Linear motors , also known as linear actuators, are a common type of mechanical equipment used by manufacturing companies in various fields. Installed on production equipment, they provide high-speed, automatic linear motion for the production line, effectively increasing production capacity. As a high-end product, linear motors offer numerous advantages:
The following is a comparison of the main characteristics of lead screws and linear motors:
1. Speed
In terms of speed, linear motors have a significant advantage. A linear motor can reach a speed of 300 m/min with an acceleration of 10g. A ball screw, on the other hand, can only reach 120 m/min with an acceleration of 1.5g. Comparing speed and acceleration, linear motors have a considerable advantage, and their speed can be further increased once the heat generation issue is resolved. In contrast, the combination of a rotary servo motor and a ball screw is significantly limited in terms of speed and difficult to improve further. From a dynamic response perspective, linear motors have an absolute advantage due to their reduced inertia, backlash, and the complexity of their mechanism.
In terms of speed control, linear motors have a faster response and a wider speed range, up to 1:10000. They can reach the maximum speed instantly at startup and stop quickly when running at high speed.
2. Accuracy
In terms of accuracy, linear motors reduce the problem of interpolation lag due to their simple transmission mechanism. Their positioning accuracy, reproducibility accuracy, and absolute accuracy are all higher than those of "rotary servo motor + ball screw" through position detection feedback control, and are easier to achieve.
Linear motors can achieve a positioning accuracy of 0.1μm. The accuracy of a "rotary servo motor + ball screw" configuration is at most 2~5μm.
3. Energy consumption
The "rotary servo motor + ball screw" is an energy-saving and power-enhancing transmission component. When providing the same torque, a linear motor consumes more than twice the energy of a "rotary servo motor + ball screw". Furthermore, the reliability of a linear motor is affected by the stability of the control system and has a significant impact on the surrounding environment. Therefore, effective magnetic shielding and protective measures must be taken to isolate the magnetic field from the rolling guide and to prevent the adsorption of milling chips and magnetic dust.
4. Noise
Linear motors are quiet because they are not constrained by centrifugal force, and there is no mechanical contact during movement, resulting in no friction and noise. Transmission components experience no wear, significantly reducing mechanical losses and avoiding noise caused by cables, steel wires, gears, and pulleys, thus improving overall efficiency.
After prolonged use, the ball screw may experience peeling on the ball surface or problems with the ball screw shaft on the cutting force surface, which indirectly affects the running track of the ball. This causes friction between the nut and the shaft, resulting in vibration and excessive noise.
5. Itinerary
Linear motors can theoretically achieve unlimited travel.
After the ball screw nut has reached its effective stroke, it can still rotate appropriately. However, under normal circumstances, it should not be rotated excessively, otherwise it will damage the ball screw and cause a large number of balls and nuts to fall off. Therefore, it is generally not recommended to advance it too far during operation.
