The core technology – shock wave- or
electrohydraulic fragmentation

The shock wave or elec­tro­hy­draulic frag­men­ta­tion process is cur­rent­ly only used to a lim­it­ed extent in Ger­many. It can be clas­si­fied in the field of pulsed pow­er tech­nol­o­gy, which rep­re­sents a large­ly new tech­nol­o­gy in Ger­many. Pre­vi­ous appli­ca­tions at research insti­tutes were most­ly lim­it­ed to the homo­ge­neous frag­men­ta­tion of old con­crete. Com­mer­cial appli­ca­tions exist in the form of extra­cor­po­re­al shock wave ther­a­py (“lithotrip­sy”), sheet met­al form­ing or sand­ing of sand cast­ings in the cast­ing industry.

The mate­r­i­al-selec­tive elec­tro­hy­draulic frag­men­ta­tion process (EHF) from Impul­sTec GmbH offers a con­vinc­ing solu­tion for the mate­r­i­al sep­a­ra­tion of com­plex mate­r­i­al com­pos­ites. The method uses mechan­i­cal shock waves, which are gen­er­at­ed in a flu­id medi­um, in order to bring about an ener­gy cou­pling and thus a sep­a­ra­tion of the composites.

The shock waves are gen­er­at­ed with the help of the elec­tro-hydraulic effect, in which a short-term, intense arc is ignit­ed in a liq­uid between two elec­trodes. To this end, pulse capac­i­tors are charged to a work­ing volt­age of up to 50 kV and then con­nect­ed to the elec­trode sys­tem of a frag­men­ta­tion ves­sel filled with a flu­id medi­um with the aid of a spark gap.

The so-called shock dis­charge that is formed between two elec­trodes cre­ates a rapid­ly expand­ing plas­ma chan­nel, which caus­es shock waves to prop­a­gate radi­al­ly in the flu­id. Pres­sures of sev­er­al thou­sand atmos­pheres occur near the place of ori­gin. Dur­ing the prop­a­ga­tion in the ves­sel, these shock waves hit the mate­r­i­al immersed in the flu­id and caus­ing it to break up .

As a result, there is no con­tact with a sol­id grind­ing tool, result­ing in an essen­tial­ly con­tact-free sep­a­ra­tion process. Due to its high mate­r­i­al selec­tiv­i­ty, the shock wave process from Impul­sTec GmbH caus­es break up at the inter­faces of dif­fer­ent mate­ri­als and is there­fore pre­des­tined for use on com­plex indus­tri­al mate­ri­als and com­pos­ite materials.

Scheme of a discharge circuit

The fragmentation effect is achieved through the effective separation mechanisms:

The homo­ge­neous ener­gy input caus­es increased frac­ture selec­tiv­i­ty on dif­fer­ences of mechan­i­cal strength
Pres­sure increas­es at inter­faces of mate­ri­als with dif­fer­ent acoustic properties
Elec­tri­cal selec­tiv­i­ty leads to increased ener­gy input in the area of con­duc­tive com­po­nents in the composite

Beneftis of shock wave technology:

con­tact-free and there­fore low-con­t­a­m­i­na­tion frag­men­ta­tion process
no fine dust due to work­ing with an process fluid
high lev­el of automa­tion enable oper­a­tion with­out addi­tion­al qualifications
easy adap­ta­tion to cus­tomer-spe­cif­ic applications
easy main­te­nance and a wide range of services
robust, scal­able tech­nol­o­gy for use in an indus­tri­al envi­ron­ment due to oper­at­ing volt­ages up to 50kV