What are the application advantages of stepper motors?
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Stepper motors are digitally controlled and regulated drives that have achieved the highest level of acceptance and prevalence since the technology transition (from analog to digital technology and current software solutions) due to favorable prices with maximum service life and little control required.
a) PC+PLC-capable (directly controllable via PC, PLC and microprocessor).
The use of the PC at the lowest, decentralized machine levels has given the Plug & Drive motors the maximum level of productivity. Nanotec was the No. 1 supplier worldwide to fulfill the requirement for a compact, efficient and cost-effective drive system with an industrial Plug & Drive motor. Not only have the development, wiring and assembly costs of a complete drive unit been drastically reduced, the EMC compatibility and machine availability have been improved, and the commissioning and service also considerably simplified. Continuous further development of the options for customer-specific requirements allow new and close partnerships to grow constantly to the advantage of a better and more economical end product.
b) Speed stability
“No drop in speed when the load fluctuates”: The stepper motor fulfills this requirement like no other motor at no extra cost. Particularly for precise closed-loop speed, synchronization or ratio controls (e.g. in precision dispensing pumps), the stepper motor can reach higher and finer resolutions thanks to digital processing. The improvement in control, process and surface quality is not only a theoretical advantage.
c) Direct drive
Stepper motors have maximum torque in the lower speed range and the Nanotec microstep drives enable still acceptable concentricity properties up to approx. 2 rpm. Other motors often need gears for this purpose in order to fulfill the requested speed and force requirements. Direct drives reduce system costs and, at the same time, increase operational safety and life expectancy. Naturally, if the space available is limited or the external moments of inertia are high, gears are essential for power and force adjustment.
d) Avoiding damage to machines and injuries
The disadvantage sometimes referred to as the "loss of sync." where a motor is blocked can even be an advantage in some cases in light of constantly increasing safety requirements. Sliding clutches and overload clutches in order to meet prescribed safety requirements are not normally necessary in association with stepper motors.
e) Positioning accuracy
As well as minimum coastdown, stepper motors also have a minimum transient response because of the narrow step angle. Even without external linear or angular encoders, stepper motors are excellent at fulfilling speed and positioning tasks. The microstep changeover of the Nanotec final output stages can, in fact, further increase the accuracy or resolution at no extra cost. All Nanotec stepper motors are also available with competitively priced encoders for detecting any blockages as well as for closed-loop applications.
f) High stiffness without brake
Stepper motors have the maximum holding torque at a standstill and thus also offer high system rigidity. Because of this property, no external braking mechanism is necessary unless safety braking is required for the Z axis. Even for normal stopping, the stepper motor can be advantageous. When a servomotor is stationary, the closed-loop control must operate at full speed. The drive control oscillates with a slight back and forth around the selected null point. In most applications this is of no consequence. When positioning a mirror for a metrological task that deflects a laser beam, for example, this oscillation can however quickly become disruptive. On the other hand, the stepper motor would simply move to its position here and stay still.
g) Highly dynamic
Primarily in conjunction with the new dynamic closed loop SMCI .. positioning control as well as PD6.. Plug & Drive motors up to a speed of approx. 2000 rpm, stepper motors achieve higher dynamics and angular acceleration than servomotors due to the high number of contacts, the low rotor mass and the small air gap. This has a primarily favorable effect wherever small distances and movements must be positioned or reserved ultra fast and, at the same time, with an extremely small settling time or transient response such as required in semiconductor technology, optics and also in textile machinery and testing machines.
h) Easy controllability
Drive solutions using stepper motors can be realized very easily and cost-effectively because they can be realized in an open loop, i.e. without external encoders. In addition to the motor, the power electronics (drive) and an appropriate power supply are required. An external time base (PLC, PC or simple RC oscillator) can take on the speed or position. The clock pulse could be specified with a small additional board, even via an analog input (0-10V, 0-5V or +/-10V) or potentiometer, and hence would be controllable similar to a BLDC motor.
