In addition to the step motor itself, there may be other requirements that necessitate the use of an encoder, an electromagnetic brake or a terminal box on the step motor. For example, an encoder detects the missteps under load, a brake keeps the motor shaft in its position in case of a voltage drop and a terminal box offers the possibility to operate the step motor with a special cable, which is designed for locations with higher requirements.
Step motors with terminal box and an M16 gland for the cable inlet are used wherever a terminal box is advantageous due to the ambient conditions. E.g. in the food industry, on machine tools or on packaging machines. Applications for these step motors can also be found in medical technology, in laboratory technology for dialysis equipment and analysis devices or in general mechanical engineering. For example, shielded cables (for EMC shielding) highly flexible cables or even oil-resistant cables can be used as supply cables.
In the event of a sudden voltage drop / power failure, electromagnetic brakes ensure that the position, e.g. of the Z-axis, is held to prevent damage to tools and workpieces. The holding torque of the brake is generated by the use of a compression spring. Here, in the event of a voltage drop / power failure, a so-called stroke, which is firmly connected to the rear motor shaft (B-shaft), is held in position by a compression spring. To release the motor shaft, a 24 V DC voltage must be applied to the brake. This voltage excites an electromagnet, which then releases the pressure spring of the brake, so that the motor shaft can rotate freely again. Typical applications would be e.g. the Z-axis (vertical axis) of a milling machine. Here, the brake holds the motor and the milling head mounted on it in its current position so that it does not fall onto the workpiece and damage it in the event of a power failure.
An encoder is also referred to as an angle of rotation encoder or rotary encoder and is a sensor that detects the angle of rotation / step angle of a step motor. The steps detected by the sensor are evaluated by the upstream control electronics. In the case of a step motor with encoder, the encoder ensures that the motor is in the desired position. It can be used to detect faulty steps and, if necessary, to take corrective action. Step motors work with defined step angles / degree steps, which are referred to as single steps. A 2-phase step motor, for example, can perform between 200 steps and up to several thousand microsteps until a complete revolution is achieved. Thanks to these very small individual steps, step motors can be controlled very precisely and work very accurately. However, external forces, when the load torque is greater than the torque or holding torque, can cause inaccuracies and even step losses. That is, "the motor gets out of step" it loses or skips individual steps. The more often this occurs, the less accurate the positioning becomes. An encoder is used to detect this error or to build up a close-loop system by means of an actual-target comparison.