Here is a recommended best practice for starting up a robot in cold environments:

Universal Robots joints use strain wave gear technology which are sealed, self-contained, and self-lubricated for the life of the product (no need to exchange or add grease). During normal operation, the lubrication gets naturally recirculated and distributed around the gears and bearings to keep the mechanical systems properly lubricated.

Temperature has an impact on the grease viscosity and gears friction values, Universal Robots recommend to power on the robot, and do slow movements until it reaches internal operating temperature before reaching higher speeds. 

Robot cannot operate with high speed if the joints has not reached internal operating temperature. 

Q/A: What can be considered cold environments and what operating temperature?

The robot can operate in temperatures between 0 and 50 °C. However, Universal Robots consider the internal operating temperature for 35°C. Every temperature that brings the internal operating temperature below 35 °C can be considered a cold environment, and will need to follow the warm-up steps below:  

Q/A: If my robot does small rotations on the joints shall I do this start up? 

Yes, if the rotation of all joints in general make small degrees of rotation only (e.g.: only rotates 25 degrees at all times), then it is a best practice to do the start up guideline below once every two months. This allows the other regions of the bearings to receive auto lubricant lube equally.

Q/A: What is considered internal operating temperature?

Universal Robots consider the internal operating temperature for 35°C but since this can be very hard to obtain during this process and that every robot behaves differently, create a program that gradually increases the speed without going into protective stop.

We recommend at least 21°C internal joint temperature should be reached before top speed can be achieved.

This might not work for all robot and some might need to reach higher internal temperature. Internal joint temperature can be seen in the log tab:

General guidelines for starting up robots that are operating cold environments:

1. Bring robot to room temperature before powering on (if stored in a colder environment). 
2. Brake release- If brake release isn’t ready, set the robot to Back Drive and then manually exercise joints slowly.
3. Exercise all joints slowly in freedrive, one-by-one, without any payload and tool installed.
4. Create a program that exercises the robot joints slowly and continuously for 20 minutes at least.  
5. Limit the output speed to approx. 10 deg/s with standard acceleration. Lower speeds are more effective. If possible slowly raise the speed without entering protective stop until maximum speed can be achieved.  
6. Keep the output rotation angle for each joint as large as possible during the warm-up process
7. Continue operating the robot arm with lower speed until internal operating temperature has been reached.