The affect factors to Light Duty Positioner

You really need to make sure the life of the light welding postioner. Ultimately it will be affected by:

effective payload 

the speed of motion 

duty cycle of various payloads 

environmental contamination 

the sizes of the components selected 

Light Duty Positioner is important to calculate the life for the weakest link, for example a rodded electric cylinder might have a very light payload to move (and seemingly a very long life) but may be encountering a pressing application and significant forces that would limit the ballscrew life. The alternate might be an HD actuator moving a very heavy payload but at a very slow speed with almost no axial force. The weakest link in one application might be the thrust bearings or the screw (see ballscrew life standards ISO-3408-5) and in the other it might be the linear square rail bearings.