Milling instead of drilling

The fastest way to drill a bore is using a suitable drill. A milling cutter with a smaller diameter that enters the material circularly covers a significantly longer distance during machining, which results in a higher cycle time. However, certain materials can cause non-productive times that cancel out the drill’s time advantage.

During the course of the transformation to e-mobility, welded designs or structural parts are to be machined that consist of long-chipping aluminium. Battery housings, for example, are often made from extruded profiles that contain either no silicon at all or only a very small amount. That makes chip breaking more difficult and leads to nests of chips that can get stuck in the machine or on the tool. The same problem comes up when machining chassis parts made of forged aluminium, where manufacturers also struggle with long chips. If they settle on the shank of the tool, an automatic tool change may no longer be possible. Chip clusters cause disruptions that have an adverse effect on the machining time.
 

Especially during drilling from solid or certain boring operations, a burr can form which is pressed out and wraps around the tool as a ring. “These rings accumulate at the tool cutting edge and can damage the workpiece and the tool”, confirms Leander Bolz, Sales Manager of PCD Tools.

In principle, drills can be equipped with chip breakers, but these usually impair the tool life. In addition, with the materials used, it is not always guaranteed that the chip breaker will reliably do its job. Aluminium with a low silicon content can display different properties depending on cast, batch or the storage condition, which is also reflected in different chip formation. This means that in practice the stock removal situation of the pre-machining is often changed. While blades or entire tools sometimes have to be replaced with a drilling tool, the stock removal with a milling cutter can easily be reduced or increased via the driven tracks.
 

このフライス加工戦略は、異なる直径の穴が必要な場合にもその柔軟性を発揮します。 これには 1 つのフライスカッターを使用できます。 より大きな穴加工の場合、前加工のために 1 つまたは 2 つのドリルを交換する必要がなくなります。 MAPALでは、ドリル加工に比べて初期性能の欠点を補う、特に前加工時の時間を節約できるため、対象の材料にフライスカッターを使用することを推奨しています。 特定のワークピースでは、例えば構造部品の薄壁に穴あけにより変形の危険性がある場合や、シャーシ技術で非常に特殊な粗さの穴加工が必要な場合など、フライスカッターは初めから優れています。

Leander Bolz 氏が説明するように、複合工具を使用するとサイクル タイムがさらに短縮されます。「フライス加工が工具の前面で行われ、精密機械加工がその後で行われる場合、穴は 1 回のパスで完全に作成できます。」 さまざまな形状から選択できるツールは、それぞれの加工作業に適応します。 MAPALは、アルミニウム加工用の PCD 刃先を備えた SPM フライス カッター(構造部品加工) を提供しています。 これらの非常に頑丈に設計された大量生産用フライスカッターは、もともと航空宇宙産業向けに固体から材料を機械加工するために開発されました。