In Germany, the shock wave or electro-hydraulic fragmentation is currently only being used to a limited extent. It should be regarded as a type of pulsed power technology, which represents a largely new technology in Germany. Previous applications at research institutes were limited mostly to the homogeneous fragmentation of old concrete. Commercial applications exist in the form of extracorporeal shock wave therapy ("lithotripsy"), sheet metal forming or sand removal from sand mold parts in the casting industry.
Selective electrohydraulic fragmentation process (EHF) of ImpulsTec
The material-selective electrohydraulic fragmentation process developed by ImpulsTec GmbH uses mechanical shock waves generated within a fluid medium to fragment materials. The shock waves are generated using an electrohydraulic mechanism to ignite a brief, intensive electric arc between two electrodes.
This is achieved by charging pulse capacitors up to a working voltage of up to 50 kV and then discharging them across the spark gap of an electrode system in a fragmentation vessel filled with a shock wave propagation fluid, especially water.
The resulting brief, intense arc forming between the two electrodes generates a rapidly expanding plasma channel, which creates radially propagating shock waves in the fluid. This creates pressures of several thousand atmospheres near the origin. As these shock waves propagate through the vessel, they hit the materials immersed in the fluid, causing it to break up. This avoids contact with the solid materials, resulting in an essentially contact-free separation process.
The high material selectivity of the industrial shock wave process developed by ImpulsTec GmbH causes break up at the interfaces between different materials, which makes it ideal for complex industrial materials and composites.