The Difference between Rolled and Ground Ball Screw

Customers often ask the difference between rolled and ground ball screw, the production process and accuracy are different, but the overall function is the same. An ideal product that converts rotary motion into linear motion or converts linear motion into rotary motion.

1, The difference of production process

Ball screw from the production process is divided into rolled ball screw and ground ball screw two categories.

rolled ball screw manufacturing process

Rolled ball screw processing technology is relatively simple, first in the high-quality screw shaft material to cut a certain depth of the slot, and then rolled by thread rolling machine, so there will be an extruded groove above the screw thread. The production process is high degree of automation, very suitable for mass production, and can be made into different lengths of ball screws according to requirements, and from a technical point of view, the product consistency is higher than the ground ball screw.

ground ball screw manufacturing process

Ground ball screw is based on the rolling process with a special cylindrical grinding machine for the arc groove shape and other dimensions precision machining, grinding each thread through the grinding machine, so there is no thread groove.

Through repeated grinding to achieve accuracy requirements, after the production, use the precision instrument to measure the overall accuracy, only choose the finished product achieve the accuracy requirements, the unqualified part will be cut off. So the ground product inventory has no fixed length. And rolled ball screw, with lower accuracy requirements, the finished product can maintain consistency, which is why the length can be customized.

2, The difference of accuracy level

The accuracy level refers to the error value of ball screw within any 300mm. For example, the error of rolled ball screw is 50 microns, while the ground ball screw, according to different grades, respectively, 18 or 8 microns.

Rolled ball screw accuracy level is below average, suitable for ordinary equipment with lower precision requirements, cheap and economical. Ground ball screw accuracy level is above average, suitable for CNC machines and other higher precision requirements equipment.

3, The difference of preload level

Preload refers to a method of handling the rigidity of the steel balls to achieve the accuracy of ball screw. The preload standard of the rolled ball screw is P0, the preload of the ground ball screw, according to the different grinding level, respectively, P1 and P2 two kinds.

4, The difference of application scope

Rolled ball screw running smoothly, normal service life, generally used for non-precision positioning, the general reliability occasions. Ground ball screw running smooth, long service life, generally used for precision positioning, high reliability, heavy load occasions.

rolled (left) and ground (right) ball screws
Profiles of rolled (left) and ground (right) ball screws

Rolled ball screw is manufacturing by rolling machine, the accuracy is very low, good manufacturers can barely achieve C5 level, but one advantage is that the production cycle is short and the delivery time is very fast. Ground ball screw manufacturing process is more complex, ground by ultra-precision grinding machine, the accuracy can reach the highest level C0, but the delivery time is very slow! Generally, the same specifications of ground ball screw cost is higher than the rolled ball screw, provided that the mass production. If the output is very small, the cost of rolling will be much higher than grinding. Rolling production is suitable for large-scale production of economic products, high production efficiency. And restricted by production equipment, the less-use large-size products on the market only grinding products for sale.

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