Most of the machines being manufactured today have only two types of motion, radial motion, and linear motion. Linear motion is usually obtained from machine elements with radial motion. For example, a servo motor is a radial motion element, but when used with a ball screw, it converts radial motion to linear motion. Linear slide products are also linear motion elements. However, they often require radial drive equipment to move. But, not all radial motion equipment is intended to create linear motion. For example, the turntable equipment in a milk bottling plant works only to produce radial motion.
If you want to rotate a load 360 degrees, the classic way is to use a ball bearing. However, if the movement is less than 360 degrees, curved linear rail products can be advantageous. Because the desired number of linear guides can be added to the rail according to the length of the rail used and the load to be carried. This flexibility provides a price advantage by eliminating the need to use very large diameter bearings.
In some special cases, both radial and linear motion may be required in the same plane. That is, the operation can start with radial movement and turn into linear movement, or it can start with linear movement and turn into a radial movement. The use of curved rail products is very common in automotive assembly lines to save space. Please see Hepco Motion, IGUS, and THK curved guide rail videos below.