In many applications, service life is even greater.
The SW Series Actuators from Tol-O-Matic, Hamel, Minn. (tolomatic.com), are based on a compact, maintenance-free design. An eight-pole Nd-Fe-B hollow-core rotor with skewed stator laminations provides low-cogging torque. This reportedly results in force never changing more than ±3.0% over millions of weld cycles. The design offers weld forces to 2,500 lb and peak force of 4,400 lb. The SW servo's "soft-touch" welding and fully programmable weld-gun operation also improve joint quality and reduce cycle times and weld expulsion.
"The new SW Series represents a technological leap in electric servoactuators," explains Dan Cass, the company's business development manager for servoactuators. "Electric servo welding in robotic and fixture applications is rapidly replacing pneumatically operated spot welding." Servo welding also offers environmental advantages, reducing compressed-air leakage, noise, and exhaust contamination, notes Cass.
The device, built on a 4.4-in. face and weighing 31 lb, is suited for robotic, fixture, and handgun welding, as well as pneumatic-cylinder retrofitting. Overall length is <15 in. with a standard 6-in. stroke. It is available in low (325-Vdc) and high-voltage (680-Vdc) models. The actuator requires no water or forced cooling, and has manual override and bumpers for hard-over situations.
Users operate the device through the seventh axis in a robot or with a weld controller. To simplify setup, the actuator supports various feedback options and is compatible with most major robot and weld controllers. In addition, the company's WeldAxis controller supports the SW servo and includes a controller, PLC, and drive for force and repeatability control.