ELECTROMAGNETIC PULSE FORMING PREPRESS

Electromagnetic Pulse Forming (EMPF) Coil & Tooling Vector Prepress Guide

Electromagnetic Pulse Forming (EMPF) and Electrohydraulic Forming (EHF) use rapid discharges of stored electrical energy to accelerate sheet metal into die cavities at velocities exceeding $100–300\text{ m/s}$, doubling formability and eliminating springback.

1. Lorentz Force Dynamics & Hyperplastic Strain Rates

When high-frequency pulse current passes through an actuator coil, transient eddy currents in the sheet metal generate opposing magnetic fields. The resulting Lorentz repulsion drives the sheet into an open die cavity at high strain rates ($\dot{\varepsilon} > 10^3\,\text{s}^{-1}$), suppressing necking instabilities.

2. Engineering Specifications & Tolerances

3. EMPF Actuator Coil & Die Evacuation Vector DXF Rules

• Archimedean Coil Spiral Clearance: Driver coil vector cutpaths must maintain $1.0\text{mm} \pm 0.05\text{mm}$ inter-turn insulation gap filled with dielectric epoxy (dielectric strength $> 20\, ext{kV/mm}$).
• Vacuum Die Evacuation Ports: High-velocity forming traps air pockets; die DXFs must incorporate distributed $arnothing 0.8 ext{mm}$ vacuum relief vent holes.
• Non-Magnetic Die Inserts: High-wear die inserts exposed to magnetic flux must be CNC machined from non-magnetic beryllium copper or non-conductive ceramics.