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The SCARA acronym stands for Selective Compliant Assembly Robot Arm or Selective Compliant Articulated Robot Arm.

In general, traditional SCARA’s are 4-axis robot arms, i.e., they can move to any X-Y-Z coordinate within their work envelope. There is a fourth axis of motion which is the wrist rotate (Theta-Z). The ‘X’, ‘Y’ and the ‘Theta-Z’ movements are obtained with three parallel-axis rotary joints. The vertical motion is usually an independent linear axis at the wrist or in the base. SCARA robots are used in assembly operations where the final move to insert the part is a single vertical move. Component insertion into printed circuit boards is an example. This is often called “vertical assembly”.

They are very common in pick-and-place, assembly, and packaging applications. The electronic printed circuit board industry, in particular, use large numbers of SCARAs for placing semiconductor ICs and other components on the circuit boards of computers and related equipment.

By virtue of the SCARA’s parallel-axis joint layout, the arm is slightly compliant in the X-Y direction but rigid in the ‘Z’ direction, hence the term: Selective Compliant. This is advantageous for many types of assembly operations, i.e., inserting a round pin in a round hole without binding.

The second attribute of the SCARA is the jointed two-link arm layout similar to our human arms, hence the often-used term, Articulated. This feature allows the arm to extend into confined areas and then retract or “fold up

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