Advantages to Breaking-in Your Bearings
There are many advantages in conducting a proper break-in procedure for lubricated bearings. Here are a few:
- A proper break-in procedure will:
- Smooth (polish) the raceways regardless of lubrication type
- Reduce the overall operating temperature for an extended period of time
- Extend bearing maintenance cycles
- 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 heat present. The spindle temperature should homogenize before increasing the RPM.
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.
Make sure the oil pump/jet pressure is initiated and running before starting the application.
Why is Breaking In Your Bearings Important?
For grease lubricated bearings, the break-in procedure is as important for the grease placement as it is for the bearing races.
Proper greasing will place the grease between the balls and the raceway(s). Because of this initial grease placement, excessive friction and resistance will cause a mild temperature increase during the break-in procedure, don’t be alarmed by this.
The break-in procedure will make sure the grease is settled into the proper place and will polish the raceway.
Benefits of Properly Placing Grease
Avoiding ‘grease fling’ by properly placing grease is one benefit from the break-in procedure. But you will also achieve a longer lifespan of the precision bearing as well.
Other major benefits are:
- Optimizing max speeds (RPM)
- Better grease performance
- Reduction in the overall operating temperature
- Extending the time between bearing maintenance cycles
- Consistency and reliability of the bearing system increases
Two Steps for Breaking in Your Precision Bearings
We have two steps when it comes to breaking in your precision bearings; short intervals first, then continuous running.
When breaking in your precision bearings always follow these two rules:
- Start out at a much lower speed (RPM) than the application requires
- Wait for the temperature to homogenize before increasing the speed (RPM)
Step One: Short Intervals
Bring the spindle up to speed in short intervals that range from just a fraction to the full nominal speed.
Achieve the speed within 20 seconds and then maintain the speed for approximately 1 minute.
Here’s an example of what a short interval cycle looks like:
- Five cycles of 1 minute each at 33% of max RPM
- Five cycles of 1 minute each at 66% of max RPM
- Five cycles of 1 minute each at 100% of max RPM
**All cycles should have a 2 minute rest period between the short runs.**
Step Two: Continuous Running
The continuous running cycle operates the spindle at nominal or max nominal speed for approximately 30 minutes. Don’t apply any external loads to the spindle during this time.
Here’s an example of what a continuous running cycle looks like:
- Two cycles 30 minutes each at nominal or max nominal operating speed
- Five minutes of rest between each cycle
I. At any time during the run in, the procedure should be stopped if the spindle rises above ~60°C [140°F]. Make sure to take the location of the temperature sensor 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 contact our onsite mechanical engineers for technical support.
II. The procedure should be stopped if excessive noise or vibration occurs at any time. This characteristic is relative per a specific application, but is a direct value for bearing performance. If one’s specific parameters are unclear, please contact our onsite mechanical engineers 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.