Initial Startup or Break In Procedure
There are many opinions and thoughts on a proper break in procedure for Oil lubricated bearings. However, there are a few points that are generally accepted:
- A proper break in procedure will:
- Smooth out (similar to polish) the race ways regardless of lubrication type.
- Reduce the overall operating temperature for an extended period of time.
- Increase the bearing/unit service life.
- Increase consistency and reliability of the bearing system.
- Ensure that all lubrication systems are working properly.
- When performing a proper break in procedure, slowly increase the RPM to ensure there is no excessive temperature present. The spindle temperature should homogenize before increasing the RPM.
- A caution when running any application at any time is to be sure the Oil pump/jet pressure is initiated and running prior to the spindle rotating.
- Consider the length of oil feed tubes to avoid insufficient lubrication. The entire delivery system will need to have oil passing through it to ensure there is a small amount of lubrication in the bearing before any rotation occurs.
- As intimated above, the below procedure can be used for either Oil or Grease lubricated bearings.
Bearing Greasing/Lubrication Procedure
For grease lubricated bearings, the break in procedure is as important for the grease placement as it is for the bearing races. Proper greasing ensures that the grease is placed in between the balls within the raceway(s) itself. Because of this, there is excessive friction and resistance that causes mild temperature increases during the break in procedure. A precision bearing break in procedure will ensure the grease is in the proper places as well as smooth out (similar to polish) the races. Proper grease placement while avoiding ‘grease fling’ is vitally important to a long precision bearing life. Benefits include but are not limited to:
- Optimization of maximum RPM
- Optimization of grease performance
- Reduce the overall operating temperature for an extended period of time
- Increase the bearing/unit service life
- Increase consistency and reliability of the bearing system
Example Precision Bearing Break In Procedure
The below precision bearing break in procedure can be used as an example or starting point for a customized break in procedure. A couple of the key aspects are:
- Starting out at a much lower RPM than the application RPM
- Waiting for the temperature to homogenize before increasing the RPM
PDF example of precision bearing break in procedure (seen below).
Precision Bearing Break In Procedure / Grease Run in Procedure
There are 2 overarching steps for the break in procedure
- Short Intervals
- Continuous running
1. Short Intervals
The spindle should be brought up to speed in short intervals whereas the interval speed ranges from a portion to full nominal speed. The respective speed has to be achieved within 20 seconds and should be held for approximately 1 minute. The complete cycle should be set up similar to:
- 5 cycles of 1 minute each at 33% of max RPM
- 5 cycles of 1 minute each at 66% of max RPM
- 5 cycles of 1 minute each at 100% of max RPM
**All cycles should have a 2 minute rest period between the short runs.**
2. Continuous running
For the continuous running cycle, the spindle should be operated at nominal or max nominal speed for approximately 30 minutes. No external loads should be applied to the spindle during this time.
- 2 cycles of 30 minutes each at nominal or max nominal operating speed
- 5 minutes rest period in between and after the cycles
I. At any time during the run in, the procedure should be stopped if the spindle rises above ~60°C [140°F]. The location of the temperature sensor must be taken into account. A temperature sensor on the housing of the spindle will read much cooler than what the bearings are actually running. Please consult product documentation for temperature limits or consult GMN USA engineering for technical support.
II. At any time during the run in, the procedure should be stopped due to excessive noise or vibration. This characteristic is relative per a specific application, but is a direct value for bearing performance. If one’s specific parameters are unclear, please consult GMN USA engineering for technical support.
III. The viscosity and volume of grease fill will have an effect on the break in procedure – i.e. time at each step. Ensure that spindle temperatures homogenize before moving to higher RPM’s. This will be directly related to max temperatures during the break in.