Types of THK ball screws
THK ball screws are classified according to the shape of the ball track as shown below
- Circular-arc ball screw: A ball screw in which the ball track is an arc of a circle. The circular-arc ball screws are divided into 2 types, the circular-arc groove type and the circular-arc gothic arch type.
- Non-preloaded ball screw: A ball screw that does not have a preload (internal stress to remove clearance) is placed on the balls. It is a ball screw in which the axial play exists to enable smooth movement. Because the axial play is present, it is possible to move the ball screw smoothly with minimal friction. Therefore, non-preloaded ball screws are suitable for applications that require high speeds, high accelerations, or low rigidity.
- Preloaded ball screw: This type of ball screw is the opposite of the non-preloaded ball screw. It has an internal load that eliminates clearance. This internal preload enhances the rigidity of the ball screw. Preloaded ball screws are a better option when high positioning accuracy or high rigidity is required.
- Ground ball screw: THK ground ball screws are produced using a grinding process, which provides precise dimensions and tight tolerances. This manufacturing method ensures excellent performance, high accuracy, and repeatability. Ground ball screws are commonly used in applications that demand high precision and control.
- Rolled ball screw: Rolled ball screws are manufactured by cold rolling metal strips into the shape of a screw. This method ensures cost-effective production while maintaining high-quality standards. Rolled ball screws offer smooth operation, high efficiency, and durability. They are suitable for a wide range of industrial applications.
- Miniature ball screw: Miniature ball screws are designed with a smaller diameter and pitch than standard ball screws. They are commonly used in compact and precise applications. Miniature ball screws provide high accuracy, resolution, and repeatability in a small form factor. They are ideal for robotics, medical devices, semiconductor equipment, and other precision machinery.
- Large-size ball screw: Large-size ball screws are designed to handle heavy loads and provide high thrust capacity. They have a larger diameter and pitch than standard ball screws, making them suitable for heavy-duty industrial applications. Large-size ball screws offer high rigidity, precision, and reliability in demanding environments.
- High-lead ball screw: High-lead ball screws have a larger lead or pitch than standard ball screws. They are designed to achieve higher speed and efficiency in linear motion systems. High-lead ball screws offer rapid positioning and fast travel rates while maintaining accuracy and repeatability. They are commonly used in applications that require high-speed performance.
- Support unit: The ball screw support unit is an assembly that supports and positions the ball screw. It includes bearing blocks, support bearings, housings, and other components. The support unit ensures the proper alignment and smooth operation of the ball screw. It also provides rigidity and stability to the entire system. The ball screw support unit is essential for maintaining precision and performance in various applications.
Specifications and maintenance of THK ball screws
THK manufactures a variety of ball screws to meet the diverse needs of different industries. Here are the specifications of some popular types of THK ball screws.
- Model SBN: The diameter of the shaft is from 8 to 50 mm, and the lead is from 2 to 25 mm.
- Model SBK: The diameter of the shaft is from 10 to 50 mm, and the lead is from 10 to 50 mm.
- Model SRE: The diameter of the shaft is from 8 to 25 mm, and the lead is from 2 to 20 mm.
- Model BLK: The diameter of the shaft is from 10 to 50 mm, and the lead is from 10 to 50 mm.
- Model EPF: The diameter of the shaft is from 15 to 50 mm, and the lead is from 10 to 50 mm.
THK ball screws can provide excellent performance and extend service life if they are properly maintained. Here are some points for maintaining THK ball screws.
- Clean the surface: Regularly clean the surface of the ball screws with a soft brush or dry cloth to remove dirt and debris. This can prevent contaminants from entering the ball screw thread raceway and affecting the performance of the ball screw.
- Lubrication: Proper lubrication is essential to the smooth operation of ball screws. Apply the specified lubricant to the surface of the ball screw to ensure that the balls and threads are well lubricated. Regularly check the lubrication situation of the ball screws to ensure that there is no lubricant shortage or excess.
- Check for damage: Regularly inspect the surface of the ball screws for damage, such as corrosion, scratches, or dents. If any damage is found, deal with it immediately to avoid further deterioration.
- Check backlash: Backlash refers to the clearance between the ball and the screw thread. Excessive backlash can affect the positioning accuracy of the ball screws. Regularly check the backlash of the ball screws and adjust them if necessary to maintain proper performance.
