Frequently Asked Questions

The lifespan of an Allient precision motor depends on the motor type and the mechanical components used in the assembly. In brushless DC systems, the motor itself is not the limiting factor because it does not rely on mechanical commutation. Instead, the primary life‑limiting components are typically the bearings and any mechanical linkages in the actuator.

A standard bearing system often has a lifespan of around 20,000 hours, although this can vary based on shaft loading, environmental conditions, temperature, humidity, and vibration. If a gearbox is part of the system, the durability of its mechanical components also affects overall lifespan.

For applications with specific lifetime requirements, Allient can perform predictive life testing. Using specialized equipment, we simulate the expected operating conditions to estimate the service life of a motor or actuator with a high degree of confidence.

Allient motors use high‑quality materials such as standard silicon steel laminations, Hiperco 50 for high‑torque designs, and both aluminum and stainless steel housings depending on environmental needs. They are available with standard neodymium magnets as well as premium high‑energy magnet grades for higher torque density. Most models use precision ball bearings, with premium bearing options available for higher loads or extended service life.

Allient motors are deployed in an exceptionally wide range of environments, from everyday industrial settings to some of the most extreme conditions in the world. Our products operate in space, down‑hole energy applications, on‑highway and off‑highway vehicles, cleanrooms, operating rooms, military environments, underwater systems, launch platforms, high‑altitude locations, and both very low and very high temperature environments.

Every application is reviewed by our Solutions Center to determine the specific environmental requirements. This allows us to identify the materials, sealing methods, coatings, and design accommodations needed for the motor to perform reliably and safely in its intended environment.

Allient reduces vibration and noise by selecting the motor topology that best fits the speed and torque requirements of the application. Because we offer a wide range of motor configurations, from rotor‑stator part sets to fully integrated actuators, we can match the architecture to the performance needs of the system.

For applications where low noise and low vibration are essential, minimizing mechanical linkages is especially important. Direct drive solutions often provide smoother and quieter operation compared to housed motors paired with multi‑stage gearboxes. Ensuring the motor is properly matched and electrically compatible with the drive also helps eliminate audible noise and unwanted vibration.

Allient provides a wide performance envelope to accommodate everything from surgical robotics to heavy industrial machinery. Across their various product lines, the performance ranges are:

• Rated Torque: 0.006 Nm to 1,875 Nm
• Rated Speed: 40 RPM to 101,500 RPM

Using a CAD model, assuming materials properties are correct, you can extract the system’s inertia. Then you can determine how quickly your load will need to accelerate. Once you have this acceleration rate defined and your inertia, you can determine the torque required purely for acceleration (Torque = Inertia * acceleration). Friction is much more complicated. If there is an existing or similar system you can put a torque wrench on it, if not you need to use information from bearing suppliers, which tend to be conservative. Total torque is typically covered by summing these two. There is occasionally viscous friction (damping) torque, which is similar to windage torque that is present and is proportional to speed as the motor travels through a fluid medium (air, water, etc.).

No. A motor with cogging torque will always have torque ripple when running. A motor without cogging torque (slotless or air-core motor) may still exhibit torque ripple if the phases are not balanced in amplitude and phase relationship, and the torque versus angle curves is not sinusoidal with low harmonic content. It can also happen if current waveforms from the driver are not well controlled sinusoids. If a six state older style motor controller/driver is used, any motor will exhibit torque ripple.

Most motors have a torque constant you can find in a datasheet. This is only first order approximation for the torque output as a function of current. In reality, many motors experience saturation at higher currents levels, which results in less torque output per current input. This is called torque linearity. It is not shown on datasheets, but it can impact system performance and make your control system very non-linear. Only Air-Core motors and slotless motors have good torque linearity up to current levels well above the continuous rated current.

Most motors have a continuous torque rating. This rating was derived under some thermal test conditions at the supplier. Rated torque is the least understood and the most corrupt parameter for any motor. Heat is the enemy of torque. Know the test conditions that a particular motor was rated at and make an engineering judgement whether you can use those ratings. It is recommended to avoid using these ratings unless the test conditions were exactly like your project (never the case). Torque rating is a reference point only. Thermal modeling is difficult and needs empirical input to be useful. Many solid modeling software tools have a thermal FEA module this can help determine the likely thermal resistance of the system you are developing. Peak torque rating should not be used until you know how close the motor torque output is to your needs.

