Guides
Technology comparisons
Side-by-side comparisons of competing technologies, with tables, worked examples and clear guidance on when to choose each.
Slip rings
- Capsule vs through-bore vs pancake slip ringsPick a capsule slip ring when nothing has to pass through the centre and space is tight; a through-bore ring when a shaft, cable or fluid line must run through the axis; and a pancake (platter) ring when the axial height is very limited but there is room radially.
- Contact vs contactless slip ringsChoose a contact slip ring for power, mixed circuits and moderate data at the lowest cost; it is the only practical way to pass kilowatts.
Linear actuators
- Ball screw vs roller screwA ball screw is the cheaper, slightly more efficient choice for moderate loads and smooth motion.
- Rodless actuators: belt drive vs ball screwChoose a belt-driven rodless actuator for long strokes and high speed (Tolomatic quotes up to about 5 m/s and strokes beyond 5 m), and a ball screw for thrust, stiffness and accuracy on strokes up to about 1–3 m and speeds up to about 1.5 m/s; then size the guidance for the cantilevered payload's moments, not just its weight.
Servo and stepper motors
- Brushed vs brushless motorsChoose a brushed DC motor when running hours are modest (maxon puts typical brush life at 1,000 to 3,000 hours), the electronics must be minimal and cost per unit matters.
- Servo vs stepper motorsChoose a stepper for low-to-moderate speeds (roughly under 1,000 rpm), modest inertia and simple point-to-point moves where cost matters; a closed-loop stepper removes the risk of silently lost steps.
Frameless and torque motors
- Frameless vs housed motorsUse a frameless rotor and stator kit when the motor can become part of your machine's structure, sharing its bearings and housing, and you need the shortest, lightest and stiffest axis with a hollow centre.
Gearboxes and harmonic drives
- Planetary vs worm vs bevel gearboxesUse a planetary gearbox for inline servo axes needing high efficiency, low backlash and high torque density; a worm gearbox for low-cost, quiet right-angle drives at modest duty where low efficiency is acceptable; and a spiral bevel or hypoid stage, usually combined with planetary stages, for right-angle servo axes that need planetary-class efficiency and precision.
- Strain-wave vs planetary vs cycloidal gearboxesChoose a strain-wave (harmonic) gear for compact, zero-backlash joints needing 30:1 to 160:1 in one stage; a precision planetary for ratios below about 30:1, high efficiency and lower cost; and a cycloidal reducer when the axis needs high torque, high stiffness and the best tolerance of shock and tilting loads.
Encoders and feedback
- Absolute vs incremental encodersUse an absolute encoder when the machine must know its position at power-up without moving, which is most servo axes, robot joints and anything that cannot safely home.
- Magnetic vs capacitive vs optical encodersOptical encoders give the highest accuracy and resolution but need a clean optical path and tight mounting.
Controllers and PLCs
- EtherCAT vs PROFINET vs EtherNet/IP for motion controlAll three can run synchronised multi-axis servo motion.
- PLC vs motion controller vs industrial PCUse a PLC when the machine is mostly logic and I/O with a few simple axes; a motion controller (or motion-capable CODESYS PLC) when several axes must move together with gearing, cams or interpolation; and an industrial PC when the same box must also run vision, data handling, HMI or custom code alongside real-time control.
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