Voice coil motors and actuators for optical focusing, scanning, valves, ultrasonic welding and precision positioning · moving coil vs moving magnet, stroke, continuous and peak force, force constant and motor constant, acceleration, feedback resolution, servo amplifier, environment
A voice coil motor (VCM), or voice coil actuator, is the simplest electric linear motor: a coil in a permanent-magnet field moves in proportion to the current through it, giving fast, smooth, short-stroke motion and force control without gears. Makers list them for optical focusing, scanning, valve control, ultrasonic welding and precision positioning. Ask three things first: the stroke and force — continuous and peak — needed with your moving mass; whether a moving-coil or moving-magnet design fits the space and wiring; and what feedback, bearing and servo drive the system will use.
Voice coil motors and actuators — linear moving-coil and moving-magnet types, cylindrical and rectangular, with or without integral bearings, shafts and position sensors, and hollow-core designs. Linear stepper and multiphase linear servo motors, loudspeaker voice coils, solenoids and complete camera modules are outside this page except where compared.
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01
H2W Technologies, a voice coil actuator maker, explains that the actuators work on the Lorentz force: a current-carrying conductor in a magnetic field experiences a force proportional to the current and flux density, so with a fixed permanent-magnet field the direction of motion follows the current's polarity and the force is directly proportional to it. Wound so that no commutation is needed, they suit short-stroke (H2W cites under 2 inches) closed-loop servo applications, with low electrical and mechanical time constants and low moving mass for high acceleration of light payloads, and their linear force-current relationship allows precise force control. Typical non-commutated actuators offer 0–75 mm (0–3 in) stroke, accelerations up to 20 g, continuous force up to 450 N (100 lb) and peak force up to 1,350 N (300 lb), and position resolution down to 0.1 µm with a linear encoder or LVDT. Longer strokes are possible but the motor constant (Km) is inversely proportional to stroke, so efficiency falls; for longer strokes the coil can be wound multiphase and commutated. [1]
Editorial calculation: in that typical range the peak force is three times the continuous force (1,350 ÷ 450 N), so ask the supplier how long and how often peak force may be applied, and check that the force needed for the sustained part of your cycle stays within the continuous rating. [1]
A published single-model specification shows how these quantities fit together. Stanford Magnets lists its rectangular voice coil actuator 0020-035-000 with a 35.0 mm stroke, 0.5 mm coil gap, 21.1 N peak force, 8.1 N continuous force, force constant 5.8 N/Arms, back EMF 5.8 Vrms/(m/s), peak current 3.6 A, peak voltage 20.9 V, motor constant 2.4 N/√W, phase resistance 5.7 Ω, phase inductance 1.6 mH, electrical time constant 0.28 ms, maximum winding temperature 155 °C, mover weight 40 g, total weight 480 g and dimensions 68 × 35 × 60 mm. [3]
Editorial calculation from those listed values: force constant ÷ √resistance = 5.8 ÷ √5.7 ≈ 2.4 N/√W, matching the stated motor constant; inductance ÷ resistance = 1.6 mH ÷ 5.7 Ω ≈ 0.28 ms, matching the stated electrical time constant; and peak force ÷ force constant = 21.1 ÷ 5.8 ≈ 3.6 A, matching the stated peak current. Use the same three checks on any quotation datasheet. [3]
Give the supplier the stroke, continuous and peak force, moving mass and payload, required acceleration and move time, force constant or current limit, supply voltage and drive, moving-coil or moving-magnet type, bearings and shaft (supplied or not), position feedback and resolution, size envelope (cylindrical, rectangular, hollow core), lead length and connector, operating temperature and environment, and quantity.
02
H2W describes moving-coil actuators as supplied without bearings or shaft as standard, larger in diameter and shorter, gaining force with diameter and able to have large radial clearances so the coil never touches the magnet; moving-magnet actuators come with bearings and a shaft, are smaller in diameter and longer, gain force with more poles or diameter, and have no moving leads because the coil is stationary. Because of their very low inductance they need a DC linear servo amplifier, with a programmable motion controller closing the position loop, and they should not be mounted in wet or very dirty places or above 50 °C ambient. For moving-coil units without bearings the purchaser must supply bearings that keep the coil centred, since contact between coil and magnet assembly can follow. [1]
Moticont describes voice coil motors as two separate parts, a magnetic housing and a coil, that move in one direction with applied voltage and reverse with polarity, reaching positioning accuracy below one micron with a position sensor. It offers types without internal bearings, types with an internal shaft, long-life linear bearings and integrated position sensor, and hollow-core motors with a large axial hole suited to optical focusing, scanning and precision positioning. [2]
03
Akribis Systems publishes a model table for its AVM High Force series of cylindrical moving-coil voice coil motors, from 14.2 mm to 250 mm diameter and 4 to 35 mm effective stroke. It lists continuous force, peak force, coil weight and total weight for each model, and describes the series as direct-drive with zero cogging and zero backlash, no contact between coil and core, and resolution that depends on the feedback device. Selected rows: [4]
Editorial calculation from the table: peak force runs 3.0 to 5.0 times continuous force in these rows (16.3 ÷ 5.44 ≈ 3.0; 23.9 ÷ 4.8 ≈ 5.0) and 2.1 to 6.4 times across the full table (AVM130-HF-25 to AVM30-HF-4), so size the motor on the RMS force of the duty cycle and use the peak only for short moves. Peak force divided by coil mass gives the bare-coil acceleration ceiling: about 1,207 m/s² (123 g) for the AVM20-HF-6 but about 328 m/s² (33 g) for the 35 mm-stroke AVM20-HF-35, whose coil is 5.4 times heavier at the same 20 mm diameter. Any payload and bearing mass lowers these figures. [4]
The same-diameter comparison shows the trade-off H2W describes: a longer stroke adds coil mass without adding continuous force. [4] [1] Ask for the force-stroke curve, since the table's figures are single ratings over the effective stroke.