Start by understanding your application’s duty cycle, including the difference between continuous and peak operation. This helps ensure the motor is sized to stay within its thermal limits. The motor constant (Km) is also useful for estimating how much heat is generated for a given torque.

If the motor is running near its thermal limits or space is tight, additional cooling may be needed. Common options include forced‑air cooling, liquid cooling, or improving the thermal path with heat‑conductive mounting surfaces.

These methods help remove excess heat, maintain stable operating temperatures, and extend motor life in high duty cycle or high torque applications.

Typical ranges for motors are -50 to +150C. This means that the motor supplier will use materials that are rated above or below these to achieve a safety factor. If there is an encoder in the system the limits may change from operation at 0C to 80C due to limits on the encoder, depending on where it is in the system. Bearings are limited by colder temperatures, as standard lubricants may thicken and solidify. Electrical insulation systems and magnets can be chosen to operate over 200C if the rest of the mechanical systems can handle this temperature.

Our motors can operate in a vacuum or space environment, but we must take some extra steps to ensure the motor can operate as it should. Things like off gassing, thermal load, and material selection must be considered. Some materials like plastic, adhesive, or potting materials will release gasses (known as off gassing) in a vacuum, which could deposit on surfaces or cause issues, so swapping materials may be required. Due to the absence of convection, thermal management must also be analysed, otherwise the motor could overheat.

Our motors can operate in a vacuum or space environment, but we must take some extra steps to ensure the motor can operate as it should. Things like off gassing, thermal load, and material selection must be considered. Some materials like plastic, adhesive, or potting materials will release gasses (known as off gassing) in a vacuum, which could deposit on surfaces or cause issues, so swapping materials may be required. Due to the absence of convection, thermal management must also be analysed, otherwise the motor could overheat.

In vacuum there is no convection, only conduction. This means the physical mount and material used is critical to heat flow. Smaller motors rely on conduction more so than large motors with lots of surface area that use more convection. So, if it is a small motor <50mm diameter then its derating in vacuum would be less. A large motor >50mm would require a more significant derating. General rule of thumb would be to assume 50% of the heat transfer available (under nominal operating conditions). This means that the motor would be derated to 75% of the torque output because power is mainly a function of copper losses which are proportional to the square of the current.

Eddy currents in a motor are related to the rate of change of the magnetic field in the iron. They appear as a damping term in simulation modeling, such as Nm/rad/sec. Motor designers typically laminate the magnetic structure to minimize the flow of eddy currents. Thinner laminations provide a higher resistance to eddy current flow. Any eddy currents present will produce heating in the motor and result in a drag torque that is proportional to speed.

Yes. Hysteresis in the motor laminations is caused by the changing magnetic fields as the motor rotates. Motors with high levels of magnetic flux will have higher hysteresis. Motor or transformer grade steel with high Ni content is typically chosen to minimize magnetic hysteresis. Hysteresis is a friction term if you are doing any modeling. Most motors have hysteretic friction. The higher-performance motors with higher strength magnets have higher hysteresis. There are some trends moving away from laminations to SMC (sintered metal compound) materials.

Linear motors produce motion in a straight line rather than a circular motion, and they provide the power for transporting from point A to point B, such as a conveyor belt or railroad track. Linear motors are also a solution for actions requiring speed control. They are often used in semiconductor, print and science industries, where they help perform measuring and testing tasks.

Allient’s servo drives improve performance by using high‑speed 20 kHz control loops that deliver smooth, precise torque, speed, and position control. Advanced encoder processing increases feedback accuracy, which enhances motion quality in robotics and precision automation. The drives also integrate easily into PCB boards, control panels, multi‑axis systems, and motor assemblies, helping OEMs build compact and efficient motion platforms. Allient’s design and integration services further boost performance by optimizing hardware, tuning control loops, and reducing engineering effort for faster system development.

Km is related to the cross-sectional area of copper in the motor. When winding turns are reduced to increase speed, resistance will change if the wire size is not adjusted. However, different wire gauges are typically used so the copper fill remains the same. As a result, Km does not change with winding scaling, although small variations can occur.

KE is the back EMF constant and represents the voltage generated by a motor at a given speed. KT is the torque constant and describes how much torque is produced for a given current. For permanent magnet motors, KE and KT are equal when the units are consistent. KE is expressed in volts per radian per second, and KT in newton meters per ampere. KT can be used with resistance to calculate Km. It is important to ensure correct unit consistency when using these values, as datasheets may present them in different formats.