There are two basic types of assembly robots: four axis SCARA robots and six axis articulated robots. The term “SCARA” stands for “Selective Compliance Articulated Robot Arm”. This refers to the fact that a SCARA’s arm segments, or links, are compliant, that is, they can move freely, but only in a single geometrical plane.
The first two links of a SCARA swivel left and right in the horizontal plane. The third link consists of a metal rod called a quill, which holds the robot’s end effectors, such as a gripper. The quill moves up and down in the vertical plane and rotates around its vertical axis, but can not tilt at an angle.
This unique design gives four-axis SCARAs a high degree of rigidity, which in turn allows them to move very fast and with high repeatability. In packaging applications, four axis SCARAs excel at high-speed pick and place and other material handling tasks.
Six-axis articulated robots have two more joints than four-axis SCARAs and, as a result, more freedom of movement. The first link swivels in the horizontal plane like a SCARA, while the second two link move in the vertical plane, six-axis articulated robots have a ‘forearm’ and two ‘wrist’ joints, which let them perform the same types of movements that a human forearm and wrist are capable of.
The additional joints of six-axis articulated robots mean that they pick up a part no matter how it is oriented off the horizontal plane, and then insert it into a package that may require a special angle of approach. They can also perform many other operations that might otherwise call for dexterity of a human operator.
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