| Model | Diameter (mm) | Effective stroke (mm) | Continuous / peak force (N) | Coil / total weight (g) |
|---|---|---|---|---|
| AVM14-HF-5 | 14.2 | 5 | 2.27 / 6.81 | 7 / 13.7 |
| AVM20-HF-6 | 20 | 6 | 5.44 / 16.3 | 13.5 / 47.5 |
| AVM20-HF-35 | 20 | 35 | 4.8 / 23.9 | 72.9 / 150.4 |
| AVM50-HF-20 | 50 | 20 | 50 / 208.5 | 195 / 931.1 |
| AVM100-HF-30 | 100 | 30 | 309.5 / 1,241.9 | 2,012.9 / 5,485.7 |
| AVM250-HF-20 | 250 | 20 | 1,111.4 / 4,715.2 | 5,900 / 27,200 |
04
Suppliers linked to this page list voice coil motors; each card links to the page reviewed.
Listings include cylindrical and rectangular linear voice coil motors with stated stroke and peak force, models for valve control and ultrasonic welding, and voice coil motors alongside stepper and linear stepper motors; ask each for force-stroke curves, force constant, thermal limits and test data.
05
This is a functional reference built from the sources cited; it is not one maker's design.
| Element | Role | Fix in the order |
|---|---|---|
| Magnet assembly | Fixed flux field. [1] [2] | Size, poles. |
| Coil | Force ∝ current. [1] | Resistance, Kf. |
| Bearings and shaft | Keep coil centred; may be customer-supplied. [1] | Supplied or not. |
| Position sensor | To 0.1 µm with encoder/LVDT. [1] | Type, resolution. |
| Servo amplifier and controller | Needed for low-inductance coil. [1] | Drive, controller. |
06
A voice coil motor quotation needs values for your project. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Stroke length (mm) | 0–75 mm in H2W's range. [1] 4–35 mm effective stroke in another maker's cylindrical series. [4] | Stroke. |
| Peak force (N) | Up to 1,350 N typical range. [1] 6.81–4,715.2 N across one cylindrical series. [4] | Peak, duty limit. |
| Force constant (N/A) | Force ∝ current; 5.8 N/Arms on one model. [1] [3] | Kf, Km. |
| Coil resistance (Ω) | 5.7 Ω phase resistance, 1.6 mH inductance on one 35 mm-stroke model. [3] | Resistance, inductance. |
| Rated voltage (V) | 20.9 V peak voltage at 3.6 A peak current on one model. [3] | Voltage, current. |
| Position accuracy | <1 µm with sensor; 0.1 µm resolution. [2] [1] | Feedback, accuracy. |
| Response time | Low time constants; 0.28 ms electrical time constant on one model. [1] [3] | Bandwidth, move time. |
| Operating temperature (°C) | Avoid >50 °C ambient (one maker). [1] | Range, thermal limit. |
| Ingress protection | Not for wet or dirty sites. [1] | Sealing. |
| Weight (g) | 40 g mover, 480 g total on one model. [3] | Moving and total mass. |
| Dimensions | Cylindrical, rectangular, hollow core. [2] | Envelope. |
07
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Motion: [stroke; move time; acceleration] Force: [continuous; peak; duty cycle] Mass: [moving mass; payload] Type: [moving coil; moving magnet; hollow core] System: [bearings; feedback; servo drive] Environment: [temperature; dust; moisture] Quantity: [units]
These companies list voice coil motors.
Lists cylindrical and rectangular linear voice coil motors, including models for valve control and ultrasonic welding.
Product scope checked 2026-10-11
Lists voice coil motors alongside stepper, linear stepper and can-stack motors.
Product scope checked 2026-10-11
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
By the Lorentz force: a current-carrying coil in a magnetic field feels a force proportional to the current, with direction set by its polarity. [1]
H2W cites 0–75 mm stroke, up to 450 N continuous and 1,350 N peak, and up to 20 g acceleration for non-commutated actuators. [1]
Moving-coil units are wider and shorter and come without bearings as standard; moving-magnet units include bearings and a shaft and have no moving leads. [1]
Divide force constant by the square root of coil resistance to get motor constant, and inductance by resistance to get the electrical time constant; on one published model 5.8 N/Arms and 5.7 Ω give about 2.4 N/√W, and 1.6 mH ÷ 5.7 Ω gives 0.28 ms (editorial calculation). [3]
It varies by model: in Akribis' AVM High Force table the AVM50-HF-20 lists 208.5 N peak against 50 N continuous, about 4.2 times (editorial calculation from the listed values). [4]
Sources checked 2026-10-11. H2W Technologies, Moticont and Akribis Systems are voice coil actuator makers describing their own products and the operating principle; a Stanford Magnets single-model specification supplies example electrical and mechanical values.
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