FAQ

Q

What is notable about the use of brakes on stepper motors?

A

1. Greater operating safety on vertical axes

To prevent uncontrolled downward movement due to gravity in the event of a power failure or emergency stop, Nanotec brakes are primarily used in Z-axes for personal and property protection.

2. Safety brake and holding brake

All Nanotec brakes are holding brakes or safety brakes with two frictional surfaces (spring-applied brakes), and the brakes are ventilated or opened by applying a voltage of 24VDC. They are almost always installed on the B-bearing side of electric motors. Braking of motion is effected by the controlled drive, whose rotational speed is first reduced to zero (to a standstill) before the safety brake closes. BKE brakes are electromagnetically ventilated brakes for dry operation whose braking force is generated by permanent magnets.

BW and BL brakes are spring-force ventilated brakes whose braking force is generated by a compression spring. When no current is applied, springs push against the anchor disc of the brake. The friction linings of the rotor, which is connected to the motor shaft via toothing, are clamped between this anchor plate and the mounting surface (rear side of motor) of the brake. When current is applied to the brake coil, a magnetic field builds up that pulls in the anchor plate and releases the rotor with the friction linings. The brake is ventilated. The specified torques apply for dry operation with absolutely grease-free frictional surfaces. The torque is lower for greased frictional surfaces.

3. Emergency stop brake

The steps required to stop a system safely need to be examined and checked in the form of a risk analysis as part of a disaster management plan or machine safety program. Nanotec brakes meet the static holding torques specified in the data sheet but cannot additionally handle the often considerable dynamic loads that arise when braking a moving load. If the dynamic load is in the range of the static load on the brake (work of friction, rotational speed, kJ, duty cycle, etc.), the brake can be used as an emergency stop brake 10 times before it needs to be inspected and usually replaced. Especially in regions with unstable power supplies, power failures and emergency stops may be quite frequent (causing uncontrolled movements) and machine safety should not be underestimated in these situations.

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