Hello @tanu, welcome to the Universal Robots community!
It is not possible to activate the joint brakes through programming.
However, the maximum torque of each of the joints is not strictly the limit of the possible torque that can be applied with an automatic screwdriver and withstood by the robot - it could be higher or lower, depending on several factors that include:
- Tool mounting
- Robot programming
- Safety settings
- Robot poses
- Payload
- Others not directly related with the robot, e.g., the tightening setup in the controller of the screwdriver that determines the strategy, torque, speed, angle, etc.
Screwdriving applications beyond 60 Nm usually require careful consideration of all the above factors, so I would encourage you to contact your Universal Robot distributor or a certified system integrator to help you achieve the require torque ensuring best possible performance and longest working life for the robot.
Some of the key points are:
- Mount the automatic screwdriver or nut runner to the tool output flange of the robot in such way that the lever arm is maximized, thus the force required from the robot is minimized in order to maintain its position during the process; and avoid that the tightening axis is aligned, parallel or close to parallel with the Wrist 3 of the robot.
- Define accurately the tool position, and the weight and center of gravity of the payload
- Use the least restricted tool force limit value that the risk assessment permits.
- Use the Screwdriving command in PolyScope with the option to Follow the screw using Force if the robot needs to move during the tightening process; or make sure that the robot is standing still before running the screwdriver - is_steady() == True