SCARA Robot
A SCARA robot is a fast four-axis arm, rigid vertically but compliant horizontally, ideal for high-speed pick-and-place, screwing, and small-parts assembly.
SCARA stands for Selective Compliance Assembly Robot Arm. It has two parallel rotary joints for planar movement, plus a vertical and a rotational axis at the tool, giving four axes. The structure is stiff in the vertical (Z) direction but compliant in the horizontal plane.
That selective compliance makes SCARA robots exceptionally fast and precise for vertical insertion tasks: pick-and-place, small-parts assembly, screwing, and packaging. They typically outpace articulated robots on flat, repetitive XY work.
SCARA robots from Epson, Stäubli, and Yamaha are common on the used market for electronics and consumer-goods lines. Match the SCARA's payload, Z-stroke, and cycle time to your part before buying.