What are Linear Slides and Ball Screws? Development of Linear Motion Elements

For a complete linear transmission component, four necessary transmission components must be supplied, namely linear slides, ball screws, ball splines, and single-axis robots. The main function of the slide rail is to move the object to be moved and lock the object on the sliding seat, the workpiece can run freely on the slide rail through the sliding seat. At the same time, a servo motor is required to be combined with a ball screw to convert the circumference into a linear motion, drag the slider to make a linear displacement, and combine the servo motor and the ball screw to form power.

What are Linear Slides and Ball Screws?

The linear slide rail is a kind of rolling guide, using steel balls and rollers to make a rolling cycle between the slider and the slide rail so that the load platform of the equipment can easily move linearly with high precision along the slide rail. Devices are widely used in machineries, such as medical equipment, semiconductor equipment, automated equipment, and machine tools. It is an indispensable component in various industries. Linear slide rails are composed of guide rails, sliding seats, and rolling elements. A low-friction sliding component for linear motion guidance.

The ball screw is also called the screw and the lead screw. The structure of the ball screw is divided into an inner circulation structure and an outer circulation structure. The ball screw is a transmission mechanical component that puts the steel ball between the nut and the screw, replaces the sliding contact of the traditional screw with rolling contact, and then converts the rotary motion of the steel ball in the nut into a linear motion. General Motors are for rotary motion, but if linear positioning motion is to be done, a screw must be used instead. The ball screw is composed of a screw, nut, steel ball, fixed seat, wiper, and return pipe. The different circulation systems, it is further divided into external circulation type, internal circulation type, end plug circulation type, and end cap circulation type.

Advantages of Linear Slides and Ball Screws:

• The linear slide rail has high transmission efficiency.
• The material of the linear slide rail has a long service life and is suitable for heat treatment.
• Due to the extremely small friction resistance, the linear slide rail can maintain accuracy for a long time: especially its easy lubrication, simple structure, and good effect, so the wear of the contact surface during friction is low, which is conducive to maintaining the walking accuracy for a long time.
• Suitable for high-speed application: it has the advantages of small frictional resistance, low demand for the driving horsepower of equipment, and can save energy.
• Simple assembly and interchangeability: the linear slide rail can be installed on the milled or ground mounting surface, and the processing precision of the linear slide rail can be achieved with fixed assembly steps, which can reduce time and cost. With the feature of interchangeability, the slide block can be arbitrarily assembled on the slide rail of the same type, and maintenance is easy.
• Ball screw has high efficiency, reversibility, zero backlash, high rigidity, high lead accuracy, and many other advantages, making the ball screw one of the important components in the precision technology industry and precision machinery industry recently.

Speed of Linear Slide:

Under normal circumstances, compared with sliding guidance, the difference between the static friction coefficient and the dynamic friction coefficient is small, and the dynamic friction coefficient caused by the feed rate does not change significantly. This is one of the reasons why linear guides are widely used as rolling guides in the machine tool industry where the speed is increasing significantly. Almost all machine tools using linear slide rails are used in conjunction with ball screws. If the ball revolution speeds of linear slide rails and ball slide rails are compared, it can be known that the ball screw travels a longer distance when running the same linear movement. When the linear slide rail is used in pairs with the ball screw, if the speed of the linear slide rail is within the limit speed of the ball screw, there is no problem with the speed of the linear slide rail.

The maximum speed of a single linear slide can reach 100m/min. However, when it is necessary to use a track that exceeds the maximum production length. The track needs to be spliced; it is necessary to pay special attention to controlling the installation error of the spliced part. When the feed speed exceeds 100m/min, it is necessary to select a high-speed special lubricant grade and proper maintenance management. At the same time, it is necessary to pay attention to the installation error of the linear slide rail during assembly. Regarding the influence of mounting error, when there is a parallelism error, the load on the linear slide rail fluctuates because the slide block is limited by the mounting platform. When subjected to high speed and impact force, the life will be significantly reduced. Compared with the ball screw, the running speed of the steel ball of the linear slide rail is slower, and the heat generated is conducted from the installation part to the whole device, and the conduction area is large, so the temperature rise is small. Because the installation machine of the linear slide rail is made of aluminum plate, different types of metal have different thermal expansion coefficients. Even if there is no temperature difference between the two, attention should be paid to the overall deformation caused by temperature changes and the excessive internal stress of the linear slide rail.

A Vision for Future Linear Motion Components:

Linear transmission components are not only used in automated manufacturing, but also include drawer rails for our daily office furniture, photocopying and scanning equipment, and hospital beds for medical use. In the future, in addition to continuing to deepen the automation market, it will also focus on the direction of refinement, miniaturization, and household nation. With the vigorous development of digital equipment, the introduction of medical automation, and the trend of refined household products, TBI’s global transmission period will have the following prospects in the future extended development:

• Medical industry: In the past, slide rail products were used in medical equipment, and most of them were screws used in hospital beds, scanning instruments, vision testing instruments, and other products. However, in the future, automatic scanning equipment, rapid medical testing equipment, and blood screening equipment will all be moving toward higher precision and automation. There will be more and wider demand for high-precision and miniaturized transmission components in the market.
• Entertainment industry: With the rapid development of VR, AR, and MR technologies, the demand for somatosensory equipment has increased. Whether it is a large somatosensory device or a small wearable device, there are different requirements for linear transmission components, which is also the future of A center of gravity worth developing.
• Refined home furnishing and smart home industry: In the past, OA products often used lower-level slide rail drawers due to cost considerations. Note that high-level slide rail components are gradually being introduced into such products.

In addition, it is expected that more and more smart home products will introduce automation functions, which are expected to simultaneously drive the demand for linear transmission components.