What is a Precision Ball Screw and Why Should You Know All About Them?

In technical terms, a ball screw is described as a linear actuator that serves the purpose of translating rotational motion to linear motion in a way that creates minimal friction.

As any ball screw manufacturer will no doubt confirm, this basic summary doesn’t begin to describe the huge variety of applications and options that are possible with a ball screw, so here are some more insights to further your learning and appreciation of this important engineering ally.

A wide range of applications

The ball screw was invented back in 1929 and the patent that was was filed by the inventor Rudolph G. Boehm titled his creation as an antifriction nut.

Since that day, a wide range of applications has been discovered for ball screws and variations from that original design have also widened the horizons for this vital component, including the threadless ball screw, for instance, which is specifically designed to eliminate backlash and loading caused by preload nuts.

You will find ball screws used in the aerospace industry to move control surfaces and a common use in the automotive industry is in power steering as a way of transferring rotary motion to axial motion in the steering rack.

Certain machine tools also rely heavily on ball screws and high precision ball screws also feature predominantly in semiconductor manufacturing.

Here is a look at some of the different ball screws and their uses.

High-load ball screws

These are considered ideal for use in large fabrication machines that are designed for metal fabrication, injection molding, and pressing.

They have the ability to heavy loads in either a horizontal or vertical direction with a high degree of accuracy as well as safety.

As with many ball screws, high-load ball screws are adaptable and can be customized in a way that meets your specific requirements.

Precision rolled ball screws

The ball screws are suggested as a solution if you are looking for a structure that delivers smooth motion.

Another notable feature with this type of ball screw is the high level of positional accuracy that it is able to provide.

This type of ball screw is intended to deliver the manufacturing efficiency of rolled processes. The ball nuts can be manufactured with either one or two ball return systems and they are a good choice if you are looking for a solution that is compatible with high speed, high load, and high-temperature applications.

Miniature metric

If you are looking for a cost-effective solution that is capable of performing in small spaces you might that miniature metric precision ball screws fit the bill.

You often find these ball screws being used in semiconductor and laboratory applications.

Choosing the right characteristic

The different ball screws listed are just a flavor of the options available and one of the key questions that you need to consider when trying to select the right product is what key characteristics a specific ball screw has to have if it is to meet your demands and offer a decent length of service.

A good starting point would be to ask your chosen manufacturer to confirm that high-quality steel has been used in the manufacture of the ball screw, as this is essential to longevity and performance.

Steel production technology has reached a point where the volume and size of inclusions can be minimized, and the clue should be in the price being charged, as higher quality steels will naturally cost more.

If you want your ball screw to be made from the best materials available, it might be worth asking whether vacuum-degassed purified alloy steel has been used.

All ball screw components are likely to have been subjected to heat treatment at some point in their manufacture and if the heat treatment is not effective or too shallow it will have a detrimental impact on the life of the ball.

Ask about the heat treatment process to satisfy any questions you might have and to gain assurances that your ball screws are going to perform as expected for a long period of time.

There is a difference between ball screws and lead screws

A fundamental point to keep in mind is the fact that ball screws and lead screws are not interchangeable and you will discover that lead screws offer a solution at a lower cost than ball screws, but the tradeoff can often be a lower level of performance and durability that you can expect from precision ball screws.

A key difference is that a ball screw has the capacity and required quality to be able to carry much higher loads than their lead counterparts, and you will also enjoy faster speeds and more reliable duty cycles with this option.

If you demand a high level of predictability and performance there is little doubt that ball screws win the argument and justify their higher price tag, all things considered.

Preload explained

You would not be alone if you have slightly struggled to understand what preload is when it is used in the context of precision ball screws.

Ball screws normally demand precision positioning and to achieve that aim the motion components need to be rigid.

The issue is that despite the fact that ball guides and screws have the ability to cope with and carry large loads, there is the inherent problem of backlash and clearance, which is down to the size and fit of the balls in-between the raceways.

Preload is designed to nullify this backlash and increase rigidity at the same time.

There are various ways to achieve this preload for a ball screw system and the suggestion is to choose just the right amount of preload rather than opting for too much, as high preload can cause additional heat inside the carriage, which may reduce the lifespan through extra wear and tear.

Talk to your ball screw manufacturer and they will be able to point you in the right direction and help identify the right solution for your specific requirements.