11.05.2023

A strategy for battery frames

The complete machining of parts has to be well thought out, every step coordinated with the next. This is the only way to attain reliable and cost-effective manufacturing with perfect results. To provide customers with such sophisticated strategies, MAPAL has defined focus components on electric cars and worked out the optimal machining strategy for them. The battery frame is one of these components.

#Products #Industries #Automotive #E-Mobility #Milling
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    The solid carbide milling cutter OptiMill-SPM-Finish finishes large pockets in a single pass. ©MAPAL 

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    The generic component presents the challenges involved in machining a battery frame. ©MAPAL 

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    The specially designed PCD milling cutter machines both bores with different diameters. ©MAPAL 

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    Took an in-depth look at battery frames at MAPAL and their optimal machining strategy (from left to right): Andreas Wolf (Test Engineer), Florian Hofmeier (Component Manager Driveline) and Michael Kucher (Component Manager E-Mobility). ©MAPAL 

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    In total, seven tools are employed by the generic process to machine the battery frame. ©MAPAL 

The battery frame is a crucial part in every electric car. It usually consists of various frame elements that are welded together after pre-machining and act as the battery’s enclosure. Based on various customer parts, MAPAL’s electric mobility experts have put together a generic component that encompasses the main machining operations of a battery frame. “With this part, we highlight the special challenges involved in machining”, says Michael Kucher, Component Manager E-Mobility at MAPAL.


The challenges faced while machining the part include stepped bores, bores with different diameters through multiple layers, milled pockets with varying dimensions, shoulders, and high demands on the resulting surface.

The generic component presents the challenges involved in machining a battery frame.   ©MAPAL
“We master these challenges above all with the optimally designed milling cutters”, says Kucher. Milling is even used for most bores on the frame part. Depending on diameter and machining depth, the experts decide in each case whether to drill or mill. “While the cycle time during the milling of bores is somewhat longer, milling offers decisive advantages in this case, which more than make up for the lost time.” In the past, long chips which occurred while drilling aluminium parts often proved very problematic to customers. “Removing long chips from inside the frame part presented a risk for the process”, says Kucher. The short milling chips are easy to remove. There is also a lot less burr formation during milling than drilling. And there is no need for tools changes. Multiple bores with different diameters can easily be machined with a single milling cutter.

This advantage is brought to bear particularly when a bore has a larger diameter in one of the lower layers than the bore entrance at the top layer. “This can be done effectively with a reverse cutting edge on the milling cutter”, says Kucher. The alternative would be reclamping the workpiece in order to machine the bore from the bottom with a drill. A specially designed PCD milling cutter from MAPAL machines the bore at a spindle speed of 16,000 rpm, a cutting speed of 650 m/min and a feed of 0.063 mm.
 
In total, seven tools are employed by the generic process to machine the battery frame  ©MAPAL

Optimal surfaces with the OptiMill-SPM-Finish

Um die Absätze, Taschen und Nuten zu schruppen und die Taschen zu schlichten, empfiehlt MAPAL den OptiMill-SPM-Finish. „Er erreicht bestmögliche Oberflächen und arbeitet auch in den Ecken bei großer Umschlingung und hoher Belastung stabil“, beschreibt Kucher das Werkzeug. Die Spanräume sind poliert, damit funktioniert die Spanabfuhr perfekt. Das Besondere an diesem Werkzeug ist, dass Anwender große Tiefen in einem Zug schlichten können. Das spart Zeit und ist damit besonders wirtschaftlich. Beim Schlichten am Batterierahmen wird eine Oberfläche von bis zu Rz = 1 µm erreicht. Beim Schruppen wird mit einer Drehzahl von 10.981 min-1, einer Schnittgeschwindigkeit von 414 m/min und Vorschüben zwischen 0,12 und 0,22 mm gearbeitet. Beim Schlichten mit gleicher Drehzahl und gleicher Schnittgeschwindigkeit beträgt der Vorschub 0,075 mm. 
Der speziell ausgelegte PKD-Fräser bearbeitet die beiden Bohrungen mit unterschiedlichen Durchmessern.   ©MAPAL
Insgesamt kommen für den gesamten Musterprozess sieben Werkzeuge – davon sechs Fräser zum Einsatz. Neben dem OptiMill-SPM-Finish unter anderem der jüngst vorgestellte FaceMill-Diamond-ES. Um ein perfekt aufeinander abgestimmtes System zu bieten, werden alle Werkzeuge mit Zylinderschaft für den Musterprozess in UNIQ Spannfuttern gespannt.  
  
„Wir bieten unseren Kunden für die Herausforderungen beim Zerspanen des Batterierahmens ein Komplettpaket an – bestehend aus PKD- und VHM-Werkzeugen, Spannfuttern und dem entsprechenden Prozess. Dafür passen wir den Musterprozess individuell auf die jeweiligen Gegebenheiten an“, erläutert Kucher.  
 

MAPAL Lösungen für die Elektromobilität
Kathrin Rehor, PR Project Manager at MAPAL

Contact

Kathrin Rehor Public Relations Kathrin.Rehor@mapal.com Phone: +49 7361 585 3342

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