- Avoid overload: Do not overload the ball screw to prevent premature wear or damage. Follow the manufacturer's recommendations on load capacity and usage limits.
Scenarios
The application of THK ball screws in the machinery industry is versatile. Here are some usage scenarios of THK ball screws in various industries.
THK ball screws are frequently used in automotive assembly lines to assist in tasks such as body welding, chassis assembly, and engine installation. THK ball screws can also be used in robotics, which are used for welding, painting, and assembly tasks in the automotive industry. They can also be used in automated inspection equipment to perform precise measurement and quality control tasks.
In the machine tool industry, THK ball screws are commonly applied to CNC machine tools. The ball screws convert the rotary motion of the motor into precise linear motion for tool positioning and feed control. This ensures the high accuracy and repeatability of the machining process.
In the medical industry, THK ball screws play an essential role in various medical equipment, such as diagnostic equipment, imaging devices, and surgical robotics. They are used to achieve precise positioning and movement in equipment, thereby supporting accurate diagnosis and treatment.
In the 3D printing industry, THK ball screws are often used in high-precision 3D printers. They convert the rotary motion of the motor into controlled linear movement of the print head or build platform. This enables the 3D printer to achieve intricate details and high-resolution printing.
In the aerospace industry, THK ball screws are commonly used in aircraft manufacturing, satellite assembly, and space exploration equipment. They are used in tasks such as deploying solar panels, antenna positioning, and controlling robotic arms in space missions. The ball screws provide reliable and precise mechanical movement in the harsh environment of outer space.
Choosing the right THK ball screw
When selecting THK ball screws for various industrial applications, several factors should be taken into consideration to ensure optimal performance and compatibility.
- First, it's important to determine the required load capacity of the machinery or equipment. This includes considering the maximum load requirements as well as any additional loads, such as acceleration forces or tool weights. Selecting a ball screw with a load capacity higher than the application's maximum load will help ensure stability and performance.
- Next, the desired speed and positioning accuracy of the application should be considered. This entails looking at the required travel speed and resolution to determine the appropriate lead (pitch) and screw diameter for the application. A ball screw with the right combination of lead and diameter should be chosen to achieve the desired speed and accuracy.
- Another important consideration is the required rigidity of the system. This is especially critical for applications that experience high thrust forces or that require minimal deflection. Selecting a ball screw with the right diameter and support configuration is crucial for meeting the rigidity demands of the application.
- Additionally, it's important to evaluate the environmental conditions of the application, such as temperature, moisture, and the presence of contaminants. Choosing a ball screw with appropriate sealing and coating options will help ensure it can withstand the environmental challenges it may face.
- Finally, it's essential to consider the compatibility of the ball screw with other system components, such as the motor and controller. Ensuring that these components are properly matched and can work together seamlessly is vital for achieving optimal performance.
THK ball screws Q&A
Q1. What are the advantages of THK ball screws?
A1. THK ball screws provide many benefits for customers. Efficiency is one advantage. The THK ball-bearing system allows for high efficiency at 90-95% and positional accuracy, which is crucial for high-precision applications. Also, THK ball screws have a low friction coefficient, which reduces the torque required for operation and increases energy efficiency. Moreover, the ball-bearing design of the THK screw creates smooth motion, which can be ideal for high-speed and high-volume manufacturing applications that require quick cycle times.
Q2. What are the key design features of THK ball screws?
A2. The key design features of THK ball screws include the cylindrical outer and ball-bearing design, which provides smooth and efficient linear motion. Another key design feature is the recirculation system that uses ball bearings to recirculate the load. This system contributes to the high load capacity and rigidity of the screws. The precision-ground helical grooves ensure precise positioning and repeatability. Moreover, the ball screws are available in different ball configurations, such as single, double, or super, to meet various application requirements. Additionally, the screws come in different material options, such as stainless steel, carbon steel, or alloy steel, to suit specific environmental and performance needs.
Q3. What industries use THK ball screws?
A3. Many industries use THK ball screws for various applications. Some common industries include manufacturing and automation, aerospace, automotive, medical, robotics, semiconductor production, and food and beverage. In the manufacturing and automation industry, THK ball screws can be used in CNC machines, 3D printers, packaging machines, and material handling equipment. In the automotive industry, they are used in automotive assembly, welding, and painting robots. In the aerospace industry, they are used in aircraft and space vehicle control mechanisms. In the medical industry, they are often used in medical imaging devices and surgical robots.
