Actuator support bearings

(1) Re-circulating ball screw system:-
     

The recirculating ball screw system are widely used in NC/CNC  machine where rotary motion of motor is converted to linear motion using lead screw.These are specifically required in slide way.

Advantages:- 

Low friction in ball screws yields high mechanical efficiency compared to alternatives. A typical ball screw may be 90 percent efficient, versus 20 to 25 percent efficiency of an Acme lead screw of equal size. Lack of sliding friction between the nut and screw lends itself to extended lifespan of the screw assembly (especially in no-backlash systems), reducing downtime for maintenance and parts replacement, while also decreasing demand for lubrication. This, combined with their overall performance benefits and reduced power requirements, may offset the initial costs of using ball screws.

Ball screws may also reduce or eliminate backlash common in lead screw and nut combinations. The balls may be preloaded so that there is no "wiggle" between the ball screw and ball nut. This is particularly desirable in applications where the load on the screw varies quickly, such as machining tools.

Disadvantages:-

Depending upon their lead angle, ball screws can be back-driven due to their low internal friction (i.e., the screw shaft can be driven linearly to rotate the ball nut). They are usually undesirable for hand-fed machine tools, as the stiffness of a servo motor is required to keep the cutter from grabbing the work and self-feeding, that is, where the cutter and workpiece exceed the optimum feedrate and effectively jam or crash together, ruining the cutter and workpiece. Cost is also a major factor as Acme screws are cheaper to manufacture.

(2) Linear motion guideways:-

Linear guideways provides linear motion by re-circulating rolling elements between a profiled rail and a bearing block. The coefficient of friction on a linear guideway is only 1/50 compared to a traditional slide and they are able to take loads in all directions. With these features, a linear guideway can achieve high precision and greatly enhanced moving accuracy. Hiwin Corporation offers multiple linear guideway series, each featuring different options for sizes, loading capabilities, accuracies, and more.