When Jochen Dorlöchter, Executive Manager of Walther Wolf, talks about the company’s achievements over the last years, one can’t help but recognise the pride in his voice. In recent years, many things have changed in the production halls of Wendelstein near Nuremberg, Germany. For the installation of an automated machining centre, Dorlöchter even had to pull down a wall. Less visible but still evident are the effects of consequently working towards an automated production. A number of changes have led to significant time savings and an increase in turnover.
Dorloechter’s great-grandfather founded Walther Wolf in 1907. At that time, it still was an engraving plant. Later, they started to work in mould making and today specialise in plastic injection moulding. The current staff of 55 employees works mainly on moulds for technical components. Among Walther Wolf’s customers are big players such as Siemens, INA, ZF Friedrichshafen and Bosch.
Jochen Dorlöchter is someone who always seems to think about how to optimise processes and the quality of his products. This is one of the reasons why Walther Wolf has its own department for measuring. Five workers are engaged in the specially established measuring room, working with tactical and optical methods to ensure that Walther Wolf’s customers only receive high-quality products. Dorlöchter is proud to be able to verify the accuracy of his products himself.
One of his largest projects started in 2008. In co-operation with EDM specialist Zimmer & Kreim, he converted his section for the processing of graphite electrodes to a complex and fully automated machining centre. This centre is able to erode, measure, mill, engrave with a laser and clean the electrodes simultaneously, therefore combining a huge number of processes into one single unit. Since its implementation, the cell enabled Walther Wolf to drastically reduce idle times: With the help of a software that manages different jobs, the automated processes are carried out simultaneously and 24 hours a day.
According to Dorlöchter, the decision of working with Zimmer & Kreim was an easy one. “Their software is very user-friendly,” he explains, “and it runs very reliably.” Another advantage of Zimmer & Kreim’s software is its flexibility. Users do not depend on particular machines but are free to decide whose products they use in their production. Because of its interface function, Dorlöchter is also able to implement further advanced features in the software.
The 23-metre-long machining centre in Walther Wolf’s halls consists of Laser stations by Acsys, a measuring station by Zeiss, RXP machines by Röders and cleaning stations and EDM systems by Zimmer & Kreim. All these different stations, completed by several metres of storage cupboards, are served by a tower unit with a gripper that is moved electronically. In this automated cell there is room for about 1,000 electrodes at the same time.
All jobs executed by the individual stations are managed with the software by Zimmer & Kreim. This software is one of the significant advantages of the automated cell. The job manager handles offset data, co-ordinates the different processes and collects data around the stored and machined electrodes.
Dorlöchter is particularly happy about the usability of the software. According to him, Zimmer & Kreim’s updates are also a great help. Due to them, the machining cell works faster and more efficient today than it did when he first installed it. Additionally, the software has an interface function that allows operators and users to implement their own programs. Moreover, Dorlöchter is very glad about the support of Zimmer & Kreim. “If there were problems, they were settled very quickly and efficiently in co-operation with Zimmer & Kreim,” he says.
The open structure of Zimmer & Kreim allows Dorlöchter and his company to implement processes or optimisation measures that are not available in the market. For the company’s manager, this is an incomparable advantage, as every company has its own needs and its own optimisation potential. It is Dorlöchter’s goal to take full advantage of the interface. In the past years, he was able to realise several projects that were only possible because it is so easy to combine one’s own innovations with Zimmer & Kreim’s job manager.
One thing that has changed since the new cell was implemented is that many tasks that had to be monitored before can now be carried out at night. Things that take up a lot of time therefore do not demand precious working hours. The measuring unit, for example, primarily works at night time without the necessity for an operator being present.
For further improvements, Dorlöchter had several cameras installed. One camera is attached to the tower unit and another camera to the measuring station. That way, the manager or any other operator can check whether everything is running according to plan.
The night-time operation is only one of the results of Dorlöchter’s automation project. All in all, the changes have lead to working more time-efficiently. Staff working time was tremendously reduced to two and a half minutes per electrode. Before implementation, the same work took up more than eleven minutes of working time. All together, there was a strong decrease in the resting time of every electrode. For the company, this means that the machines are working with a higher workload.
“Vacancy can’t happen,” says Dorlöchter. Automation for him led to an increase in not only occupancy but consequently to better planning predictability. One reason is that the job-manager software monitors all electrodes, which prevents breaks in processing. At the same time, this monitoring provides detailed projections about machining times. This allows the company to plan ahead and therefore prevent vacancies.
Walther Wolf is a company that always tries to go further. Dorlöchter is particularly proud of certain added features that are—as he says it—“not available in the free market”. One of these projects is an automatic correction function which he was able to implement in the existing software. As Dorlöchter explains, the advantage of this correction is that it had to be programmed only once. This feature is able to make modifications on the calculated sparkgap. The necessity to control the electrode individually and to adjust the machining process is therefore gone.
But Walther Wolf’s innovative spirit did not stop there. One part of the process of machining electrodes had been particularly time and cost-consuming in the past: Whenever a new electrode was needed, first of all, a graphite blank had to be ordered to size. What’s more, the graphite needed to have varying dimensions for different applications.
The part that took up most of the time in this process was the incorporation of every single graphite bar. Once it was ordered, the graphite needed to be installed into the system including its measurements. Once the electrode had been used, it had to be removed again. So the company came up with a new way of dealing with this process. Dorlöchter started to order graphite bars that were three times the size of what was needed. According to calculations, this was the largest size that was still machinable in every one of the many units of the process. The longer graphite bar is installed in the same way as it had been in the case before.
The huge difference is that the graphite can now be used an average of three times. After it has been used for the first time, the electrode is not removed from the system but stored in one of the cupboards. There it sits and waits until an electrode is needed that fits to the dimensions of the remaining graphite bar. Thanks to the aid of the software that stores all important information about the graphite bars, this is an automated process without the need to monitor the bars. Each electrode additionally can keep its original registration in the system. The software is capable of identifying the electrode that best fits the requirements for the next project.
According to Dorlöchter, the same graphite bar can be reused three times. Additionally, the set-up time of each electrode has been reduced. Before, it took roughly ten minutes per electrode to install it in the system. This time was cut in half because it is not necessary to install the graphite part over and over again. Instead, it can remain in the system.
When Dorlöchter is asked whether he will ever complete his project of automation, he just smiles and remains silent. Then he points to the end of the machining centre and explains: “Well, it is obvious that we ran out of space for extending the length of this automated cell a while ago. To have enough space for installing it on around 23 metres we even had to tear down a wall and now there is no room for an expansion here. But I can promise that I haven’t run out of ideas yet.”