The ball screw is a precision mechanical system in which steel balls are inserted between the threaded shaft and the concave-threaded nut, rolling within a helical raceway. These balls serve to convertsliding friction into rolling friction, reducing energy loss and improving efficiency. The helical groove, with a hemispherical cross-section, maintains the same pitch as the screw but with a slightly larger average diameter, allowing for smooth and stable movement.
This is the most widely used mechanism for converting rotational motion into linear motion; it is considered an evolution of the traditional screw-and-nut mechanism and offers greater precision, a long service life, and high efficiency (approximately 90%).
THK designs and manufactures a complete range of ball screws, available both with “Caged Ball” technology —which reduces friction and noise—and with traditional full-complement technology.
In addition to these, the product line also includes BNS precision splined shafts, which combine rotational and linear motion in a single component, offering a compact and highly efficient solution for numerous industrial applications.
Ball screw
Ball screws compliant with ISO 3408 (DIN 69051)
Ball screws, manufactured in accordance with DIN standards, ensure high precision and efficiency in motion transmission. During operation, the balls under load slide between the screw shaft and the nut, absorbing the axial load; they are then deflected through a groove with an integrated deflector in the nut, before re-entering the adjacent raceway and returning to the loaded area. This closed circuit allows the balls to perform a continuous rotary motion, reducing friction and wear.
Available preload methods:
They are available in precision class P5, ideal for applications requiring high accuracy and repeatability.
Caged ball screw
High-load ball screw – HBN model with caged ball technology
The HBN ball screw, designed for high loads, features an optimized internal design that increases therated load capacity compared to conventional ball screws.
Key features:
Caged ball screw
Ball screws featuring caged ball technology and a reinforced recirculation channel are designed to ensure high feed rates.
The SBK version features a square pitch (where the pitch is equal to the ball's diameter) and allows speeds exceeding 2 m/s.
The SBN high-speed ball screw is equipped with caged ball technology, which eliminates collisions and friction between the balls and extends the lubrication life. This results in low noise, excellent torque characteristics, and long periods of maintenance-free operation.
Thanks to the reinforcement of the recirculation tube and the optimization of the tangential entry and exit of the balls, it was possible to achieve a DN value of 130,000. Furthermore, the preload achieved by offsetting the pitch at the center of the volute allows for a shorter and more compact volute compared to the double volute, where the preload is instead generated by a central spacer.
In the high-speed SBK model, the balls are kept at equal distances by a cage that eliminates collisions and friction, ensuring high lubricant retention. This results in low noise, reduced vibration at high speeds, and long-term maintenance-free operation. Furthermore, the optimized recirculation structure, with exit from the thread and entry into the channel in a tangential direction, allows for a DN value of 210,000.
Ball screw
The BLR model is a recirculating ball screw unit in which the recirculating nut is integrated with a support bearing. This is an angular contact bearing with a 60° contact angle, which accommodates a large number of balls and ensures high axial rigidity. The BLR model is available in two versions: precision ball screw and rolled ball screw.
The DIR ball screw, on the other hand, is the standard version, featuring a design that combines a simple ball screw with a support bearing. In this model, the nut acts as a recirculation mechanism via deflectors: the balls travel along the groove of the deflector mounted in the nut, pass into the adjacent raceway, and return to the load area, thus completing a continuous rolling cycle.
In the DIR version, preload is achieved through a pitch offset, which provides additional threads on both the right-hand and left-hand sides at the center of the nut. This sets the axial play below zero (preload), allowing for smoother, more compact movement compared to the traditional double-nut type (which requires a central spacer).
The support bearing incorporates two rows of DB-type angular contact bearings with a 45° contact angle, ensuring proper preload. In addition, the pulley mounting collar is integrated directly into the ball screw nut.
Ball screw
This screw design, unique in the world, combines the action of a ball screw with that of a spline screw. Thanks to two nuts mounted on the screw, a rotary motion is produced when the nuts move without relative rotation; in the presence of relative rotation, however, rotary-translational motions are generated.
Because the recirculating ball nut is integrated with a support bearing, the unit is extremely precise and compact. Furthermore, the low inertia of the lightweight nut ensures high dynamic responsiveness.
The support bearing on the ball screw has a contact angle of 60° in the axial direction, while the one on the ball groove has a contact angle of 30° in the direction of the load, thus ensuring very rigid shaft support. A dedicated rubber seal, supplied as standard, prevents the entry of foreign particles. The recirculating ball screw is also easy to install: simply secure it to the housing using bolts (recommended housing inner diameter tolerance: H7).
This system allows for three different movement modes using a single shaft:
Thanks to these features, the system is particularly well-suited for machines that require a combination of rotary and linear movements, such asthe Z-axis of SCARA robots, assembly robots, automatic loaders, and ATC systems for machining centers.
Ball screw
This screw model is designed for use in compact, high-speed machines, ensuring stable and reliable performance even under prolonged operating conditions.
