Blog in Motion

Missiles operate in some of the most demanding conditions. They can experience massive heat flux when going through the layers of the earth’s atmosphere and because of the sheer speed that the missile is traveling at. With speeds in excess of 10,000 kilometers per hour, they require components that can provide reliability and precise motion under these conditions. And with the need to respond to higher demands for performance, the technology powering these missiles needs to deliver more torque and power in relation to weight.

The Low Voltage Directive defines low voltage from 50 – 1000 Vac, or 120 – 1500 Vdc, which is based on the mains voltage used to power the electrical system and ties in with specific IEC regulations on safety and risk of shock and arcing. When low voltage motors are discussed in the context of servo motors however, low voltage is focused on battery operated applications. While standard industry brushless motors are typically operated at 120 – 480 Vac, low voltage servo motors are optimized at voltages ranging for 24 – 96 Vdc. By definition, voltages in this range are considered by the IEC to be in the Extra Low Voltage (ELV) category.

All electric motors heat up during operation, which is simply a product of passing current through a coil of wire. Electric motors use copper wire to form coils that are part of the electromagnetic circuit required to produce rotation. While copper is a very good conductor, it does have resistance that causes the copper to heat up. The amount of current delivered to the motor along with the winding resistance determines how hot it gets. The nature of stepper motor operation requires full rated current to be applied at all times, which differs from a servo motor that provides only the required current to produce the desired motion.

Compared to mechanical and hydraulic presses, mechanical servo metal stamping presses use high torque brushless motors to create more complicated stampings at faster speeds. But the type of motors used—a traditional geared or chain drive system or a direct drive motor—can dramatically impact the final product.