Should ACP use single flute up cut or down cut?

Single-flute left-hand spiral milling cutters are generally recommended. Why are single-flute left-hand spiral milling cutters recommended?
1,To prevent tearing and lifting of the aluminum surface:

Aluminum composite panels consist of a thin layer of aluminum (usually 0.1-0.5mm) on the surface and a plastic core in the middle. During cutting, if the milling cutter rotates upwards (right-hand spiral), it can easily lift the already cut thin aluminum layer upwards, causing the aluminum layer to separate from the core material at the edge of the cut, resulting in burrs, curling, or lifting.

A left-hand spiral milling cutter rotates downwards, creating downward pressure during cutting, pressing the aluminum layer against the core material, resulting in a clean, flat, burr-free, and peel-free cut. This is crucial for curtain wall panels and decorative panels that require high surface quality.

2,Improved chip evacuation:

The downward cutting force of the left-hand spiral milling cutter helps to push the chips (especially the soft plastic core material chips) downwards, rather than flying upwards or wrapping around the tool, which helps keep the processing area clean.

3,Suitable for finishing and thin sheets:

For processing requiring high precision and high-quality edges (such as grooving and contour cutting), a left-hand spiral cutter is the preferred choice. For thinner aluminum composite panels (such as 3mm and 4mm), using a left-hand spiral cutter can significantly reduce processing damage.