The balls are guided in a tangential direction, allowing them to reach a maximum rotational speed of 5,000 rpm and a DN valueof up to 160,000.
The torque remains stable even during long periods of high-speed operation, ensuring consistency and precision.
The newly designed circulation components enable an optimized recirculation system, improving system efficiency and reducing vibration and wear.
The nut dimensions comply with DIN 69051-5 standards, ensuring compatibility and easy integration into existing projects.
Ball screw
Ball screws compliant with ISO 3408 (DIN 69051)
Ball screws, manufactured in accordance with DIN standards, ensure high precision and efficiency in motion transmission. During operation, the balls under load slide between the screw shaft and the nut, absorbing the axial load; they are then deflected through a groove with an integrated deflector in the nut, before re-entering the adjacent raceway and returning to the loaded area. This closed circuit allows the balls to perform a continuous rotary motion, reducing friction and wear.
Available preload methods:
They are available in precision class P5, ideal for applications requiring high accuracy and repeatability.
Caged ball screw
High-load ball screw – HBN model with caged ball technology
The HBN ball screw, designed for high loads, features an optimized internal design that increases therated load capacity compared to conventional ball screws.
Key features:
Caged ball screw
Ball screws featuring caged ball technology and a reinforced recirculation channel are designed to ensure high feed rates.
The SBK version features a square pitch (where the pitch is equal to the ball's diameter) and allows speeds exceeding 2 m/s.
The SBN high-speed ball screw is equipped with caged ball technology, which eliminates collisions and friction between the balls and extends the lubrication life. This results in low noise, excellent torque characteristics, and long periods of maintenance-free operation.
Thanks to the reinforcement of the recirculation tube and the optimization of the tangential entry and exit of the balls, it was possible to achieve a DN value of 130,000. Furthermore, the preload achieved by offsetting the pitch at the center of the volute allows for a shorter and more compact volute compared to the double volute, where the preload is instead generated by a central spacer.
In the high-speed SBK model, the balls are kept at equal distances by a cage that eliminates collisions and friction, ensuring high lubricant retention. This results in low noise, reduced vibration at high speeds, and long-term maintenance-free operation. Furthermore, the optimized recirculation structure, with exit from the thread and entry into the channel in a tangential direction, allows for a DN value of 210,000.
Ball screw
The BLR model is a recirculating ball screw unit in which the recirculating nut is integrated with a support bearing. This is an angular contact bearing with a 60° contact angle, which accommodates a large number of balls and ensures high axial rigidity. The BLR model is available in two versions: precision ball screw and rolled ball screw.
The DIR ball screw, on the other hand, is the standard version, featuring a design that combines a simple ball screw with a support bearing. In this model, the nut acts as a recirculation mechanism via deflectors: the balls travel along the groove of the deflector mounted in the nut, pass into the adjacent raceway, and return to the load area, thus completing a continuous rolling cycle.
In the DIR version, preload is achieved through a pitch offset, which provides additional threads on both the right-hand and left-hand sides at the center of the nut. This sets the axial play below zero (preload), allowing for smoother, more compact movement compared to the traditional double-nut type (which requires a central spacer).
The support bearing incorporates two rows of DB-type angular contact bearings with a 45° contact angle, ensuring proper preload. In addition, the pulley mounting collar is integrated directly into the ball screw nut.
Ball screw
This screw design, unique in the world, combines the action of a ball screw with that of a spline screw. Thanks to two nuts mounted on the screw, a rotary motion is produced when the nuts move without relative rotation; in the presence of relative rotation, however, rotary-translational motions are generated.
Because the recirculating ball nut is integrated with a support bearing, the unit is extremely precise and compact. Furthermore, the low inertia of the lightweight nut ensures high dynamic responsiveness.
The support bearing on the ball screw has a contact angle of 60° in the axial direction, while the one on the ball groove has a contact angle of 30° in the direction of the load, thus ensuring very rigid shaft support. A dedicated rubber seal, supplied as standard, prevents the entry of foreign particles. The recirculating ball screw is also easy to install: simply secure it to the housing using bolts (recommended housing inner diameter tolerance: H7).
This system allows for three different movement modes using a single shaft:
Thanks to these features, the system is particularly well-suited for machines that require a combination of rotary and linear movements, such asthe Z-axis of SCARA robots, assembly robots, automatic loaders, and ATC systems for machining centers.
Ball screw
This screw model is designed for use in compact, high-speed machines, ensuring stable and reliable performance even under prolonged operating conditions.
The balls are guided in a tangential direction, allowing them to reach a maximum rotational speed of 5,000 rpm and a DN valueof up to 160,000.
The torque remains stable even during long periods of high-speed operation, ensuring consistency and precision.
The newly designed circulation components enable an optimized recirculation system, improving system efficiency and reducing vibration and wear.
The nut dimensions comply with DIN 69051-5 standards, ensuring compatibility and easy integration into existing projects.
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