1. What is Tumbling Media?
Any material or substance which is used to give finish or final touch to any part or product is classified as media. Typical media are performed in a rigid molded shape containing a bonding agent. These media work by continual exposure to abrasive particles, as the adhering agent, wears out during the usage of material.
All the tumbling media have some basic functions in common. These are able to provide some support to parts preventing them from mechanical damage, keep parts separate, supply abrasive, improve tumbling action, deburr and also serve as a carrier for the compound.
2. The 9 Benefit of Tumbling Media
- Protect parts to avoid impingements
- Keeps parts separate from one another
- Improves tumbling performance
- Offer Abrasive Element Constantly
- Cleaning, Polishing, Burnishing
- Improve parts surface conditions
- Parts deburring and edge rounding
- Works on cavities, slots, and recesses
- Compound Carrier
3. Considerable Factors for the Selection of Tumbling Media
Some factors that are important and to be considered for selecting tumbling media include the following:
- Choosing the right media type
- Select the proper media size and shape
- Select the media with suitable abrasives
3.1 Choosing the Right Media Type
3.1.1 Ceramic Tumbling Media
For heavy cutting and strong and hard materials such as steel, ceramic media is best for the purpose. Ceramic media is also the best choice if small media is required. Moreover, it is also feasible for deburring of hard burrs. It is also able to support hard and heavy plastic parts in a way much better than a plastic tumbling media. This media is available from a light cut to a heavy cut with a large volume of abrasive material for the fast deburring process.
3.1.2 Porcelain Tumbling Media
Another type of ceramic media is porcelain media. It is generally available in white color and three common shapes of cylindrical, triangular and spherical. The main function of porcelain is to polish the metallic surface and giving a glazed look.
This process is generally completed in two steps. After the product manufacturing, machining process leaves the marks and burrs on it. This can be cleared with ceramic or plastic media. After that, porcelain is used to polish the surface. For soft metals such as aluminum, sphere shape media is the best choice. Cylindrical shaped pins work well for harder materials for example steel.
3.1.3. Plastic Tumbling Media
Plastic tumbling media is used for softer metals such as brass or aluminum. It gives a very smooth finish but produces a matte look with a little shine. Plastic media is 30% lighter weight than ceramic media so it gives less damage. Plastic media does not discolor the metal and peen over the burrs. This type of media tumbling has good performance for parts pre-plating treatment.
3.1.4 Steel Tumbling Media
Steel tumbling media is available in various size and shapes. The typical size is the ball, ballcone, diagonal and oval ball. Because of extremely high density, steel media imposes compressive stress on the metal surface, so parts surface is work-hardened.
In addition, steel tumbling media is non-abrasive media, so it lasts a very long time. The ball burnishing process is associated with steel tumbling media. This process not only leaves a shinier surface but also reduces porosity on metal parts.
3.1.5 Comparison of different types of tumbling media with the functions
|Desired Effect||Degree of Effect||Media Recommend|
Medium to heavy
|Steel or ceramic
Ceramic or plastic
|Radiusing||Light to heavy
|Ceramic or plastic
|Surface roughness||Reduce to lower value
Pre-plate quality on softer alloys
|Plastic or ceramic
Plastic or ceramic
|Surface reflectivity||Brighten or highlight
Best quality, hard alloys
Best quality, soft alloys
Best quality, plastics
|Steel or ceramic
|Clean surfaces||All metals||Steel or ceramic|
|Least operating cost||Varies greatly with grade involved||Steel, ceramic, plastic or wood|
|Fastest processing speed||Overall capabilities of media must be understood||Steel, ceramic, plastic or wood|
3.2 Media Shape and Size
3.2.1 Tumbling Media Shape
Tumbling media manufacturers can make almost all media shapes. But what media to choose must take into account parts size and shape. The feasible sizes are those which will not lodge in the recesses or holes and the shapes must be such that they are able to get access to all the surfaces.
Media should not lodge into parts holes or recesses. To avoid lodging and reaching into an area pyramid, angle stars and cones are best while angle cut cylinders are most effective for passing through holes. Measure the holes or cavities and choose a media that is larger and won’t fit into space or a smaller media that go through holes freely.
You must consider that media constantly reduce its size. When the size goes smaller, it may jam in the parts. So we need to make maximum use of the tumbling media before replacement.
Media should be able to contact all parts surface. Angle cut triangle media can reach edge while angle cut cylinder media cannot. Tri-Star Shape media can contact remote area of parts than triangle shape media.
Media should be easy to screen from parts. Media and parts size shall have a big difference in size so they can be separated with a sieve. If the parts are made from iron, then they can be effectively collected with magnetic separator.
3.2.2 Tumbling Media Size
Large tumbling media will provide a rapid cut and finishing, while smaller media will provide results slower. On the other hand, large tumbling media creates a rough finishing on metals, while smaller media gives a refined surface.
For delicate products use small tumbling media. Large sized tumbling media can be used for hard materials as it may damage the fragile products if used with them. If small size media cut too slowly, we can consider adding 1/3 of big size media.
3.3 Aggressiveness of Media
The requirement for the aggressiveness of the media depends upon the need of a fine vs. coarse cut. Tumbling media aggressiveness can be adjusted by abrasive types, abrasive content, and abrasive mesh grit.
3.3.1 Abrasive types
There are quite a lot of abrasive types available to include in the tumbling media. For example, brown corundum, white corundum, silicon carbide, silica, chromium oxide and also. Among them, silicon carbide is the most aggressive abrasive types known to all. Silica is typically used in plastic media while corundum is commonly used in ceramic media.
3.3.2 Abrasive content
In ceramic deburring media, the typical abrasive content is 20% of weight. The most popular Rosler RS media have the abrasive content around 20%, while for Walther Trowal WXC ceramic deburring media the abrasive content is 50-60%. Some types of tumbling media, for example, fine porcelain media have no abrasive content. In a word, we can increase the media abrasiveness with abrasive content.
3.3.3 Abrasive mesh size
U.S. Mesh Size is defined as the number of openings in one square inch of a screen. We use the term mesh size to quantify the abrasive grit size. The bigger the Mesh size number, the finer grade of the abrasive. For example, 120# mesh corundum abrasive is courser than 320# mesh corundum abrasive. So 120# mesh corundum has more aggressive cutting power.
This article explains the important factors to select tumbling media for mass finishing. Firstly, we need to choose the right media category. Secondly, we choose the proper media size and shape according to the surface of the parts. Last, we select and test the abrasiveness of the tumbling media. To conclude, tumbling media selection in mass finishing require experience and it is a test error based skill.
You are welcome to contact us to utilize our experience to help you find the most suited tumbling media for your parts in a short time.