What Are Ball Screws?

Most people know what a screw is, but not everyone realizes that ball screws operate a little differently. These mechanical linear actuators are significantly more complicated. Read on to find out how they work.

What Are Ball Screws?

The first question to answer is, What is a Ball Screw? In simple terms, it’s a tool used to convert rotational movement into linear movement. Each screw is made up of three main components:

• The nut
• The screw, which always features helical grooves
• The balls

There are other different classifications of ball screws and methods for ball return, as well. For now, though, it’s best to stick to the basics.

How Ball Screws Work

All ball screws share the same basic principles. The balls travel through the helical grooves as either the screw or the nut rotates. This produces a continuous, back-and-forth movement, turning the rotational power into more useful linear power.

Once the balls reach the end of the screw, they are routed into the nut’s ball return system. This process allows them to follow a continuous path and produce consistent motion.

Classification of Ball Screws

There are four primary classifications of ball screws, each of which is used for a different set of applications. Screws can be classified based on:

1. Axial play
2. Preload
3. Load accuracy
4. Life/load relationship

Axial play refers to how much a ball nut can be moved in the screw’s axis direction before it begins to rotate either the nut or the screw. Preload is a process that increases stiffness in the ball screw to minimize backlash. Load accuracy refers to how the shaft’s rotational movements get translated into linear movement.

Paying attention to these four traits can help buyers make sure they wind up with the right ball screws to meet their needs. Of course, there are also other characteristics to consider in addition to accuracy, preload, and axial play. Some applications require greater efficiency, for example, although all ball screws can achieve efficiency levels of 90% or greater.

Ball Return Methods

All ball screws need a method for returning the balls from the bottom of the helical grooves back to the top. Some use internal return mechanisms, while others feature external returns. External return tubes are cost-effective and easy to maintain and repair, but they’re not right for every application. Internal return systems are usually found on low lead screws, where their more compact nature creates less noise and vibration and reduces the potential for mounting complications.

Understanding Ball Screw Pricing

Ball screws are almost always more expensive than lead screws. However, they make up for the increased price with much more impressive efficiency and accuracy ratings. Other characteristics that can influence the cost of ball screws include whether they have internal or external ball return systems, what material they are made from, and how precise they are.

Where to Find the Best Ball Screws

The best way to get high-quality ball screws at competitive prices is to find a reputable online dealer. Look for a company that can both manufacture custom ball screws for any application and provide ball screw repairs and maintenance services to ensure the best long-term results.