Solenoid Force Calculator
The Solenoid Force Calculator computes electromagnetic pull force using Maxwell stress tensor (F = B²A/2µ₀) for solenoid actuators and electromagnets. Features interactive force-vs-gap SVG chart, coil design parameters, core material selection (soft iron, silicon steel, ferrite), saturation detection, and thermal rating. Free, no signup required.
Presets
Core Material
Coil Parameters
Results
Force vs. Air Gap
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What is a Solenoid Force Calculator?
A solenoid force calculator computes the electromagnetic pull force of solenoid actuators and electromagnets using the Maxwell stress tensor equation: F = B²A/(2µ₀), where B is the flux density in the air gap and A is the core cross-section area. The calculator accounts for core material permeability, magnetic circuit reluctance, and saturation effects. The interactive force-vs-gap chart shows how force varies non-linearly with air gap distance — a critical design parameter for relays, valves, locks, and actuators.
How to Use This Calculator
- Enter coil parameters: number of turns, current, coil dimensions
- Select a core material (soft iron, silicon steel, ferrite) or choose a preset application
- Set the air gap distance to calculate the pull force at that gap
- View the force-vs-gap curve to understand how force varies with stroke
- Check for saturation and thermal warnings to ensure safe operating conditions
Frequently Asked Questions
How is solenoid pull force calculated?
Solenoid pull force is calculated using the Maxwell stress tensor: F = B²A/(2µ₀). First, compute the MMF (N×I), then the total reluctance of the magnetic circuit (core + air gap). The flux Φ = MMF/R gives the flux density B = Φ/A. Force depends on B² so it increases dramatically as the air gap closes.
Why does solenoid force increase as the air gap decreases?
The air gap has much higher reluctance than the core (µr ≈ 1 vs 5000). As the gap closes, total reluctance drops rapidly, increasing flux density. Since force depends on B², it follows an approximate 1/gap² relationship, creating the characteristic non-linear force-stroke curve.
What is magnetic saturation and how does it affect force?
Magnetic saturation occurs when the core material reaches its maximum flux density (e.g., 1.5 T for soft iron, 2.0 T for silicon steel). Beyond saturation, increasing current produces diminishing returns in flux and force. This calculator detects saturation and warns when B exceeds the material's limit.