Tumbling Media Selection Guide

tumbling-media-selection-guide

1.  What is Tumbling Media?

Any material or substance used to give a 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 material usage.

All the tumbling media have some basic functions in common.

These can provide some support to parts preventing them from mechanical damage, keep parts separate, supply abrasive, improve tumbling action, deburr, and serve as a carrier for the compound.

2.   The 9 Benefits 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 the deburring of hard burrs.

It can also support hard and heavy plastic parts in a way much better than 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.

ceramic-tumbling-media

Ceramic tumbling media 

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.

porcelain-tumbling-media

Porcelain tumbling media 

This process is generally completed in two steps. After the product manufacturing, the 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 of pre-plating treatment.

plastic-tumbling-media

plastic tumbling media

3.1.4 Steel Tumbling Media

Steel tumbling media is available in various sizes and shapes.

The typical size is the ball, ball cone, diagonal, and oval ball.

Because of extremely high density, steel media imposes compressive stress on the metal surface, making parts surface work-hardened.

steel-tumbling-media-1

Steel tumbling media 

Besides, 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
Deburring Light
Medium to heavy
Steel or ceramic
Ceramic or plastic
Radiusing Light to heavy
Irregular surfaces
Ceramic or plastic
Random shaped
Surface roughness Reduce to lower value
Pre-plate quality on softer alloys
Plastic or ceramic
Plastic or ceramic
Surface reflectivity Brighten or highlight
Top quality, hard alloys
Best quality, soft alloys
Best quality, plastics
Steel or ceramic
Ceramic
Plastic
Wood
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 will not lodge in the recesses or holes and the shapes must be such that they can get access to all the surfaces.

Media should not lodge into parts holes or recesses. To avoid lodging and to reach 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 larger media that won’t fit into space or a smaller media that go through holes freely.

plastic-media-jam-in-the-parts

Plastic media jam in the parts 

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 the edge while angle cut cylinder media cannot.

media-should-contact-all-parts-surface

Media should contact all parts surface

You can easily collect parts from the media. The media and parts size shall have a big difference in size to be separated with a sieve. If the parts are iron material, then they can be effectively collected with a 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 for 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, etc. Among them, silicon carbide is the most aggressive abrasive type 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 specific abrasive content is 20% of the weight.

The most popular Rosler RS media have 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, 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.

4. Conclusion

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 requires experience and test error-based skills.

You are welcome to contact us to utilize our experience to help you find the most suitable tumbling media for your parts in a short time.

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