There are two common kinds of actuators that can be used in spot welding guns – pneumatic actuators and servo actuators. While either kind of actuator will get the job done, there are some advantages to going with a servo actuator.
One of the first advantages is the service life of each kind of actuator. A pneumatic actuator has an acceptable service life if it is properly maintained. However, even with preventative maintenance, manufacturers will get an average of 3 million welds out of a pneumatic actuator. A servo actuator can achieve two to three times that many welds over a lifetime, depending on the type and the distance traveled.
Along with the service life is the maintenance requirements for each actuator. Pneumatic actuators have cylinder rebuilding, air filtration and lubrication maintenance. An electric servo welding actuator has none of that maintenance involved, which cuts down on maintenance costs, saving the manufacturer money.
The servo actuator also has the advantage of faster movement, which reduces the cycle times. Pneumatic systems have to fully open and close during operation, which gives them the “bang-bang” nickname. They also need squeeze time, while servos do not.
One way that pneumatic actuator does win over the servo actuator is in the price. Pneumatic actuators are less expensive. But, when you have to change the pneumatic actuator two to three times in the lifespan of one servo actuator, it works out that the servo is actually the cheaper of the two.
RobotWorx, a certified integrator of robots from FANUC, Motoman and KUKA, has several new and refurbished robot models available that can be used for spot welding and fitted with servo actuators. Servos can be easily program, which means that almost any 6-axis spot welding robot can be retrofitted with servo actuators.