Linear motion components - Things worth knowing about guides, screw drives and more

Linear motion components allow linearly guided motions and move loads directly along a linear path. This is an important part of industrial automation.

Linear motion components include linear guides, linear actuators, and other components that allow linear motion.

Some of our most popular products are:

• Linear guides
• Linear motors
• Linear drives
• Linear positioning systems

Read more about available complete solutions for implementing linear motion here.

What is a linear guide?

A linear guide is a mechanical component used to guide a moving part in a straight (linear) motion.

The basic components of a linear guide are a guide profile and a linear bearing. Linear guides can be used to pick up a load and move or hold it in a guided manner, e. g. to control a machine.

Linear guides are used in many different industries, such as in robotics, aerospace, 3D printing, medical technology and electronics. They do not have their own drive and are often used in applications that require precise and reliable motion. They are robust, durable and can achieve high precision.

In general, linear guides can be grouped into profile rail guides and guiding by means of a linear shaft (linear axis).

Linear guide with recirculating rolling elements

One of the most common variants of these linear guides are linear guides with ball recirculation. In these linear guides, balls located in a recirculating ball guide provide precise linear motion.

For example, on a profile rail guide, they consist of a guide carriage travelling on a guide rail with specially formed ball tracks, which act as a guide for the embedded rolling elements.

Practitioners distinguish two designs for the rolling elements embedded in the recirculating ball drive. The guide can be designed with plastic bodies inserted between the rolling elements as a spacer and damping element or with rolling elements without such elements.

The damping elements are intended to reduce sound reduction and to promote quieter circulation of the rolling elements.

What is a linear motor?

Linear motors are specially designed motors that generate linear motion. This movement can be in a straight line, but also on a cam track. In addition to speed and dynamics, their great advantage is that they can move loads directly along a linear rail without requiring additional gears, belts or other mechanical transfer elements.  

Linear motors are used in many other industrial and manufacturing industries. They permit high travel speeds, are reliable, fast, robust and achieve high positioning accuracy.

What is a single-axis actuator (LX and RS)?

An actuator is a device that converts a physical input (such as an electrical voltage) into a mechanical action that then fulfills a specific purpose. Actuators are an important component of automation technology and can, for example, be used to drive a machine, to generate mechanical movements or to control valves and flaps. They can be controlled directly or indirectly and fulfill a variety of functions.

Some of the most popular actuators are servo motors, electromagnets, hydraulic cylinders, and piezoelectric and pneumatic elements.

A single-axis actuator can generate linear motion by exerting a force on an object. This force can for example be generated by using a motor or a liquid. This causes linear motion, which manifests itself in the form of a straight line or circle. Design engineers frequently use single-axis actuators to move certain machines and equipment. The actuator can generate a variety of motions, including continuous or intermittent motion.

What must be considered when mounting single-axis actuators?

A single-axis actuator assembly generally requires a rotary guide unit, a pinion, a lead screw and electronics that control everything. A motor can be additionally required for direct drive control. To mount the actuator, mounting brackets and a frame must also be provided to secure the components. If the actuator is mounted directly to a robotic arm, an adapter specifically designed for this purpose is required. A bearing set should be also available to align and protect the components.

1. Verify that all mechanical and electrical connections are correct.
2. Verify that the actuator size matches the requirements of the system.
3. Make sure that the actuator mounting position provides enough space to operate the actuator.
4. Verify that the actuator is supplied with the correct voltage and frequency.
5. Make sure that the actuator is attached securely and cannot slide out of position.
6. Check that the actuator connections are suited for operation in the system.
7. Regularly check the cable connections of the actuator.

What is a screw drive?

A screw drive is a mechanical element that converts rotary motion into linear motion. It usually consists of a threaded spindle and a nut seated on the spindle. By turning the threaded spindle, the non-rotating nut is linearly displaced on the threaded spindle. Screw drives are available in different versions such as ball screw drives or trapezoidal screw drives.

What is the difference between ball screw drives and trapezoidal screw drives?

Ball screw drives and trapezoidal screw drives differ in terms of their specific properties and applications.

Ball screw drives are usually used for high precision and high speed requirements, while trapezoidal screw drives are used at low speeds with a focus on self-locking action.

