Articles on: Learning & FAQ

Parameters of Linear Motor Screw Rod

Nominal diameter of screw rod

It is the shaft diameter of the screw. Generally, the larger the shaft diameter, the greater the load.

The load that screws with different shaft diameters can bear can be viewed in the manufacturer's catalog. The relevant parameters are dynamic rated load and static rated load.

The static rated load refers to the rated load that the screw can bear in a static state. However, the screw cannot always be stationary during use, so we only need to pay attention to the dynamic rated load. The smaller the actual load, the longer the theoretical life of the screw.

Lead of screw rod

Lead refers to the distance the nut moves linearly when the screw rotates once. Common leads are (unit: mm): 1, 2, 4, 5, 6, 8, 10, 16, 20, 25, 32, 40. The parameters related to the lead are the nut movement speed and the ball screw. The straight line thrust available.
The larger the lead, the faster the linear motion speed at the same rotation speed. The specific calculation relationship is:

v: moving speed of the nut (unit: mm/s)
r: Rotation speed of screw (unit: r/s)
i: Lead (unit: mm)
The relationship between lead and screw thrust:
F =(2*π*T*n)/i
F: Screw thrust (unit: N)
T: Torque provided by the motor (unit: N·m)
n: Transmission efficiency (the transmission efficiency of ball screw is generally 85%-95%)
i: lead (unit: m)

The pitch of the screw rod

The pitch and lead of the screw are related to each other. The larger the pitch, the larger the lead. This is because the pitch is part of the lead,
The lead is a multiple of the pitch. Therefore, the pitch and lead of the screw are closely related. But among the linear motors we sell so far, the multiple relationship between the two is 1, so the pitch parameter can be ignored. Daily discussions also mainly focus on the two parameters of screw diameter and lead.


If the customer has a linear motor from another manufacturer, he or she would like a matching nut. The two screws come from different manufacturers. Even if the pitch and lead are the same, their nuts cannot be mixed and must be matched according to the actual threads.

Updated on: 15/09/2023

Was this article helpful?

Share your feedback


Thank you!