Precision (Lead Error, Friction Torque, Critical Tolerances)

Under the headline "precision" DIN / ISO standards are explained as they apply to ball screws, how accuracies are defined, and the acceptance or specification criteria derived from these standards.

• Lead Accuracy
• Friction Torque
• Critical Tolerances
• Run-out Tolerances

Furthermore here you will find our recommendation for Mounting Tolerances. 

The DIN standard differentiates between positioning ball screws and transport ball screws.

Positioning ball screws are normally used in high-precision applications (like machine tool) and are usually equipped with a ground ball thread.

Transport ball screws are predominantly used for travelling and moving applications. Typical applications are axes for handling systems. Ball thread of such screws is usually rolled or whirled. Per DIN standard the tolerance classes for Positioning ball screws are described as "P" while transport ball screws classes are described as "T".

Steinmeyer uses this designation as per DIN:

P0 - P5 for Positioning ball screws
T5 - T10 for Transport ball screws

In general, all acceptance criteria should be reviewed and agreed upon between Steinmeyer and our customer.  This is especially relevant for those applications where special demands are required, for example a lead accuracy of class 5 but friction torque variation consistent with accuracy class 1.  In this example, Steinmeyer produces a ball screw with economical class 5 lead accuracy but with much lower friction torque variation.

If such custom specifications are not established, standard values of the respective accuracy class apply.