Emerging from the process – development partnership between machine manufacturer and tool manufacturer

“We have a unique approach when we receive customer inquiries,” says Meinolf Wolke, Sales Team Leader at ELHA-MASCHINENBAU Liemke KG (ELHA) in Hövelhof. The medium-sized, owner-managed special machine construction company places the workpiece and its machining at the centre of development and devises an optimal solution perfectly designed for the process sequence. “In doing so, we take all the technical and economic requirements into account,” clarifies Wolke further. Only then do those responsible decide whether an existing machining concept can be used for the process or whether an individual, application-specific construction is required. Meinolf Wolke explains: “As well as providing the machine, we offer services that stretch from process development and the construction of fixtures all the way through to complete, ready-to-operate solutions with automation and production support.”

“The machining tasks are often as unique as the parts themselves – including in terms of the workpiece materials,” adds Alexander Wiesner, Technical Advisor at MAPAL. “Of course, a lot of machining work on complex parts can be achieved with standard tools. But that often comes with significant drawbacks in terms of cycle times, quality, and cost-effectiveness, particularly when large quantities are being produced.” In these cases, special tools that are precisely calibrated by MAPAL for the machining task in question are preferred.

“During the tool design phase, it’s essential to determine the necessary parameters for the machining process,” says Wiesner, “particularly in the case of challenging geometries.” In order to design the process in the best possible way, MAPAL often makes prototype tools. These are then used to carry out extensive tests with the part to be machined. “That, in turn, helps the equipment manufacturers design the machine with the values identified during testing,” continues Wiesner. He says that MAPAL has had a long-standing partnership with ELHA in this area. The following three examples demonstrate the resulting benefits to customers:

“We were dissatisfied with the solution that we had been using for drilling from solid in aluminium when machining a suspension arm, which included creating a fitting,” remembers ELHA Project Leader Friedhelm Dresmann. At the time, the company was using tools with brazed PCD cutting edges. In order to keep the machining time as low as possible, these drills were being used with very high feed rates. The disadvantages of this solution were the high drive power required and the insufficient durability of the PCD cutting edges on the solid drill step. In search of a solution, those responsible at ELHA turned to MAPAL. Together, the employees of the machine manufacturer and the tool manufacturer worked to find a solution. What they came up with was a hybrid tool. The tip of the tool is equipped with three-bladed, CVD-diamond coated, ISO-indexable inserts for drilling from solid. The fitting is created using brazed PCD cutting edges on the second step of the tool.

MAPAL’s research engineers tested the new tool in their own R&D centre. The results were impressive. In addition to the lower costs of the indexable inserts overall, the positive blade geometry meant that less drive power was required. What’s more, the previous solution had often produced long metal chips – with the new tool, this was no longer an issue. The indexable inserts at the tip of the drill, which are under significant stress, can be quickly and easily flipped or replaced. As a result, the maintenance costs were also noticeably reduced. Altogether, the suspension arm manufacturers’ production costs for each drilled bore were reduced by over 50 percent.

“We also worked with MAPAL to find an efficient solution for machining forged suspension arms,” explains ELHA Project Leader Marcel Thieschneider. “Our goal was to develop process-reliable tools while maintaining the required cycle times.” For the suspension arm, a yoke needed to be created from the solid material at the end of the arm. During the required four-spindle machining process, the long-chipping workpiece material demands very high drive power to the machine. In addition to this, the internal contour of the part features a number of angles and radii, making the expulsion of chips during milling difficult.

“In order to ensure short process times, we developed a disc milling cutter with ISO indexable inserts that enables roughing and finishing with minimum quantity lubrication in just one step,” recalls Alexander Wiesner. The indexable inserts are coated with CVD diamond. The precisely defined arrangement of the individual inserts limits the drive power required. After considering the comprehensive tests at MAPAL and the data that resulted from them, ELHA set its machine to operate at this drive power. A positive side effect of using the disc milling cutter was the reduction in cycle time, as only one cut is needed. On top of that, the tool only occupies one row of spindles, reducing the resulting tool costs for the end customer.

„Unser Kunde stellt Verteiler für die Hochdruck-Kraftstoffversorgung von Ottomotoren her. Dafür werden tiefe Bohrungen in schlanke geschmiedete Edelstahl-Rohlinge eingebracht“, sagt ELHA-Projektleiter Jörg Rodehutskors. Das Material ist schwer zerspanbar. Die Bohrung ist 300 mm tief. Der axiale Verlauf des Bohrers muss möglichst gering sein. Ansonsten würde die geforderte Mindestwanddicke des hoch druckbelasteten Bauteils unterschritten. Früher bearbeitete der Hersteller diese Bohrungen in einer separaten, einspindligen Werkzeugmaschine mit einem Einlippen-Tieflochbohrer. 

Um seine Prozesse zu optimieren, stellte der Kunde die Anforderung an ELHA, dass die beschriebene sowie alle anderen Bearbeitungsaufgaben mehrspindlig innerhalb ein- und desselben Fertigungsmoduls ausgeführt werden. Die Teile sollten das Fertigungsmodul in einbaufertigem Zustand verlassen.

Für die beschriebene Bohrung holte sich ELHA MAPAL mit ins Boot. Der Werkzeughersteller sollte einen Bohrer liefern, der die Bearbeitung schneller und mit weniger Verlauf und Verschleiß ausführt. Die MAPAL Ingenieure entwickelten daraufhin einen exakt darauf ausgelegten zweischneidigen Vollhartmetallbohrer. Bei den Einsatzparametern vc = 90 m/min und f = 0,5 mm erreicht das neue Werkzeug einen Standweg von 80 Metern und damit fast den dreifachen Weg, den die zuvor eingesetzte Lösung erzielte. Zu den Besonderheiten der gemeinsamen Entwicklung von ELHA und MAPAL zählt auch, dass die Werkstücke in der Spannvorrichtung während der Bearbeitung gegenläufig zur Drehrichtung des Bohrers rotieren, wodurch der Verlauf der Bohrung zusätzlich minimiert wird. Für den Kunden, der pro Jahr bis zu fünf Millionen dieser Bauteile herstellt, ergeben sich dadurch erhebliche Taktzeitvorteile. Zudem benötigt er nur noch eine Maschine, um alle Bearbeitungen zu realisieren.