Used Servo Robots for Sale

A servo robot is a Cartesian beam that rides above the injection clamp, reaches into the open mold and sets the part down on a programmed path. Servo motors drive the three main axes, so the hand returns to the same point every cycle. A pneumatic swing cannot do that. The same machine is also called a traverse robot, a cartesian robot or a beam robot. It is not a sprue picker, and it is not an articulated arm standing on the floor. Vertical travel, the demold move out of the tool, and the traverse along the beam are the three moves a basic takeout has to finish inside mold-open time. Payload is the part plus the end-of-arm tool, the cups, the nippers and the hoses on the hand.

Wittmann treats clamp tonnage as a first cut, then checks stroke. A fixed demold axis suits smaller presses, about 20 to 300 tons. A movable demold axis, from about 300 to 1,200 tons, leaves room for a heavier gripper and keeps overall height down. Those frames are still a servo robot. A telescopic vertical arm fits a low ceiling. A single-stage arm is simpler and taller. On a horizontal stroke of about 3 m or more, the drive is often rack and pinion rather than a belt, so the belt cannot stretch and lose position. A pneumatic wrist flips the part through a right angle. A servo wrist adds rotation when the part must turn inside the mold, and an extra rotary axis can take a kilogram or two off the published payload. Sepro prints capacity as parts plus tooling: about 6 kg on a small five-axis Success, 10 kg on the next size, and 15 to 20 kg on a mid-size frame, with horizontal stroke growing in 500 mm steps. Dual arms serve a three-plate tool, one hand for the part and one for the runner.

The unit bolts to the fixed platen or across the tiebars. A sprue picker is the right takeout when only the runner must leave and the part can drop. A six-axis arm is the right machine when the path is insert loading, a box on the floor or a reach the beam cannot make. A five-axis wrist on a Cartesian frame can cover some of those motions and still enter the mold on a straight line, which is faster than an articulated path. Do not hang a traverse on a press whose tie-bar spacing is wider than the beam can clear.

Presses that leave a closed plant often still carry the beam that ran on them. On a used servo robot, home every axis, watch a full traverse and test vacuum at the cups. A pendant that lights up is not a homing cycle. Glazed belts, dry rails or a dry rack will walk the gripper into the steel even when the numbers on the teach box look right. Ask whether the program and the end-of-arm tool come with the arm before you plan the first mold. Record strokes against your tie bars, not against the press it left.