The topic of automation is diverse, ranging from zero-point clamping systems on milling centers with pallet changers to linked, fully automated manufacturing cells. Multiple clamping is the most basic type of automation. In a next step, for example, parts can be provided on a pallet in front of the machine, and the pallets can be changed either manually or automatically. The final step could be to link multiple machines through a handling system or robots.

The company started with its EDM department, which was the ideal place to launch the first automation project in his mold shop.

We started our first automation efforts in our EDM department, Because electrode milling and EDM are time-consuming processes, they ideally are suited for automation. The implementation is relatively straightforward. It is a good opportunity to learn when you are just beginning with automation, because if something goes wrong at the beginning, throwing away an electrode is not a big deal. But, with a finished workpiece, it would not be that simple. Of course, you need to control the entire process and to do so, you should never start with the most complicated process. Today, we are milling around 25,000 electrodes per year—even the Chinese cannot work any more efficiently!

To control the process, please try to work with transponder chips based on RFID in its automated EDM line that CERTA makes. CERTA is a medium-sized software and process consulting company and a 100 percent subsidiary of Erowa Group in Büron, Switzerland. The system assigns electrodes to workpiece holders and makes them available in the CERTA central process control system, preventing errors during the insertion of the parts into the machine. When machinists insert the workpiece (or in this case, electrode) into a magazine, the system immediately recognizes it in the corresponding magazine position. The system also provides the data centrally. Machinists therefore can change workpieces correctly and flexibly.

NC programs for processing, offset data for tools, tool positions in magazines as well as pallet and loading information are provided centrally in the CERTA process control system based on the order. All of the required information is on the chip. We insert the tools via barcode, and the system does the rest automatically. Thus, clamping errors and the like are practically eliminated. But of course the whole process has to be simulated before going into production.

The process for determining the offset data of the electrodes is fully automated at the presetting station. The necessary geometry data, dimensions and tolerances are automatically transferred from all popular CAD systems to the measuring machine. The required measuring points are defined in the CAD plug-in. If deviations occur in the target or actual comparison during the measuring process, the required process steps are automatically initiated. This may involve remanufacturing or reworking, for example.

After successfully automating its EDM department, the company also largely automated its milling lines. then runs two fully automated lines, a smaller line with two Hermle C50U units and a robot and a larger line with four Hermle C42U machines, a washing and measuring station, 60 pallets and space for 400 tools. According to Hofmann, the latter is as efficient as 10 stand-alone machines. Even though automation makes up half the investment, it is still worth it.

Even though automation makes up half the investment, it is still worth it.

Automating the milling lines was not the easiest task,  because fully automated milling of hardened mold inserts involves much more tool wear and requires even higher accuracy than EDM die-sinking and electrode milling. As a result, the process has to be highly standardized and needs more than machines, pallets and robots.