Despite the developments in linear motion, Phil Burge, communication manager at SKF, argues that standard products are more than suitable for use in the majority of applications

In recent years, manufacturers of linear motion devices – including profile rail guides, slides and actuators – have expended significant technical effort and exhausted marketing budgets in extolling the virtues of products with ever greater levels of performance and precision.

As a result, there has been considerable interest in innovative methods of minimising friction, noise and energy loss, and in finding ways of reducing errors in repeatability, while reaching submicron levels of accuracy. The upshot has been a plethora of design ideas, ranging from caged balls to the adaptation of specialised X and O geometries, gothic arches et al.

While important, these developments have obscured the fact that, in the majority of applications, the performance and reliability of standard linear motion devices is more than adequate. Existing devices provide the levels of performance, accuracy and reliability required by engineers, so they need not be seduced into over specifying, or over spending, on ‘cutting edge’ technology.


Linear motion devices have been used extensively for many years, to position and move parts, work pieces and tooling in single or multiple axes in a wide range of environments – from aviation systems and medical scanners to high speed factory automation lines. They are therefore a proven technology that offers extremely high levels of performance with, in most instances, a long operating life. They are particularly useful in applications where space and weight savings, together with almost silent operation at high speeds, are critical.

With the ability to position even the heaviest loads with exceptional levels of precision and repeatability, standard linear motion devices provide engineers with the opportunity to make considerable improvements in line efficiency and, as a result, boost profitability. Indeed, while they may not be as high profile as some of the latest all singing, all dancing designs, traditional linear motion technologies continue to achieve excellent levels of accuracy, speed and reliability. They enable businesses to realise significant cuts in operating costs, as they require minimal maintenance or manual intervention.

Furthermore, it is becoming increasingly common for manufacturers to combine these components to deliver subassemblies that serve as self-contained units to provide enhanced performance in terms of speed, strength, accuracy and reliability, while reducing machine build time and costs.

Ball screws, for example, have been used for many years, but manufacturers such as SKF have been continuously developing the technology to meet changing market demands. As a result, ball screws continue to be a popular choice in many applications for providing a cost effective combination of reliability, accuracy and robustness. Moreover, the latest versions offer particularly high levels of precision and repeatability, with optimised designs to minimise frictional losses, noise and heat. Advanced materials with excellent mechanical characteristics reduce size and weight, while improving overall performance.

Equally, the latest linear and rotary actuators are capable of high levels of speed, temperature stability and accuracy, with standard devices able to accommodate loads as great as 12kN at accuracies of up to 6µm/1000mm, while achieving speeds of up to 174mm/s and travelling as far as 1500mm. There is now such a wide variety of functionality and capabilities available that the right solution can be found to meet the load and speed requirements of any automation application. Furthermore, a growing range of controls and operating devices is expanding the environments in which conventional linear motion devices can be beneficial.

For example, many standard actuators now feature modular designs that make it easy to interchange critical components such as motors, gears, screws and attachments. This ability to custom-build actuators easily and cost effectively from standard parts makes the technology suitable for a diverse array of applications, including many where the use of electromechanical technology has previously been limited. It can also help to make linear motion systems easier to install and maintain, often with compact dimensions that allow the space required for automation systems to be minimised.

A proven technology

Offering strong load carrying capacities, fast duty cycles and quiet movement, traditional linear motion devices, such as linear actuators, provide a viable alternative to some of the latest novel designs, especially in challenging industrial environments. This proven technology is cost effective, energy efficient and safe.

In common with linear actuators, traditional electromechanical rotary actuators are also compact in size but able to produce high torque. Capable of withstanding heavy loads, they can be used as an integral load bearing element of an automation system. To save costs, a range of standard rotary actuators is available in a variety of sizes to suit most applications.

The need for increasing automation and productivity – especially in technically demanding applications that rely heavily on extremes of accuracy, speed and reliability – is ever more critical as companies fight to succeed in today’s competitive marketplace. In many applications, the key to achieving this success is through the use of proven linear motion technology that delivers the results needed without expensive and specialised development.

The recent developments in linear motion technology mean that there is now a product to meet the demands of almost any application, whether it is a ready to install unit, or a combination of standardised components that can be used to create a bespoke system.

It is easy to see why there is not always a need for over complex and expensive innovations in the creation of linear motion solutions that provide accuracy and reliability. This, in turn, pays a considerable contribution to improving productivity and, ultimately, profitability.