The bearing retainer also called bearing cage. It keeps the ball or cylinder evenly spaced around the raceway to prevent ball to ball contact and allow higher speeds. To achieve this, the bearing retainers need to have burr-free surface and low Ra value. So the friction force is greatly reduced.
In this article, we discuss the example of brass bearing retainer surface improvement with the vibratory finishing process. This process is cost-effective and time-saving.
1. Parts condition before finishing
Appearance: parts surface with cutting burr which is visible by the naked eye
Shape: Crown type retainer
Process before finishing: machining
The process after finishing: assembling
2. Parts surface requirement
- Remove the burr coming from the machining process
- Reduce surface roughness
- Improve parts surface brightness
3. How we process the parts
|Step||(1) Grinding||(2) Polishing|
|Machine||Vibratory Tub with dividers||Vibratory Tub with dividers|
|Tumbling Speed||50/60HZ (full speed)||50/60HZ (full speed)|
|Chip Type||Plastic Media TET/Cone Middle cutting||Zirconia ball 3-4mm|
|Media to Parts Ratio||One part per compartment||One part per compartment|
|Compound Type||LC-13, PH 8 (mild grinding compound)||HM-3 with HX-0|
|Water Level||Just cover the mass||Just cover the mass|
|Tumble Time||60 min||20 min|
|Notes—||Manually take the parts out of the machine, and rinse them||Manually take the parts out of the machine, and rinse them|
4. Parts condition before and after polishing
The upper part is the one without the tumbling process. And the part below is the one after deburring and polishing. You would clearly see the burr after the cutting process is removed after vibratory tumbling. If you take a close look, the edge is rounded and the surface is smooth.
5. Other considerations
Brass is a soft metal material, so we should prevent parts-on-parts impingement. To increase parts productivity, we can use a trough vibratory tub with separated compartments. This can avoid parts hitting marks.
As soon as we finish the first step (plastic tumbling media process), we can put brass parts to the zirconia ball chamber. As a brass retainer manufacturer, you can prepare two machines. One machine is filled with plastic media and another with zirconia ball.
When you process your parts in the second process, you can deburr the new batch in the first machine. In addition, you don’t bother to change the media. Therefore, you can greatly reduce the downtime and increase productivity.
Because the polishing time is less than the deburring process, so the second machine can be a smaller size.
In this article, we explained an example of brass retainer parts deburring and polishing. It is a big part with the delicate surface.
The content includes the parts initial condition, surface requirement, our process to finish, and also comparison before and after tumbling. This process is simple and repeatable. Yet, it is cost saving and time-saving.
However, the same parts surfaces from different manufacturers may not the same. So we suggest our client send us a real sample to check in our lab. Then we can give our tips on how to get the desired finish with lowest possible cost.