Frequently Asked Questions
Please contact us with your deburring questions.
You can click on any of the questions below to see the answers. If you don’t see the question you need answered, we encourage you to contact us by phone at 800-827-1333 or email at firstname.lastname@example.org.
How do I select a machine?
All vibratory machines are sold based on a volumetric measurement of the tank. Tumbling barrels are also sold based on their size. Most mass finishing is done in vibratory deburring machines. Tumbling barrels are used for small parts like jewelry and medical device manufacturing. They work well on many other very small parts. It is easy to retrieve small parts from a tumbling barrel using a separation screen. They also work great to polish parts because the media slides by the part as opposed to the more aggressive action of a vibratory machine.
So in selecting a machine you need a tank that will fit the biggest part you want to run and /or a machine that will handle the volume of parts that need to be process in a given period of time. The tank needs to be big enough for the part to freely turn with out getting stuck. We make a full line of both rectangle vibratory tanks, round vibratory bowls and tumbling barrels. The rectangle tanks lend themselves to odd or big parts. The bowls are better for small parts or in cases where you want to change media for doing different jobs. The media changes would be cheaper in a small machine because there is less media required to fill it.
How does the process work?
The process is the same regardless if you are de-burring steel, aluminum or any other material. The media in the tank is usually either plastic or ceramic. Plastic media is used on aluminum and ceramic is used on steel. The media has aluminum oxide or other abrasives imbedded in it all the way through. As the media is turning in the machine the base material is wearing down slowly and exposing new abrasive on the surface of the media. As the media goes back and forth across the part it deburrs it. At the same time water and compound (soap) is being circulated through the machine to keep the surface of the media clean. Very similar to having water running over a grinding wheel to keep the surface clean and the pours of the wheel open. If the water is not kept clean or no compound is used, the media becomes glazer over and it’s ability to de-burr greatly reduced. So it is important to clean the water in your machine often and use compound for the best results.
What kind of media do I need?
When choosing media you will need to choose the type, size & shape and the level of abrasiveness. Below are some basics to begin with.
We are happy to help you find the right media for your job. This is our specialty. C & M has experienced people to talk with you. We also offer free test runs on your parts in our laboratory to ensure you are using the best media for your application.
- Ceramic is most common used for steel and stainless steel.
- Plastic is used for aluminum and soft metals.
Size & Shape:
The size and shape will be determined by the size of any holes or slots in your parts. You will want to pick a media that will get into the smallest places of your parts but not get lodged. Media lodging is the main thing you want to avoid regardless of the material you are doing. There is something called the 70% rule. Meaning when selecting media, it should be at least 70% the size of any hole or slot. That way two pieces cannot get side by side and get stuck in the part. Also the media can be used for a substantial time before lodging becomes a problem.
Level of Abrasivness:
This is determined largely by the hardness of the material, the amount of deburring and the type of finish you want on your product. We have extensive description the formulations on our tumbling media page.
If you are deburring aluminum such as 6061alloy, plastic media in the VF-X formulation is the most common media used for this. Some aluminum alloys such as 7075 or 2024 are hard enough that they can be de-burred in ceramic media also.
If you are deburring steel or stainless, ceramic media in the VF-SF formulation is the most common media used.
Plastic parts can also be de-burred in our machines using ceramic media. Plastics have high abrasion resistance, so you need to be aggressive to get good burr removal. Plastic parts will have a matte finished when done. A second step in porcelain media to bring the plastic part back up to a polished surface.
For polishing steel, stainless, aluminum and plastic parts, porcelain media is the most common media used. Any shape of porcelain can be used. One of the most common polish media used is a 3/16-3/8 angle cut cylinder. The theory is that a cylinder has more surface contact with the part than other shapes. If you are polishing aluminum, you need to use balls. The porcelain media is very hard and if you use other shapes like cylinders or triangles the edge of the media will nick the part. The most common ball used is 4, 5 or 6 mm porcelain. To polish brass, dry media such as walnut shells or corncob with rouge coating is the most common. Dry media is not usually used on other materials because the run times will be too long. Plain cob will sometimes be used to dry parts. Most often polishing will require two steps, the first step, called the “cut down” will remove machining marks and imperfections in the part. This will be done with gray ceramic media for steel or green plastic for aluminum. Then there will be a media change, to porcelain for the second step. A special compound will be used for the polishing step.
How long does media last?
The media wears down slowly. The general rule is the media loss will be ½ % per hour of operation. This can vary depending on how aggressive the media is and the size of the media. The aggressiveness of the media is referred to as the formulation. All media comes in different levels of aggressiveness and many different shapes and sizes.
