Stepper motor linear actuator is a device which is used to produce linear motions with the help of stepper driver. Stepper driver is motor which produces rotational motion. Linear actuators use these rotations to achieve linear motion. Linear actuators have a wide range of usage in various types of machinery, ranging from computer disk drives, printers to valves, dampers, etc. and many other features where linear straight is required.
Variety of Stepper Motor Linear Actuator
There are mainly five types of linear actuator present in the market. They are as follows-
Mechanical Actuator: These types of actuators mainly work through mechanical elements such as screw, wheel and axis and cam. Each of them has specific operations –
- Screw: Screw shaft moves in a straight fixed line through turning actuators’ nut. Example of many screws used for actuator operations a lead screw, screw jack, ball screw and roller screw.
- Wheel and axle: Axle may be a cable, stand, belt etc. A wheel is made to rotate which moves the axle in forward or backward, as required, directions. The usual combinations used are hoist, winch, rack and pinion, chain drive, belt drive, rigid chain, etc.
- Cam: Cam used in mechanical actuators is more like a wedge used in normal thrust operations, though it provides a restricted travel than usual wedges. Cam’s peculiar figure offers the requisite thrust at the base of the shaft while rotating.
Mechanical actuators are of three types; those who only provide motion in a backward direction like hoists, chain drive, belt drives; those who only offer forward motion like cam actuators; and those who give straight line motion in both forward and backward direction like lead screws, hydraulic cylinders, etc.
Mechanical actuators pull out its linear motion from the rotating action of the control handle. This conversion is achieved through using screws and gears joined to the control handle. To become accurate in positioning, index markings are employed on the control handle in manual processes.
- Hydraulic Actuators: Hydraulic actuators work on the principle of Pascal’s law which is that in incompressible objects such as some fluids as liquids are can generate a desired amount of force when there is an uneven distribution of pressure. In hydraulic actuators naturally, a hollow cylinder is used which a piston has put in within it. The force created is applied to the contact surface of the piston and the liquid which makes it move along the axis of the piston. Because the liquids used in this process are nearly incompressible so the displacement of the shaft or rather a piston can be well controlled. Example of such actuators is hydraulic car jacks.
- Pneumatic Actuators: Operation of pneumatic actuators is almost similar to hydraulic actuators except for the fluid used in it. The fluid used in the pneumatic actuator is gas. Air compression is the key to its working. Air is pumped into the chamber and pressed out from the other side. The main reason behind the popularity of pneumatic actuators is its simplicity, e., with a simple air compressor, a pneumatic actuator can be powered. However, it is not used generally for some reasons like:
- It can be used for heavy weight lifting, e., scenarios, where a huge quantity of weights is needed to be displaced pneumatic actuators, are no good.
- Most air compressors available in the market are gigantic and noisy. Due to their heavy size, they are difficult to be transported, and even if they are, the cost of transportation is higher.
- Their design makes them vulnerable to leakages.
- Piezoelectric Actuators: Piezoelectric materials are those who increase in size in the account of an applied voltage. Piezoelectric actuators are made on this property of materials. The main advantage of piezoelectric actuators is their high resolution as the extension of the material is minute for even high voltages. The same is a disadvantage also as for a minimal displacement very high voltages are needed to be supplied. Other than that piezoelectric materials hold the hysteresis property which enables the user to use it repeatedly for same results.
- Electromechanical Actuators: Electromechanical actuators are almost same as mechanical actuators. The only difference between these two is the control handle of the mechanical actuator is swapped with a motor. Other than that all structural components are more or less same. Another difference is in the positioning system of both cases. As it mentioned earlier manual markings are used for the mechanical actuator to position the set up correctly, but in case of electromechanical actuators encoders are used for more accuracy. Digital position readouts are also may be used for the same.
So these were the different types of stepper motor linear actuator which can be powered by stepper drivers too. Each of them has purposes of their own, so the usage depends mainly on the clients’ preferences.