PMI turned-grade ball screw

PMI turned-grade ball screw

Introduction to Turned-Grade Ball Screws

The manufacturing process and equipment used by PMI for producing rolled-ball screws at the turning stage differ from those employed by other manufacturers. Our company utilizes advanced turning technology combined with a numerically controlled thread-rolling machine imported from Bad Duben, Germany. We maintain stringent quality controls throughout the entire process—from the selection of screw material and turning operations to intermediate-frequency surface heat treatment and post-processing—ensuring that our products meet the highest quality standards required by our customers.

The combination of a precision-ground ball screw and a ground-class nut replaces the conventional transmission methods using Acme lead screws and trapezoidal lead screws, offering advantages such as smoother operation, reduced friction, and minimized axial backlash. Additionally, this solution features rapid delivery and low cost.

PMI Turned-Grade Ball Screw Features

The nuts used for turning have high precision.

The manufacturing process for turned-grade nuts is identical to that of ground-grade nuts. After surface hardening treatment, they are precisely ground using an internal thread grinding machine to ensure durability and smooth operation.

High nut interchangeability

When the screw and nut are without preload, within the allowable maximum axial backlash, screws of the same specification can be fitted with nuts of different designs.

Lead accuracy of turned and ground ball screw (e₃₀₀)

According to ISO 3408-3, the definition of lead accuracy for PMI turned and ground ball screws is: Within the effective thread length, the allowable cumulative lead error over any 300 mm segment, as specified in Table 1.

Table 1: Comparison of Lead Accuracy

e ₃₀₀ (Allowable cumulative lead error over any 300 mm within the effective thread length range)