The faster the media cuts, the faster it will wear. In general the larger it is, the better burr removal you will have. The smaller media will gives a better finish, but it will take more time in the machine. Also small media will tend to cause more media lodging issues. Selecting a larger media has the benefit of not lodging in the parts as it breaks down.
Most all media is the same cost from ½” size or larger. Small media can go up in cost and can gets incrementally more expensive the smaller it gets. This is because it is more labor intensive for the manufacturer to make small media.
The actual cost for plastic and ceramic is similar even though the purchase price for plastic will generally be more expensive than ceramic. This is because plastic media even though it wears faster than ceramic, is also more light weight so takes less to fill the tank. Ceramic wears more slowly than plastic and is cheaper, but will require more pounds to fill the machine.
Overall the media cost is low compared to sandpaper, Scotch-Brite pads or other de burring tools. The key is to have the correct media for the job and to have the machine full of parts. The wear rate of the media is the same if the machine has one part in it or is all the way full of parts.
Media wear is a good thing. As it wears it is constantly exposing more abrasive surface on the media which creates an increase in the deburring process rather than a decline. Media only needs to be replaced when the size becomes so small that it begins to lodge in the parts you are processing. The media should be porous and dull on the surface. If the surface is shiny it is not breaking down and not giving you good burr removal. If your media is glazed over it should be replaced.
What are compounds?
Deburring or burnishing compounds are a liquid concentrate similar to soap which is mixed with water and used in the machine during the deburring process. The water and compound solution play an important role in the deburring process. They lubricate the media and keep the surface of the media clean. Another purpose of the compound and the water is to maintain the suspension of the soils, machining oils or metal removed from the parts and media. Otherwise, the cutting oils on the parts and the material will clog the surface of the media and reduce its action. Compounds can also react chemically with the parts being worked to affect finish and influence cycle times. Some operators of vibratory machines try using water soluble oil in the machines as a rust inhibitor. This should NEVER be used. The oil will clog the pores of the media and prevent it from deburring. There is a compound with a rust inhibitor in it that should be used for this purpose and it will not leave a film on your parts.
There are general purpose compounds used on all metals like our VF 77. There are also compounds that contain rust inhibitors for steel like our VF 100. Polishing compounds are either acidic VF 150 or alkaline VF 103 depending on the alloy you are burnishing
It is sold in five gallon containers and 55 gallon drums. Mixing concentration is one to four ounces of compound to one gallon of water.
The compound mixture can be circulated through the machine with a pail and submersible pump or as with tumbling barrels and small bench top bowls run as a batch to be refilled with each load. Water systems can also be run as a flow through, where the water and compound are mixed with a mixing valve. The water is fed into the machine slowly, then allowed to drain directly to the sewer. This way the water and compound is always clean. There needs to be traps in your drain system to use this type water/compound process. The trap will segregate the solids from the water and keep it out of the sewer system. If you are circulating or running a batch type system it is very important to change the fluid often. The solution should be changed at least every 4 hours of machine operation or in a batch system every time the parts are finished.
How long do I have to run my parts?
Most parts will need to have a uniform appearance as well as an edge break. Often times there are machining marks in the surface that need to be removed. To remove machine marks on the surface, it takes longer than to just break an edge. On aluminum parts run time can be 45 minutes to an hour and a half. Stainless steel and carbon steel run times can be 45 minutes to two hours or more. These are rough guidelines and actual time may vary. Polishing parts in porcelain or steel media will usually come to a nice shine in about 20 minutes to one hour.
How many parts can I run at a time?
There is no hard and fast rules about how many parts can be placed in the machine at one time. You can usually have more steel parts in the machine than aluminum because of part on part contact. The machines can easily handle the load; it is a mater of the part on part contact damaging each other. The media likes to get between the parts and keep them separated. The exact ratio of parts to media is usually a mater of trial and error and will vary some depending on the part configuration. If you took a 5-gallon pail and filled it half way with parts, that would be a comfortable load for our 3 cubic foot machine. For the 6.5 cubic foot machine, it would hold about three times the parts. You want your parts to be surrounded by the media and not banging into each other.
To Learn More
This just a rough overview of the de-burring process. There are no hard and fast rules in this industry. Many companies will develop their own process for particular parts. It may also be that you are trying to achieve a certain look to your part that will make it unique in your industry. There are numerous medias available for doing limitless operations in vibratory machines and tumbling barrels. If you would like to educated yourself further, the best book on the market is by LaRoux Gillespie It is called Mass Finishing Handbook ISBN-13(978-0-8311)3257-6. To order it, call 724 282-6210. It has a lot of very detailed information. We are also available to answer any questions. Give us a call at 800 827-1333, from eight to five pacific time.