What is the DmN value of a ball screw?
The DmN value of a ball screw is the limit value that serves as a guideline for determining whether the component that scoops up the steel balls can withstand the conditions of use in terms of strength.
The tip of the circulating part that scoops up the steel balls is shaped like a bird's beak or an animal's tongue (sometimes called a tongue) in order to scoop up the steel balls. (See the diagram below.)
When the ball screw operates, steel balls with kinetic energy collide with and pass through the inner wall of this part, so this part is subjected to repeated loads. The faster the revolution speed of the steel balls, the greater the impact force. If the balls are operated beyond their strength limit, they will not be able to withstand the repeated stress and the tongue will break, causing the ball screw to lose its function.
The revolution speed is expressed as the so-called DmN value, which is the product of the steel ball's orbital center diameter: Dm (mm) and the rotation speed: N (min-1). In order to prevent damage to the tip, it is necessary to set operating conditions that do not exceed the DmN value shown in the table below.
The DmN values of KURODA's product groups are set to the values shown in the table below by series.
- Note: If the above DmN value or rotation speed: N exceeds 5000 min-1, please contact KURODA.
Technical information list about Ball Screws
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