The R 150 DL-2 was an excellent choice for LINK’s new “bi-mobil” hip implant. The implant offers patients a higher degree of mobility by inserting a movable PE joint in the acetabular cup. The PE-joint in turn is clamped to the ball of the hip stem. To minimize friction and prevent premature wear, the inside of the cup requires an extremely smooth surface, which can only be achieved with a high gloss polished finish—something the R 150 DL-2 easily achieves where other surface finishing companies failed.
In addition to viewing work piece impingement as an asset, this type of mass finishing also eliminated the need for ceramic, plastic, and other types of media. The only additives required for such part-on-part finishing are water and the respective compounds.
The applications and benefits of each machine provide a range of part-on-part mass finishing uses for sturdy parts in bulk. Let’s compare their designs.
WTA Rotary Vibrators
Rosler developed special WTA rotary vibrators especially for part-on-part processing. These machines not only allow running the finishing/washing process, but also the subsequent drying stage in one single machine.
As we established in Part 1 of this series, identifying and maintaining an optimal media mix is essential to realizing optimal mass finishing results. Rosler Metal Finishing understands that our equipment must work in tandem with media to provide you with the desired finishing results.
Understanding how your machine, the work pieces it is finishing, and the selected media will interact is key to delivering an optimal finish each cycle. Doing so requires understanding media consumption factors in order to maintain an optimal media mix.
What are the Factors of Media Consumption?
Media consumption and wear rates depend on ten key parameters. These rates change if even one of the parameters below change. Therefore, quoted wear rates and cut rates are relative values only.
Media usage can only be estimated, the actual consumption can only be determined by the end user under exact process conditions.
When it comes to mass finishing, amplitude and frequency require balance and careful consideration. Amplitude is a measure of movement and intensity while frequency refers to the rate of repetition.
The wrong amplitude, for example, if it’s too low, can create a lackluster finishing results and longer processing times. If too high it can cause unnecessary wear and tear on the machine.
Creating Vibratory Energy
Whether rotary or tub style, mass finishing vibrators always include these two key components; a work bowl containing the finishing media and the work pieces. Firmly attached to this work bowl is a vibratory drive system generating the energy to put the mass of media and work pieces in motion. The work bowl with attached vibratory drive system sits on a number of coil springs – in some cases on air cushions – which in turn sit on a machine base. The springs, respectively, air cushions allow the work bowl to “free float” up and down within a certain distance.
The force from the vibratory drive system puts the mass of finishing media and work pieces contained in the work bowl in motion. Depending on the type of finishing machine this force is generated by vibratory motors or electric motors driving a shaft with one or multiple imbalance units attached to it.
Imbalance units are made up of a rotating shaft with out-of-balance counterweights at each end of the shaft. Due to its imbalance, the rotating shaft causes an intensive wobbling effect.
Common drive systems in vibratory bowls and tubs include foot motors for small tub vibrators, flange motors for rotary vibrators, and multiple imbalance units with electric drives for large tub vibrators.
Buying Mass Finishing equipment, as with all investments, can be a bit overwhelming at first. There will surely be a number of suppliers and machine types available to you. In order to ensure you get the best value for your money we recommend you consider the following when purchasing a rotary vibratory machine:
Movement– Appearances can be deceiving, don’t be fooled into thinking all machines are the same just because the look similar. Always test the machine and its processing ability before you buy! Test its amplitude, see how regular the movement is, is it consistently driving the same way?
Strength and durability – Check how heavy the machine is, usually you’ll find something costs less because it is made of cheaper and lighter materials.
Vibratory finishing systems are best known for treating large volumes of mass produced parts. However, thanks to a variety of new, innovative equipment designs, they are increasingly utilized for finishing single work pieces with highly complex geometries.
An excellent example of this new equipment design is Rosler’s model R150/2 DL. A rotary vibrator without an inner dome, this unique finishing process allows for work pieces to be bolted to the vibratory processing bowl.