Choosing Single-Flute and O-Flute End Mills for Plastics & Soft Materials

This guide focuses on tool selection for plastics and soft materials. For general flute count selection in metals, see the 2-Flute vs 3+ Flute guide under "Guides & Charts".

Choosing Single-Flute and O-Flute End Mills for Plastics & Soft Materials

Single-flute and O-flute end mills are commonly used for plastics, aluminum, and other soft materials where chip evacuation and heat control are critical.

This guide explains the practical differences between single-flute, O-flute, and multi-flute tools so you can choose the correct option based on material behavior and flute design — not just flute count.

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Why Flute Style Matters in Plastics and Soft Materials

Soft and gummy materials behave differently than steel. Chips can melt, weld to the tool, or re-cut if they are not evacuated efficiently.

In these materials, flute shape, rake angle, and available chip space often matter more than the total number of flutes.

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Single-Flute End Mills

What they are

• One cutting edge with a dedicated chip path
• Available in both straight-flute and spiral (helical) designs

Straight-flute single-flute tools

• Large, open chip space
• Well suited for wood, soft plastics, foams, and composites
• Excellent chip evacuation for bulky or fibrous materials

Spiral (helical) single-flute tools

• More controlled cutting engagement
• Reduced flute volume compared to straight-flute designs
• Better suited for aluminum and soft non-ferrous metals than wood

Considerations

• Not all single-flute tools evacuate chips equally
• Wood and fibrous materials benefit most from straight-flute designs
• Spiral single-flute tools may pack chips in wood if feed rates are not managed carefully

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O-Flute End Mills

What they are

• A specialized single-flute design
• High rake angle with a polished flute surface

Best used for

• Plastics such as acrylic, HDPE, and polycarbonate
• High-speed routing where heat control matters
• Applications where edge finish is critical

Considerations

• Optimized for plastics, not general metal cutting
• Superior melt prevention compared to standard single-flute tools

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Multi-Flute End Mills (2+ Flutes)

While multi-flute end mills excel in harder materials, they are generally less suitable for plastics due to reduced chip space and higher heat buildup.

For plastics and soft materials, multi-flute tools are typically reserved for:

• Light finishing passes
• Rigid setups with conservative feed rates

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Quick Comparison

Feature	Single-Flute	O-Flute	Multi-Flute
Chip Space	Varies by design	Excellent	Limited
Heat Control	Good	Best	Poor
Best Materials	Aluminum, plastics (design dependent)	Plastics	Steel, harder alloys

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Browse Related Collections

Single-Flute End Mills

O-Flute End Mills