A high-precision ball screw system primarily serves to efficiently convert rotational motion into linear motion. In some cases, this conversion can achieve an extremely high level of precision, accuracy, and repeatability.

 

The ball screws and ball nuts are generally classified according to the manufacturing method of their screw threads. There are two main approaches: one is rolling machining, and the other is precision grinding machining.

 

However, choosing rolled ball screw or ground ball screw depends on specific machine equipment. These practical illustrations, as follows, will be a great help in the choice.

 

Ⅰ. Precision X/Y Positioning Tables

Dimensional inspection tables, with diverse designs, are widely used in manufacturing, inspection, etc. They commonly use a precision-ground ball screw system for accurate positioning. Servomotors drive the precision ground ball screws in both large and small tables. They can achieve higher precision (1 microinch in some cases) and more excellent repeatability.

 

 

Ⅱ. Steppers Used in Lithography Equipment  

Ball screws are also present in step photolithography machines, which have greatly boosted computing power. Photolithography is a microfabrication method that uses light exposure on silicon wafer thin-film substrates to create reactions. To work it, the stepper, operating on a microscale at extremely high degrees of precision, controls the position and location of the light exposure on the wafer.

 

In this stepper, similar to the X/Y positioning stage, the linear motion Ball Screw Drive is paired with a servo-motor and a harmonic gear reducer. Only high-precision ground ball screws, operating smoothly, quietly, and efficiently can achieve high precision and repeatability, meeting the strict repeatability requirements of the wafer exposure process. 

 

 

Ⅲ. Automotive Power Steering

The most common ball screw is in a typical car's power-steering system. Unlike the X/Y table, a car's power-steering system doesn't need as high precision and positional repeatability. When the driver turns the steering wheel, the linear ball screw rotates, moving the ball nut that acts as a piston in the power-steering's pressurized fluid system. The ball nut connects to the Pitman arm through teeth on its bottom. The Pitman arm links the power-steering box to the center link that moves the wheels. The ball-nut motion moves the Pitman arm, controlling the center-link and front-wheel movement.

 

For automotive power-steering applications, sturdy Rolled Ball Screws work well and cost less. Their main job is changing rotary motion in the power-steering piston to linear motion. So, a rolled ball-screw nut is sufficient for this application's required motion transfer and lower-precision positioning.

 

 

If you need assistance in selecting the right ball screw for your application, feel free to consult the professional team at Hojama at any time.