Magnetostrictive Position Sensor for Hydraulic Cylinders — SSI, 4-20mA, 350 bar
SEGMENsensor magnetostrictive linear position sensors are designed for direct installation inside hydraulic cylinders, providing absolute position feedback on ram extension. Welded into the cylinder end-cap or rear port, the sensing rod extends through the cylinder bore. Rated to 350 bar (5,000 PSI) working pressure. Output: SSI, CANopen, Profibus, 4-20mA, Start/Stop. Stroke 50–4,000 mm. Accuracy ±0.05 mm. IP67, CE certified, OEM from 10 pcs.
What is a Magnetostrictive Position Sensor for Hydraulic Cylinders?
A magnetostrictive position sensor for hydraulic cylinders provides absolute, non-contact linear position measurement of the cylinder ram (piston rod). The sensor consists of a stainless steel sensing rod installed through the center of the hydraulic cylinder piston, and a position magnet mounted in the piston. The waveguide inside the rod uses the magnetostrictive effect — a torsional ultrasonic pulse returns to the head electronics when the magnetic field of the piston magnet intersects the current pulse. Time-of-flight measurement gives absolute position with ±0.05 mm accuracy, no calibration required, even after power loss.
Technical Specifications
Hydraulic Cylinder Magnetostrictive Sensor — Full Spec Table
All parameters for SEGMENsensor in-cylinder magnetostrictive rod sensors. Custom stroke, output interface, and connector on request.
Technical and commercial questions on mounting, pressure ratings, output interfaces, and OEM supply.
How does a magnetostrictive sensor mount inside a hydraulic cylinder?
The most common installation is through the cylinder rear end cap: a threaded port (typically G1/2" or NPT 1/2") is machined into the end cap. The sensor rod screws into this port and extends through the hollow piston rod, with its tip resting in a blind bore in the piston face. A position magnet ring is pressed or bonded into the piston bore around the sensor rod. As the piston strokes, the magnet moves with it along the stationary rod, and the sensor electronics in the head detect the magnet's absolute position. No seal is needed on the rod itself — the process seal is only at the end cap port.
What pressure rating do I need for a hydraulic cylinder position sensor?
SEGMENsensor standard magnetostrictive rod sensors are rated for 350 bar (5,000 PSI) working pressure with pressure spikes to 700 bar. This covers most industrial hydraulic applications (typical system pressure 150–250 bar). For high-performance servo hydraulics operating at 280–350 bar, confirm the rod end connection is rated for your nominal pressure. For ultra-high pressure (>350 bar), request our heavy-duty version with reinforced end cap seal. Always specify your nominal and peak system pressure when requesting a quote.
What is SSI output and why is it used in hydraulic cylinder sensors?
SSI (Synchronous Serial Interface) is a point-to-point serial protocol widely used in absolute encoders and magnetostrictive sensors. It transmits the absolute position value as a binary word over a differential RS-422 link (clock + data pairs) at update rates up to 100 kHz. Advantages over analog (4-20mA): immune to electrical noise in hydraulic press environments; 25-bit resolution (sub-micron); no signal drift over cable length. Connects directly to servo drives, motion controllers, and PLC SSI modules. SEGMENsensor supports both Gray code and binary encoding, 24 or 25 bits.
Can the same sensor output both SSI and 4-20mA simultaneously?
Not simultaneously from a single output port. However, SEGMENsensor offers dual-output models with one SSI port (for the servo drive) and one 4-20mA output (for the PLC analog input or display), both derived from the same measurement simultaneously — useful when you need both position feedback for the drive and a process display or safety shutdown based on the same sensor. Specify "dual output SSI + 4-20mA" when requesting a quote. Standard single-output models come with SSI, Start/Stop, 4-20mA, or CANopen — select one at order.
What position magnet do I use with a hydraulic cylinder magnetostrictive sensor?
SEGMENsensor supplies matched position magnets for each sensor series. Standard: ring magnet, rare-earth (NdFeB) or ferrite, bore diameter matched to sensor rod OD (typically 10, 12, or 16 mm). The magnet is press-fit or retained by a groove in the piston bore. Minimum magnet-to-rod clearance: 0.5 mm radial air gap all around. Never use ferrous (iron) parts within 5 mm of the magnet-rod interface — they shield the magnetic field and cause measurement errors. If using a steel piston, ensure the piston bore containing the magnet is at least 3 mm non-ferrous material thickness (brass, aluminum sleeve, or plastic insert) around the magnet.
What is the accuracy of a magnetostrictive sensor in a hydraulic cylinder application?
Standalone sensor accuracy (linearity): ±0.05 mm. In a hydraulic cylinder system, total position accuracy depends on: sensor linearity (±0.05 mm) + cylinder seal hysteresis (0.01–0.05 mm) + mounting tolerance (install the magnet within ±0.5 mm axially, not critical). Thermal drift: temperature coefficient of offset <0.002% FS/°C. At 60°C hydraulic oil temperature (normal operating), drift on 1000 mm stroke is <0.4 mm. For precision motion control applications requiring <0.1 mm repeatability in a hydraulic axis, magnetostrictive sensors meet the requirement comfortably.
Is the sensor compatible with servo hydraulics and position control loops?
Yes. SEGMENsensor magnetostrictive sensors are used in closed-loop hydraulic position control with update rates up to 1 kHz (4-20mA) or 100 kHz (SSI). For servo hydraulic axes, SSI interface is recommended — lower latency than analog, immune to noise from proportional valve solenoids. Compatible with servo controllers that accept SSI absolute encoder feedback (most servo drives support SSI). For CANopen DS406 profile (common in mobile hydraulics with CAN bus), specify the CANopen variant. Consult SEGMENsensor for controller compatibility documentation.
What is the MOQ and lead time for hydraulic cylinder magnetostrictive sensors?
MOQ 10 pcs for standard configurations (stroke 100–2000 mm, SSI or 4-20mA output). Samples 1–2 pcs accepted. Standard lead time: 3–5 weeks. Custom stroke length (specify in 1 mm increments), non-standard outputs (Profibus, EtherCAT), stainless steel head, special magnet bore: add 2 weeks. Full OEM (private label, custom connector): MOQ 50 pcs, 6–8 weeks. CE, RoHS documentation with every shipment. Factory: Segmen Industrial Development Co., Ltd., Registration No. 91440300MAEUXXQU04, Shenzhen, Guangdong, China.
Ready to Source Hydraulic Cylinder Magnetostrictive Position Sensors from China OEM Factory?
Tell us your stroke, pressure rating, output interface, and cylinder bore — we'll configure the correct sensor and send a quote within 24 hours.
