INDUSTRY COMPONENT

Movable Core

Movable core is the moving ferromagnetic element in LVDT sensors that converts linear displacement into electrical signals for precision measurement.

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Component Specifications

Definition
The movable core is a precisely manufactured ferromagnetic component that slides axially within the primary and secondary coils of a Linear Variable Differential Transformer (LVDT). Its position relative to the coils creates differential voltage outputs proportional to displacement, enabling accurate linear position measurement with high resolution and repeatability in industrial feedback systems.
Working Principle
The movable core moves linearly within the LVDT's electromagnetic field. As it displaces, it changes the magnetic coupling between the primary excitation coil and two secondary coils, creating differential AC voltage outputs. The phase and amplitude of these voltages indicate both direction and magnitude of displacement, with null position occurring when the core is centered between secondary coils.
Materials
High-permeability nickel-iron alloys (typically 80% Ni, 20% Fe), laminated silicon steel, or ferrite materials with low coercivity and high magnetic saturation to minimize hysteresis and eddy current losses.
Technical Parameters
  • Linearity ±0.1% to ±0.5% of full scale
  • Resolution Theoretically infinite (limited by electronics)
  • Null Voltage <0.5% of full scale output
  • Core Diameter 3-25 mm
  • Stroke Length ±0.5 to ±500 mm
  • Frequency Response 50 Hz to 20 kHz
  • Operating Temperature -55°C to +150°C
Standards
ISO 16063-21, DIN 43760, IEC 60668

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Movable Core.

LVDT movable core linear variable differential transformer core displacement sensor component ferromagnetic core position measurement feedback sensor part industrial sensor component Movable Core Movable Core in Machinery and Equipment Manufacturing

Parent Products

This component is used in the following industrial products

Feedback Sensor (e.g., LVDT)

A sensor that provides real-time position feedback for servo control valve spools.

View Product Details

Feedback Device (e.g., LVDT)

A sensor component in servo valves that provides real-time position feedback of the valve spool to the control system.

View Product Details

Engineering Analysis

Risks & Mitigation
  • Magnetic saturation at extreme positions
  • Mechanical wear from continuous sliding
  • Temperature-induced dimensional changes
  • Contamination affecting smooth movement
  • Demagnetization from shock or excessive heat
FMEA Triads
Trigger: Abrasive particles in operating environment
Failure: Increased friction and wear, leading to position measurement errors and reduced lifespan
Mitigation: Implement protective bellows or seals, use filtered air systems, select hardened core materials, establish regular maintenance schedules
Trigger: Excessive operating temperature beyond specifications
Failure: Material expansion/contraction altering magnetic properties and dimensional tolerances, causing measurement drift
Mitigation: Install temperature sensors with compensation circuits, ensure proper cooling, select materials with low thermal expansion coefficients
Trigger: Mechanical misalignment during installation
Failure: Binding or uneven movement, creating nonlinear output and premature wear
Mitigation: Use precision alignment fixtures during installation, implement run-in procedures, verify perpendicularity with laser alignment tools

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Diameter tolerance: ±0.005 mm, Straightness: <0.01 mm/100 mm, Surface finish: Ra 0.4 μm max
Test Method
Magnetic permeability testing per ASTM A342, dimensional verification with coordinate measuring machines (CMM), linearity testing with laser interferometers, thermal cycling per MIL-STD-810

Procurement Evaluation Criteria

Not customer reviews or live demand data. These dimensions support RFQ preparation and supplier evaluation.

Technical documentation
4/5
Manufacturing capability
4/5
Inspection readiness
5/5
Supplier transparency
3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

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Frequently Asked Questions

What is the main function of the movable core in an LVDT?

The movable core converts mechanical linear displacement into proportional electrical signals by altering magnetic coupling between primary and secondary coils, enabling precise position measurement.

Why are nickel-iron alloys preferred for movable cores?

Nickel-iron alloys (80/20) provide high magnetic permeability, low coercivity, and minimal hysteresis losses, ensuring accurate signal generation with excellent temperature stability and linearity.

Can movable cores be replaced independently in LVDT sensors?

Typically no - movable cores are precision-matched to specific LVDT assemblies during manufacturing. Replacement requires complete sensor recalibration due to critical magnetic and mechanical tolerances.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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