Motor selection when maintenance isn’t an option ~ Why strategic motor selection is mission‑critical for long‑life reliability ~

From pacemakers and neural implants to deep‑space probes, opportunities for maintenance are rare and sometimes non‑existent in mission-critical devices. In such applications, a single motor failure can be catastrophic. Here, Dave Walsha, sales and marketing director at drive system supplier Electro Mechanical Systems (EMS), shares advice on how to select the right motor to balance longevity, reliability and resilience in maintenance‑free systems.

Devices installed in inaccessible or extreme environments must withstand conditions that would otherwise degrade standard components, such as miniature DC motor bearings that can seize due to dust or vibration, precision gearhead teeth that wear under high loads and encoder contacts that fail from moisture or contamination. Even brief operational interruptions can carry high costs, particularly in highly-regulated industries such as aerospace, where a single motor failure on a satellite can cost millions and be impossible to repair.

When servicing isn’t possible, predictive maintenance offers little value. Even if sensors indicate potential issues, engineers cannot intervene in remote or hazardous environments. Therefore, some motors must be able to operate reliably throughout entire lifecycles without intervention.

What maintenance-free really means

The term “maintenance-free” can be ambiguous. In most cases, it means that routine maintenance is minimised or even unnecessary over the intended operational life. For instance, brushless DC motors can operate for tens of thousands of hours without lubrication, reducing maintenance needs when installed in inaccessible applications.

Mission-critical systems are often specified with mean time between failures (MTBF) measured in hundreds of thousands, or even millions of operating hours. Achieving such resilience requires more than selecting a high-quality motor. It means engineers must evaluate the interaction of mechanical design, materials, thermal performance and operational loads – a holistic approach where every component and design choice is scrutinised for long-term resilience.

Environmental stresses, such as temperature extremes, vibration, moisture or chemical exposure, can accelerate wear, degrade insulation and increase corrosion risk. Therefore, engineers must select materials and designs that mitigate these effects from the outset, which can involve using specialised coatings, high-performance alloys and robust sealing techniques to protect the motor from harsh conditions.

Comparing motor technologies

Different motors present different advantages and limitations that engineers must consider. While brushed DC motors are an efficient, cost-effective choice for less demanding environments, their mechanical contacts are a potential failure point over extended lifetimes. Brushless DC motors, by contrast, eliminate brushes and commutators, enabling long-life operation with minimal maintenance. These motors are particularly suitable for mission-critical or inaccessible applications.

Stepper motors offer precise positional control and are ideal where accuracy is critical. However, they require careful management of torque and step resolution to prevent heat build-up or vibration, which could shorten the motor’s operational life.

For engineers, selecting the right technology usually depends on the application, environmental conditions and required life cycle, rather than nominal power ratings alone. If in doubt, consulting an experienced motor specialist can help provide valuable guidance when technical uncertainties arise.

Ensuring system reliability

Choosing a motor for a maintenance-free device starts with understanding the operational profile: the expected duty cycle, mechanical loads and environmental stresses. Accurate analysis should guide motor selection long before prototyping.

Where possible, redundancy, such as dual motors in satellite actuators or parallel pumps in industrial systems, can reduce the impact of individual component failures. However, adding redundancy increases system weight and complexity, making it even more critical to select reliable motors, as each additional component could introduce potential failure points and operational demands.

Selecting the right technology

For engineers requesting long-life performance, EMS supplies brushless DC motors designed for continuous operation with extended service life. These motors can work seamlessly alongside gearboxes that don’t require lubrication, reducing maintenance needs. For aerospace applications, the FAULHABER BX4 motor series is recommended for its long lifespan and strong performance and can operate under intense maintenance-free conditions.

In mission-critical applications, motor selection is a design decision that directly affects safety, reliability and system lifespan. Engineers must look beyond basic performance metrics and consider wear mechanisms, environmental stresses and long-term operating conditions from the outset. By taking a system-level approach and working with an experienced partner during motor selection, engineers can build truly systems that truly are maintenance-free.

Visit the EMS website to contact a member of the team about motor solutions for your next project.