Automating the mold insert process

Part of Rausch Formenbau’s focus on process improvement last year was to more closely examine its electrode manufacturing process. While the company had long been employing sinker EDM as a manufacturing method, it had been using this technology only when the geometry or required surface structure did not allow any alternatives. Because the existing eroding machine had only a small magazine with 16 positions, it could not run for a long period without operator intervention. As much as possible was therefore milled directly. However, the filigree roughing of narrow cavities was not a sufficiently reliable process. "If tool wear isn’t detected early, the tool will break. So those milling tasks can’t be processed without supervision,” explains Rausch, who also heads the CAD/CAM department. In contrast, the processing of small webs as electrodes in graphite is very reliable. And milling is very fast, making the time requirement for eroding tolerable. The company therefore decided to significantly improve its electrode manufacturing by implementing three measures:

• Increasing capacity with two new Genius 1200 and 700 EDM machines from Zimmer & Kreim.
• Networking the milling and eroding machines, enabling unsupervised 24-hour operation by implementing the Zimmer & Kreim Chameleon handling system for managing and storing 32 milling tools, 135 electrodes and 9 workpieces on pallets.
• Establishing an automated and reliable CAD/CAM process able to keep up with the high output of the sinker EDM machines. To do this, the existing Tebis installation was expanded.

As soon as all data and manufacturing steps are defined for the electrodes for a given part, they can be transferred to the control system. XML files are used as the transfer medium, as Tebis generates these by default for every electrode project. These data are imported into the software of the handling system and entered in the job list for the manufacturing cell. Machining can start as soon as the magazine is loaded with the required blanks. The holder with the part is positioned in the milling machine and the calculated NC programs are called up. Once the electrode has been milled, it is returned to the magazine until required by the EDM machine. Tebis provides not only the approach coordinates and direction but also all other data on the electrode and the eroding process (quality, material, arc gap, machining type, burn depth, etc.). The required commands for the eroding machines can be generated from these data. Once the XML data are imported and the magazine is loaded, no further operator intervention is required until the part is completely eroded.