1 Flute DOWN CUT Carbide End Mill

A 1 flute down cut end mill is a versatile cutting tool suited to a range of materials, including aluminium composite material (ACM), plastics, and wood. It works on the same principle as a 2-flute down cut but runs a single cutting edge, which clears chips more freely and leaves more room in the flute — useful in softer, gummy materials and at higher feed rates. The down-cut geometry pushes chips back down into the material as it cuts, holding the top surface down and delivering a clean, splinter-free top edge. That makes it especially good for materials prone to chip-out or lifting, such as laminates, veneers, and coated composite panels.

Because a single flute removes more material per revolution, this bit runs cooler and resists chip re-cutting and melting in plastics — a common problem when a 2-flute packs the slot with heat. As with all down-cut tooling, chips are forced downward rather than ejected, so they can pack into the bottom of deeper slots; it’s at its best on thinner stock, shallow pockets, and single-pass profiling. Like other down-cut bits, it suits relatively softer materials with lower cutting forces and gives its cleanest results on the top face of the workpiece.

Suitable for

• Plastics (ABS, acrylic, HDPE etc.)
• Aluminium Composite Materials (ACM/ACP)
• Timber, plywood, and veneered or laminated panels where a clean top edge matters

Not ideal for

• Deep slotting or deep pockets — chips pack into the bottom of the cut rather than clearing; step down in shallow passes instead
• Thick or solid aluminium — the higher cutting forces suit a dedicated aluminium up-cut, which lifts chips clear of the cut
• Jobs needing a flawless bottom edge — down-cut geometry favours the top face and can chip out on the underside of thin, unsupported stock

Adam’s Tips

When cutting aluminium composite panel with a CNC machine, the number of passes needed can depend on the rigidity of the machine. Depending on the rigidity of your CNC machine, you may be able to cut the material in one or two passes.

Another consideration when cutting aluminium composite panel is the diameter of the end mill bit. If you find that using a smaller diameter bit (such as 2mm) results in an excessive amount of plastic chips packing back into the slot, you may want to try using a 1-flute up cut end mill for aluminium. This type of end mill forces chips up and away from the material being cut, which can help to reduce the clean-up time. Keep in mind that the up-cut bit will put the chips on top of the material, which may create a mess if not handled properly.

With a single-flute down cut in particular, keep the feed rate up — these bits rely on a decent chip load to run cool and clear properly. If you’re getting melted plastic or a rough edge, the fix is usually a faster feed or a lower RPM, not the other way around. And because chips are pushed down into the cut, clear deeper slots in a couple of stepped passes so they don’t pack in the bottom.