MOSIONX lead screw There are many different types; generally, the first few letters of the model designation indicate the type of MOSIONX ball screw. The diameter refers to the diameter of the rolling elements in the MOSIONX ball screw and is not explicitly indicated in the model number itself. Instead, it is specified in the technical parameter tables provided by each manufacturer. This diameter is typically related to the nominal diameter and the lead of the screw. Regarding preload, users do not need to know the specific preload force or the exact preload method—simply select the appropriate preload level based on the manufacturer’s sample specifications. Some manufacturers calculate only the total length, while others require the user to provide the thread length. So, what are the key considerations when selecting a MOSIONX ball screw?

　　1. Installation requirements

　　The fixed-fixed installation method is suitable for applications with high precision requirements or those that are sensitive to temperature. Before installation, accurately measure the distance between the two fixed points and precisely calculate the axial elongation under both normal temperature conditions and operating conditions. During installation, apply a preload force to ensure that the screw's axial elongation matches its elastic elongation—ideally, as close as possible to the temperature rise during operation.

　　According to GB standards, MOSIONX ball screws are classified into two categories: P-type and T-type—namely, transmission-type and positioning-type. Their accuracy grades include levels 1, 2, 3, and 4, among others. In foreign products, regardless of whether they are used for transmission or positioning, the tolerance ranges typically fall within C0 to C10 or specific values. Generally speaking, for general-purpose machinery or conventional CNC machines, the tolerance level is below C7; for high-precision CNC machines, it’s above C5 (±0.018) and below C3 (±0.008); and for optical or inspection machinery, the tolerance level is C3 or higher.

　　2. Length

　　This refers to the outer diameter of the lead screw. Common specifications include 12, 14, 16, 20, 25, 32, 40, 50, 63, 80, 100, and 120. However, please note that among these specifications, manufacturers typically stock only sizes from 16 to 50; in other words, most of the other diameters are available only as backorders. The length of the lead screw consists of two parts: the total length of the thread and the effective stroke. The number of balls is usually indicated after the model number—in general, the larger the value, the greater the load capacity and the longer the nut’s length. Additionally, grinding applies only to screws; nuts are always ground.

　　3. Accuracy

　　Due to differences in manufacturing processes, they can achieve varying levels of precision. Currently, the high precision attainable through roll forming is C5. I understand that only REXROTH can achieve this level of precision. This means you cannot move radially or axially, but you can perform circular motion.

　　There are three common types: fixed-fixed installation, fixed-support installation, and non-fixed installation. However, when some users need to reinstall the ball bearings outside the nut due to improper use, they should pay attention to this parameter. Dimensions are typically accurate to within 0.001. Of course, we do not recommend that users attempt to install the ball bearings themselves; otherwise, even if the product is still under warranty, the manufacturer will not provide free maintenance.

　　4. Preloading

　　The fixed support installation method is suitable for most applications, as the axial freedom at the support end allows for axial expansion caused by temperature increases during operation. As a reference value: for a lead screw 1 meter long, a temperature increase of 1 degree will result in an axial expansion of 0.01 mm. The support provides radial restraint but allows axial and circumferential freedom. This means it remains radially stationary while permitting axial movement and circumferential rotation.