Ball screw drives allow for higher precision and greater starting torque than trapezoidal screw drives. They have less friction than trapezoidal screw drives and are easy to install and maintain. Trapezoidal screw drives, on the other hand, permit a higher load-bearing capacity and are usually more cost-effective than ball screw drives. Trapezoidal screw drives are also capable of carrying higher loads and are therefore well suited for higher torque applications.

There are significant differences in the maintenance and repair of ball screw drives and trapezoidal screw drives. One of the most obvious differences is that ball screw drives have a nut equipped with rolling elements. This means that ball screw drives require more effort when they need to be serviced or repaired.

Another difference is that ball screw drives are usually used in applications with high accuracy requirements. This means that ball screw drives must be preloaded and adjusted precisely during maintenance and repair due to the higher accuracy requirement. Frequently, this is less expensive in trapezoidal screw drives due to the inherently lower accuracy requirements. Lastly, ball screw drives and trapezoidal screw drives differ in terms of their maintenance and repair costs. Ball screw drives can be more expensive to manufacture due to their higher precision, while trapezoidal screw drives are usually more cost-effective.

• Ball screw drives can be adjusted much more precisely, without backlash and therefore provide higher precision when changing direction than trapezoidal screw spindles.
• Ball screw drives also have significantly lower friction resistance, which has a positive effect on various aspects. The lower friction achieves a lower breakaway force, resulting in a reduced stick-slip effect.
• Ball screw drives permit a high feed rates of up to 250 m/min.
• Ball screw drives require more installation space than trapezoidal screw drives.
• The manufacturing process for trapezoidal screw drives is less complex, which usually makes it more cost-effective.

Ball screw drives or belt-driven actuators - which choice is best?

Ball screw actuators are an efficient and reliable solution when it comes to actuator control. They offer a number of advantages over belt-driven actuators.

The first and probably most obvious advantage is their higher efficiency. Ball screw drives transfer forces with less friction and losses than belt transmissions, resulting in higher overall efficiency. Another advantage is precision. Ball screw drives are able to generate precise movements with low positioning accuracy. This precision is critical for many applications, especially in applications that require high mechanical accuracy of the gear drives.

Lastly, ball screw drives provide a long service life with reliable performance. The gears are very wear-resistant and have very little play, resulting in a longer service life. Ball screw drives are also less susceptible to vibrations and malfunctions.

The essential difference between ball screw drives and belt-driven actuators is the type of drive action. Ball screw drives use a ball screw to generate linear movements. Belt driven actuators use a belt and pulley system to create rotary motion.

Tips for lubricating ball screw drives

Ball screw drives are a very reliable, precise and durable drive system. However, regular maintenance is required to ensure that the system continues to function correctly and efficiently.

In order to maximize the service life of a ball screw drive, it is advisable to carry out regular maintenance work. Typical maintenance work includes lubricating the balls, inspecting the balls for wear, and checking the tightening torques or lubricant, depending on the application. It is recommended that the system be inspected at least once a year to ensure that the components are in good condition.

Ball screw drives must be lubricated differently depending on the application. As a rule, it is recommended to lubricate ball screw drives after installation and after each maintenance cycle. When ball screw drives are used in a rough or dirty environment, they must be lubricated more frequently to ensure optimum performance.

Certain components should be inspected when maintaining ball screw drives to ensure they are operating correctly.

These include:

• the balls
• the threads
• the bearings
• the recirculating ball rings
• the screws and the shafts

Learn more about this topic in our blog about Lubrication of Ball Screw Drives – Lubricants, Application Areas and General Information.

MISUMI manufactures a wide range of linear motion systems made from high-quality components. The product catalog includes a wide range of drives and linear technologies suited for a wide range of industrial applications.

Products from MISUMI are suited for a variety of applications, from automation to robotics applications. These include linear drives, linear positioning systems, linear guides, linear motors, and other linear components. MISUMI provides a wide range of accessories including linear couplings, linear sensors and linear encoders.

MISUMI’s customers can tap into a wide range of application support, such as technical support, design and engineering support, and fast shipping. With its quality products, professional services and extensive support services, MISUMI is a preferred partner for customers all over the world.

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