Note: Please complete one data sheet for each screw size.
Customer RFQ technical data sheet
NOTE #1: Technical references and definitions are according to ISO 3408-1 to 3/1991
NOTE #2: WPC produces screws with a "gothic (ogival) groove" profile [See ISO 3408-1 1991 E/F]
TERMINOLOGY & DEFINITIONS:(according ISO 3408-1 : 1991)
Positioning ball screw
screw used for precision positioning which enables
the indirect measurement axial travel from the angle
of rotation and the lead, without backlash (preload).
Transport ball screw
- Ball screw the travel of which is measured directly by a separate measuring system independent of the angle of rotation and lead of the ball screw.
Pitch circle diameter
- The diameter of the cylinder containing the centers of the balls screw which are in contact with the screw shaft and the ball nut body at the theoretical contact points.
- The value used for shaft diameter designation (without tolerance).
- Ratio of the ball track radius of the ball screw shaft, ( rs ), or of the ball nut body, ( rn ), to the ball diameter, ( Dw ).
Nominal contact angle
- The angle between a plane perpendicular to the ball screw shaft axis and the resultant of the forces transmitted by a ball track to a rolling element.
Backlash (axial play)
- Total free axial displacement between the ball nut body and the ball screw shaft when there is no rotation between the two components.
- Lead value used for general identification of size (without tolerance).
- Product of the number of starts and nominal lead.
- The number of starts of the thread.
- The portion of the travel to which the specified accuracy is not applicable.
- The product of the nominal lead times the number of revolutions.
- The product of the specified lead times the number of revolutions. In some cases, the specified travel is represented by a nominal travel and a travel compensation value.
- The difference between the specified travel and the nominal travel within the useful travel.
~within useful travel
~within 300 mm travel
~within 2p rad
- The corresponding band width parallel to the actual mean travel.
- Travel variation corresponding with band width of (Vup)
- Travel variation corresponding with band width of (V300p)
- Travel variation corresponding with band width of (V2pp)
Tolerance on specified travel
- Half the difference between the maximum and minimum values of the permissible actual mean travel, 2ep.
- For an individual ball screw, the number of revolutions that the ball screw shaft makes in relation to the ball nut body before the first evidence of fatigue develops in the material of one of them or in the rolling elements.
Basic rating life
- For an individual ball screw, or groove of apparently identical ball screws operating under the same conditions, the life associated with a 90% of achieving the stated life.
Basic dynamic axial load rating
- The static centric axial load that corresponds to a total permanent deformation of ball and track at the most heavily stressed point of contact between the ball and the ball track of 0,0001 times the ball diameter.
Basic static axial load rating
- The constant centric axial load that a ball screw can theoretically endure for a basic rating life of one million revolutions.
Equivalent load rating
- The mean load that will result in the same life as a combination of various loads.
- Force applied on a group of balls and ball tracks, for example by their axial displacement relative to another group, to eliminate backlash and to increase rigidity.
Dynamic drag torque
- Torque required to rotate the preloaded ball nut relative to the ball screw shaft, or vice versa, in the absence of an internal load and any friction torque of the end seals.
Total dynamic drag torque
- Torque required to rotate the preloaded ball nut relative to the ball screw shaft, or vice versa, in the absence of an external load but including the friction torque of the end seals.
- Maximum compressive axial load that can be applied to the ball screw without resulting in permanent structural deformation to it.
Axial rigidity; stiffness; spring rate
- A measure of the resistance of the ball screw to axial deflection (load per unit of deflection).
- The resistance to deflection (is expressed by spring rate).
- The amount of elastic deformation under a certain load.
- Rotational speed of the bal nut or ball screw shaft that produces resonant vibrations of the ball screw.
DN rating value
- The product of the Pitch Circle Diameter and the rotational speed of the ball screw (for WPC ball screws is less equal to 70000).
- Balls smaller than load balls used when intend to reduce the contact friction.
« p »
- Index for permissible values.
« a »
- Index for actual values.
Dimensions & Section of ball screw and nut assembly
do nominal diameter d1 ball screw shaft outer diameter d2 ball screw shaft root diameter d3 journal diameter D1 ball nut body outer diameter D2 ball nut body root diameter D3 ball nut body internal diameter Dpw pitch circle diameter Dw ball diameter l1 thread length Ph lead a nominal contact angle φlead angle
Permissible travel deviation and travel variation in relation to the nominal travel