Premiere: Pulse Process

 

First PECM machine at Leistritz

 

The Leistritz turbine technology at the Nuremberg location underlines its pioneering role in the market: With the new PECM system (pulsating electrochemical metal processing) it is possible for the first time to produce flow contours on engine blades in a combined, that means continuous and pulsating, ECM process.

Increased presicion and automatic parts supply

This machine operates with increased precision  as  well  as  automatic  parts  supply.  The project was developed in response to a customer order for high-pressure compressor blades used in the Airbus A320 engine. Since there was no such production concept on the market, it was implemented for the first time. Adaptation work was carried out on the conventional base system. The process engineers from the turbine technology business unit and their colleagues from the production technology business unit in Pleystein worked together on it. It was a combined competence of mechanical engineering and ECM process technology.

Increasing the accuracy of reproduction, reducing the set-up effort

As a result of the development in the field of high pressure compressors and complex 3D geometries  with leading and trailing edge shapes with close  tolerances,  it was  necessary to reduce the gap width between the workpiece (the anode) and the tool (the cathode) during ECM. A reduced gap width increases the accuracy of reproduction and reduces the set-up time. On the other hand, a reduced gap between the tool and the workpiece is, however, detrimental to the removal of waste products from the process. Therefore the current is switched off with a specific frequency (normally   10 Hz) and the cathodes moved away from the workpiece so that the gap can be flushed out. Thus, the actual machining process is interrupted. Compared with generator countersinking with its constant gap and constant electrical supply, these interruptions bring an increase of machining time.

Utilizing the advantages of two processes

It was therefore necessary to build a machine of our own design which combines both processes and therefore also benefits from the advantages of both processes. The redesign facilitatds the usage of what was called the ‘pulse process’ alongside the well-established generator ECM process Leistritz have had. In addition, four-sided machining was introduced for the first time which reduced the ‘countersink flash’ of the original process to a minimum with the result that absolutely no or perhaps only minor manual processing is necessary. A further important point was that for the first time the machine was constructed with an independent electrolyte supply and could therefore be operated directly in the manufacturing areas. In addition, thanks to intelligent automation, it is possible to leave the machine working unattended throughout a shift.

Expanding the protfolio

The construction of this machine has opened up completely new possibilities: components from the high-pressure compressor sector requiring highest precision as well as very small components can now be manufactured. These are for example parts manufactured by metal powder injection molding or 3D printing and requiring only surface finishing. As a result of the decentralized supply, it is now also possible to bring mechanical machining centers and ECM machining together in the production facilities and to automate the engine blades manufacturing process.

We are currently the only company to have a PECM system in operation.

Harald Brand, Plant Manager at Leistritz Turbinentechnik GmbH Nürnberg

We have developed a production machine that combines all the advantages of the ECM and pulsating processes. We are therefore more precise, faster and more versatile in our application.

Georg Schmidt, Head of Work Planning at Leistritz Turbinentechnik Nürnberg GmbH