrasive particles, they will be a variably dark/darker brown. Silicon carbide is definitely a blackish material. Fused aluminum oxide is definitely a dark brownish material. Silicon carbide is slightly harder (mohs 9.5) than fused aluminum oxide (mohs 9.0). Diamond, the hardest material, is mohs 10.

Usually, a part that has gone through an overall cutting process by aggressive heavy cut media, will require a second cutting with a milder media to achieve a smooth, scratch-free surface. This can be accomplished by using either an "MC" or "FC" (Medium Cut and Fast Cut) which, despite the names, I've found to be pretty close together in real world results. Both will achieve a smooth surface with the "FC" cutting somewhat faster than the "MC".
If a polished (or "bright") surface is required for the parts, a so-called "burnishing" ceramic media can be used. This is the "porcelain" media mentioned above that contains only a very hard porcelain ("fused white aluminum oxide") with no abrasive particles at all.
As your ceramic media wears down and becomes smaller, you will need a strategy for dealing with different sizes of the same media. Most people add more of the same media (some that's new and larger than the worn media) into the vibratory bowl with the smaller media. Sooner or later the smaller media becomes so small that it can become "lodged" (stuck) in holes/concavities in your parts.
At that point you will need to pour the media on a screen put over a bucket which allows the small pieces to fall into the bucket. What's left on top of the screen will be larger (but still smaller than new). If you have a "flow through" flushing system this method doesn't work quite as well because you're still keeping some of the smaller media and inevitably, some small pieces you missed will get into the liquid drain openings and clog your flow through set-up.
To be fair that's a universal problem with flow through systems; no matter what sizing method you use, the drain seems to inevitably get clogged with some stray small pieces (sure, screens and other measures can be taken, but seem to always fail, at least in less expensive machines). I was never successful at getting a long term flow through system to work reliably. If not watched regularly, when the drain would get plugged up, the water continues to flow into the bowl and floods it, stopping the cutting action and leaking water through any gaps in the lid/bowl. If you make sure to always use large, relatively new media in a flow through system, it has a better chance at succeeding. But even then media can sometimes contain a weakness and break into smaller parts and bam, there goes your "only large media" strategy and your finisher is vulnerable to getting plugged up once again.
Another strategy is to remove the media when it becomes a certain slightly smaller size and store it. If you finish different sized parts, you can then bring out the smaller media and use it for the smaller sized parts in a smaller sized machine. I've done this and kept about 3 or 4 step sizes of worn, smaller sized media. You have to collect enough of each size to have enough to fill the machine to a certain level, of course.

How full do you fill a vibratory finishing machine's bowl? Not all the way to the top is the generally correct answer. I've read that it should be anywhere from 1/2 full to 3/4+ full. I think 5/8 is a happy medium. With vibratory machines, the first thing that usually goes bad (if you have a thick bowl that doesn't wear too thin too fast) is the bearings in the motor that has off-center weights on its shaft that create the vibrations. Those weights are how you adjust the intensity/energy of the vibration. Usually every machine will have a mechanism for moving those off-center weights towards the center, which decreases vibration and finishing speed, but increases motor/bearing life. If the weights are moved more off-center than where they were when the machine was purchased you'll increase vibratory energy but decrease motor/bearing life. If you're handy you can remove the motor and replace the worn bearings, getting more life out of your machine. Of course if you're not mechanically adept, you can also spend more money but less time, and just replace the whole motor.

Last but not least is Wikipedia, which I use so much. Their article on vibratory finishing, though, is short and very generalized:
{ https://en.wikipedia.org/wiki/Vibratory_finishing } :
"Vibratory Finishing
Vibratory finishing is a type of mass finishing manufacturing process used to deburr, radius, descale, burnish, clean, and brighten a large number of relatively small workpieces.
In this batch-type operation, specially shaped pellets of media and the workpieces are placed into the tub of a vibratory tumbler. The tub of the vibratory tumbler and all of its contents are then vibrated. The vibratory action causes the media to rub against the workpieces which yield the desired result. Depending on the application this can be either a dry or wet process.
Unlike rotary tumbling this process can finish internal features, such as holes. It is also quicker and quieter. The process is performed in an open tub so the operator can easily observe if the required finish has been obtained.
Vibratory tumblers have an action that is similar to filing. An eccentric, rotating weight shakes the tub in a circular path, during which the entire load is lifted up at an angle and then dropped. As the load is falling (but not actually airborne) the tub returns to an upward position, applying an upward and angular force that causes a shearing action where the parts and media rub against each other
Vibratory finishing systems tend to produce a smooth finish because the media essentially laps the parts. Since the load is moving as a unit, very fragile parts are quite safe in the vibrator. There is no tearing action or unequal forces that tend to bend and distort parts. The larger the parts or media are, the faster the cutting action.
The frequency and amplitude of the machine controls the finish of the parts. The frequencies can vary from 900 to 3600 cycles per minute..."
To get to ceramic vibratory media, you have to go to Wikipedia's article on "Mass Finishing":
{ https://en.wikipedia.org/wiki/Mass_finishing } :
"Preformed ceramic media
Ceramic media are manufactured by mixing clay-like materials and water with abrasives, forming the mud into shapes, drying the shapes, and firing them at high temperatures to vitrify the binder. Many of these binders are porcelain-like in nature. Variability in these products occur both with the type of binder used, firing temperatures, the amount, size and type of abrasive grains they contain, and their uniformity of firing. This type of media today is the general workhorse of mass finishing systems and is the type of medium generally used, because of its availability in a variety of shapes and sizes, low cost, and low wear rate."-

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Aug 3, 2019

lexidonis