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

This guide focuses on tool selection for plastics and soft materials, including aluminum and composites. For general flute count selection in harder 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, composites, 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
• Aluminum and other soft non-ferrous materials
• High-speed routing where heat control and edge finish are critical

Considerations

• Optimized for clean cuts in thermally sensitive materials
• Superior melt prevention and chip evacuation compared to standard designs

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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 and soft materials 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 in many cases)	Excellent	Limited
Heat Control	Good	Best	Poor
Best Materials	Soft metals (e.g., aluminum), wood, plastics, composites (design dependent)	Plastics, aluminum / soft metals	Steel, harder alloys

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Browse Related Collections

Single-Flute End Mills

O-Flute End Mills