The final step in the plating process is called vibrating finishing, where a tumbling media is used to clean, finish, polish, or de-grease the product.
A tumbling media is any material that is used to impart an altered appearance to another material. It involves an aggressive abrasive process for removing all the unwanted burrs, grinding down sharp edges and providing a polished look to our target material.
Types of Tumbling Media
Tumbling media can be made from four materials:
- Organic compounds
These are the four most common materials for making tumbling media. Other media, such as glass are not as common and are occasionally employed. However, tumbling media comes in a huge variety of shapes and sizes. In order to buy the right tumbling media for your product, you need to take the size, shape, weight, cost, part material, and geometry into account. If you think you are not qualified to do all of this, you should get expert help to assist you with the decision.
Ceramic Tumbling Media
Ceramic Tumbling Media has a relatively high density and is best suited for heavy cutting, grinding, and polishing hard metals such as steel, stainless steel, and titanium. However, for a finer grinding and to produce to a high gloss finish, porcelain can be used. Other benefits of using ceramic media include:
- Highly durable: Ceramic media is excellent at absorbing impact energy. When tumbling rocks, a lot of times a batch turns out rough with fractures and chipping but putting ceramic media in the barrel will keep the stones from hitting each other and also reduce the force with which they hit.
- Wide variety of shapes & sizes: Ceramic media can come in handy when you want a wide range of different sized material in the barrel. The best way to achieve that is by using a variety of rough ceramic media.
- Long-lasting: Ceramic media is highly cost-effective as it can last a very long time.
Ceramic media, though sturdy and durable, can chip away a bit. These little chips can find their way into boreholes and other small areas in the metal parts.
Plastic Tumbling Media
A plastic tumbling media is generally used for soft metals such as aluminum, brass, and zinc or for fibrous materials to smooth their surface. These media usually have a polyester base, but some are also made using urea or formaldehyde.
Plastic media are preferred when we need to produce an even surface as it doesn’t provide a gleamingfinished product. During the finishing process, plastic media is mixed with abrasives such as silica, silicon carbide, aluminum oxide, and zirconium. All these abrasives are used for aggressive grinding, to add some weight, and to grind the metals finely. Plastic media can also provide a lot of benefits in the blasting process like:
- Faster and safer than chemicals
- Reduces energy consumption
- Reduces cleaning time drastically
- Provides superior surfaces for paint
Steel Tumbling Media
Steel media is most recognized for its burnishing capabilities. It is made from hardened carbon and stainless steel and can be used for ball burnishing and polishing of stainless steel. Steel media inflicts pressure on the workpiece, making it easier to remove the defect, improves the pre-plate finish, and reduces porosity on plated parts.
Stainless Steel Tumbling Media also reduces the need to use rust inhibitors, allows for faster finishing times, easy maintenance, and in handling costs. Some other benefits of using stainless steel media are:
- It’s thorough: Steel media polishing is very efficient as you can polish the inside and the outside of any material or workpiece.
- It’s fast: Great levels of shine can be achieved in only 1.5-2 hours of tumbling with steel.
These are different media made from organic compounds, each having a unique application. Carriers such as walnut shell, corn cob, coconut 3P granulate media, zirconia ball, and high-density compounds are a part of this media.
Walnut shell is a hard,fibrous material made from crushing walnuts into pieces. It is incredibly durable, angular, and considered one of the softest abrasives around. These shells are crushed into various sizes to treat different abrasives.
Corn Cob media is made by the middle hardwood of a corn cob. There are a lot of derivatives of this media in the market used in tumbling for removing dust particles, oils and for drying purposes.
Coconut husks are used for grinding and polishing of substances such as gold, silver, titanium, aluminum, and steel. Compared to the walnut shell, it is less angular, but its benefits lie in its durability. Coconut shell is also used for cutting and pre-coloring.
Why Is The Shape Of Tumbling Media Important?
Tumbling media come in different shapes and sizes. You can almost find any shape from cylindrical to star-shaped and pyramids. Selecting the right shape of tumbling media is very important and depends on the shape of the parts being finished.
Most commonly used shape is round, oval and cylindrical as they have fewer chances of chipping off but when finishing complex parts, triangles, arrowheads, and star-shaped media are better, and they can get into small spaces, but they do present with a higher rate of wear and tear and are more susceptible to chipping.
Not only does the shape matters, but the size of the tumbling media also matters. A smaller media can come in contact more easily with the workpiece, but it increases the production time. Meanwhile, large media may produce a comparatively rougher surface, but the process is rapid, and they come in handy in the removal of burs and refining sharp edges.
Things To Keep In Mind When Selecting A Tumbling Media
- What is the required shape and size needed to finish the workpiece?
- Should you mix two tumbling media together or only one will do the job?
- How aggressive does the media need to be? Do you want a fine cut or a coarse cut?
- After completing the tumbling process, how easily will the tumbling media separate from the finished product?