03.09.2019

URMA EXPERIENCE - Erowa AG

Zeropoint clamping systems from EROWA are world-famous and popular. Their complex production is time-consuming. Guido Schwarzentruber, responsible for tool purchasing, relies on high-quality reaming tools like URMA RX. This enables him to automate many production steps during the night.

"In the evening, when our employees go home, the robots take over," says Guido Schwarzentruber. They take the housings to be processed out of the Kardex system, feed them to the machine, start the program and run it automatically. Around 40 work steps are performed fully automatically. The machines run all night. In the morning, the processed workpieces are neatly lined up. "For this to work, a lot has to fit together. Schwarzentruber knows what he is talking about. He has been working for EROWA for 35 years. He has experienced the most diverse upheavals and further developments. "When I started, automation wasn't a big issue", he remembers. "Today it is an important branch of EROWA's business." So it is only logical that EROWA should also automate the production of its proven zero point clamping systems wherever possible.

Reliable tools are the be-all and end-all

In any case, you must be able to rely on the tool. Until a few years ago, the machining of precision bores in particular was quite a challenge in this respect. Schwarzentruber remembers: "When pre-machining with boring tools, we were not able to reliably maintain the diameter. This also had an effect on the subsequent roller burnishing, as we were unable to achieve the required surface quality". Yet this particular work step should have been automated overnight. "Instead, we had to load each component into the machine again during the day and unscrew and burnish the holes. This was not satisfactory for us. A solution to the situation was not in sight until URMA salesman Kim Arnold encouraged him to try something completely different: Reaming with the URMA RX Reaming. The URMA RX Reaming interchangeable boring head system is known in the industry for its high quality, precision, and user-friendliness.

With trials to success

But a little patience was also required here: "In 2014, we started the first reaming tests. The first tests revealed the following problems: long chips (not optimal for unmanned production), too high torque (machine standstill), not maintaining the required surface (required Ra0.8 - Rz max 3). Long chips were produced without end", smiles Schwarzentruber. As an experienced metalworker, he knows of course that it takes a few trials before the necessary experience with a new tool is available. For the second test, the gate geometry was adapted and a chip former was ground onto the reaming insert. This change resulted in controlled chip evacuation, a reduction in torque absorption and a suitable surface. In addition, the process had now become 20 times faster with the change to reaming. For example, a feed speed of over 1000mm/min could be achieved for the material 1.2312 / 40CrMnNiMo8-6-4).
However, it still took some time until the production process was released. The surface of the bore has a requirement of Ra 0.8 / Rz max 3, which was more than fulfilled with Ra 0.11 / Rz max 0.9. However, the surface showed the typical visible shading caused by the high feed rate. This had to be approved by various clarifications.

Automated drilling with URMA Reaming RX

However, for the last 3 - 3.5 years it has been running very well. The URMA tools meet the high demands on process reliability, diameter accuracy, and surface quality in the best possible way. URMA RX reaming inserts can very well be used at night. So we manufacture a wide range of diameters (ø50 - 108mm) in eight different housing types. It does not matter which one is in the machine; it works flawlessly. "In this way, at least three different housings are processed each night," says Schwarzentruber with great satisfaction. Otherwise there is not much more to add. "It's going so well that we don't have to worry about anything when it comes to reaming."

Productivity significantly increased

After switching to reaming, the production volume has increased massively. "In the beginning we made lot sizes of 20, today there are many more." However, the decisive factor for the change to reaming was not the processing time, but the process reliability. This remains constant even when changing the reaming inserts, because the high-precision RX interface with a guaranteed change accuracy of less than 4 micrometers eliminates the need for readjustment of the tool. "Take out the old reaming insert, clean the interface, put in the new reaming insert, and off you go. Simply great," nods René Portmann, head of the Machining Production Unit. He also greatly appreciates the support provided by tool supplier URMA. "We worked very closely together for the tests. We were well supported with every problem, even during prototype production," he confirms.

Loading robots optimize production

In addition to all kinds of clamping systems, EROWA has also been known for its loading robots since 1987. The various automation solutions cover every need and are available in many different sizes. For small footprints EROWA has developed a robot that takes up only two square meters of space. "A bestseller", as Michael Gautschi, Marketing, confirms. "After all, if you want to be competitive and have high productivity today, there's no getting around automation," he knows.
Of course, EROWA robots are also used in his own company. The EROWA Robot Dynamic Linear is used for housing processing, for example. "This is a so-called manufacturing cell," says Portmann. "Automation has changed a lot. Today, the employee is no longer just an operator but a production manager. He prepares everything necessary for the program start, such as loading the trays, assigning the corresponding programs and starting the process.

Control system monitors the tools

In addition to handling the up to 40 programmed work steps, the control system also monitors the tools. "For each existing tool an expected tool life in minutes is defined. If this is used up, the control system displays this graphically and the CNC machine automatically inserts a sister tool," explains Schwarzentruber.
Operator and programmer Markus Suter is particularly pleasantly surprised by the long tool life of the URMA RX reaming inserts. In plain language: "I have now been working on this production cell for two years and have never had to change the URMA inserts". Apart from the high product quality of the URMA RX reamers, this is of course also a result of the careful handling of machine and material.

New challenges for the tools

Soon URMA salesmen Kim Arnold, Guido Schwarzentruber and René Portmann will be reunited. Because the next challenges are already ahead. "A new design is pending for the clamping systems," says Schwarzentruber. In addition to an adjustment of the form and also a change of material to a different alloy, this means an adjustment of all metalworking processes. Once again, the know-how of URMA and EROWA will be required until the correct cutting angles and feed rates lead to optimum machining. Portmann will receive active support from URMA salesman Kim Arnold. Together they will thoroughly analyze the new requirements and then use a customized tool. Together with a reliable partner, this next hurdle is also a new task in a Spanish environment.

The URMA RX reaming system:

The URMA RX reaming system small and medium cover bores in the range of diameter 7,600 to 140,600mm. The quick-change system is particularly user-friendly and offers the highest repeatability for each insert change. The Swiss tool specialist URMA is known worldwide for its innovative solutions in precision boring. These are primarily in demand from companies in the automotive and aircraft industries, manufacturers of hydraulic components and pumps, as well as companies in general mechanical engineering.