I'm a quality manager at a motion-control integrator. I review motor lots, custom configurations, and field returns before they get approved or released—roughly 4,000 units per year. In 2024 I rejected about 5% of first-article deliveries because the supplier couldn't prove the torque constant at our test voltage. So, when I talk about motor selection and motor failure, that's the perspective I'm coming from.
There is no single best motor in the maxon-motor catalog or in any other catalog. The right choice depends on your motion profile, your duty cycle, your controller, and how expensive a failure will be. A cheap motor that fails during a customer demo is not cheap. I'll split this into four scenarios, then talk about linear actuator failures because that's often what people search for when it's already too late.
If You Need Compact Precision and Closed-Loop Control
This is what a maxon DC motor Swiss made line is built for. When an engineer writes "maxon DC motor Swiss made" in a specification, they are not just asking for a country of origin. They're asking for a tolerance culture: tight commutation, traceable test data, and a torque-speed curve that doesn't lie.
In our Q1 2024 quality audit, we checked 214 motor lots from three manufacturers. The Swiss-made maxon samples had zero torque rejections. The best "equivalent" we tested had a 9% rejection rate on measured torque at 24 V. That is the kind of difference you don't see on paper. You see it later, in a field failure or in a motion profile that isn't as smooth as the simulation promised.
If you need continuous rotation, low cogging, and smooth speed control inside a small package, a maxon DC motor or a maxon BLDC motor with an encoder is the dependable route. It costs more upfront, and it often pays for itself in fewer service calls. For most custom machinery, I start in the maxon-motor range only after I've confirmed the load and speed. Their datasheets show torque constants, terminal resistance, and thermal limits at several voltages—which is more useful than a generic "high performance motor" claim.
According to maxon's published documentation, continuous torque is defined at a specific winding temperature and ambient condition. Ignore the mounting plate requirement and the torque number becomes fiction. One warning: continuous torque is not the same as peak torque. I've seen teams pick a motor by its peak stall torque and ignore the thermal curve. That is the fastest way to get smoke. If your duty cycle is 100%, use the continuous torque number and add a safety margin for ambient temperature.
If You're Doing Point-to-Point Positioning on a Budget
Look, if your requirement is ±0.5 mm and you are not fighting a heavy inertia load, a stepper is not a dirty word. A maxon stepper motor with a home switch—or a magnetic encoder if you want feedback—can handle a surprising amount of automation. The old "steppers lose steps" fear comes from an era when steppers ran open-loop with no encoder and no current control. That's changed.
The motor is simple—or rather, simple to use, but not always simple to specify. Steppers run hot by design. If your enclosure is sealed and the ambient temperature is 40 °C, the motor's continuous torque rating drops dramatically. The same applies to any motor, but steppers catch more blame because they are expected to hold position at standstill, which means full current in many controllers. If you go this route, budget for the right driver and check the winding temperature.
If you add an encoder to the stepper, you get the main benefit of a servo—position error detection—without the full servo tuning effort. That is often the right middle path.
If It's a Pump, Fan, or Continuous High-Speed Load
Take motor size first. Above roughly 1 kW of continuous shaft power, a 3 phase AC motor with a VFD is usually the right answer. It's not a competitor to maxon-motor; it's a different class of machine. A 15 kW pump is not where you put a small Swiss-made DC motor.
The reverse mistake shows up too: putting a 3 phase AC motor into a precision tool where it has to follow rapid position commands. That works about as well as using a truck to tow a bicycle. The scenario matters. If you need high speed and high power with modest positioning accuracy, a 3 phase AC motor has the widest supply chain and the cheapest repairs. If you need precision, don't force it.
AC induction motors are also more forgiving of unknown loads than small DC motors, as long as the thermal protection is set correctly. But the rotor inertia is high. In a high-acceleration positioning axis, that inertia mismatch will hurt more than any motor brand name.
If a FANUC Servo Was Working and Then Stopped
This is a different situation. A fanuc servo motor repair decision isn't a motor selection problem; it's an asset management problem. Before you authorize a repair, get the drive alarm history. FANUC drives store alarms, and one of my first questions is always: did the drive trip on overcurrent, encoder loss, or DC link? The answer changes the root-cause hunt.
I'm not a repair tech, and I don't pretend to be one. But over the last five years I've reviewed close to 200 repair quotes—actually, that number is over 300 now. Here's the rule: a repair quote should come with a before and after test report. That includes winding resistance, insulation resistance, and a loaded vibration test at the motor's rated speed. If a fanuc servo motor repair shop says "we know what we're doing, trust us," treat that as a red flag. Send it somewhere else.
When the repair quote is above 60% of a new equivalent motor, replace it. When the encoder is damaged or the motor is obsolete, replace it. When you need the machine back in 72 hours and a replacement is on a 6-week lead time, repair—but only after the test report looks right.
Oh, and check the encoder connector before you send anything out. I've annotated two repair cases where the motor was fine and the connector pin was the actual failure. That is a $50 fix, not a $500 repair.
What Happens When a Linear Actuator Fails
Let's answer the question directly: what happens when a linear actuator fails is not always dramatic. Sometimes it just drifts a few millimeters. Sometimes it jams and triggers an overcurrent alarm. Sometimes it makes a grinding noise and keeps moving until the limit switch finally breaks. The failure mode decides whether you repair, replace, or just recalibrate.
First, isolate the symptom:
- No motion at all: check the controller, the brake (if installed), and the motor winding continuity before blaming the actuator.
- Position drift: check the encoder or limit switch, then check backlash in the screw/nut. In my experience, drift is more often mechanical wear than an electrical fault.
- Overcurrent trip: do not assume the motor is shorted. We had a returned actuator where the customer's mechanical stop had been removed; the screw jammed at the end of travel and the motor stalled against it. The winding was fine.
- Burning smell or high temperature: check duty cycle. A maxon DC motor Swiss made unit can fail—rarely—but when it does, it's almost always because the application exceeded the rated continuous torque without the specified heat sink.
People assume a burnt motor caused the machine failure. Often it's the effect of an increasing mechanical load or a failed gearbox. The causation runs the other way. The motor stalled because something else jammed. A linear actuator is a system: motor, gearbox, screw, nut, limit switches, and controller. When it fails, the first component that burns is rarely the root cause.
How to Tell Which Scenario You're In
Ask yourself these questions, in this order:
- Does the load rotate continuously or move from point to point? Continuous usually favors AC or BLDC; point-to-point can favor stepper or servo.
- How precise must position be? If you need feedback and high acceleration, that's a servo/encoder solution, not a simple stepper.
- What's the ambient temperature? Thermal derating changes every recommendation.
- What is the cost of one hour of downtime? If it's $10,000/hour, don't choose a motor based on a $200 price difference.
I can only speak to indoor industrial installations. If you're putting a linear actuator outside, in a washdown area, or on a coastal structure, salt and moisture change the entire calculation. The same hardware that works beautifully indoors may fail in a month outdoors.
"This isn't our strength—here's who does it better." That sentence earned my trust for everything else.
That applies to motor brands as much as to integrators. A vendor who tells you what they can't do is more credible than one who says yes to everything. Use the scenario, not the brand, as the starting point. For compact precision, a maxon DC motor Swiss made line is hard to beat. For budget positioning, a maxon stepper motor with feedback works. For continuous power, a 3 phase AC motor is often the sensible workhorse. For a fanuc servo motor repair, get the test data before you spend money. And when something stops moving, find the failure mode before you replace the part.