Category: Material: Peek

What's the Right Number of Flutes on a Carbide End Mill?

3/19/2024

The number of flutes on a carbide end mill significantly influences its performance across various machining applications. How many flutes do you need? The simple answer: It depends.

Obviously there are a quite a number of other factors that impact an end mills performance such as helix angel, edge prep, gullet depth and radius. We can't tackle everything in this article, but hopefully this helps you get a better understanding of why there are different numbers of flutes on end mills.

Below is an overview of the advantages and disadvantages associated with end mills featuring different flute counts, along with recommendations for materials based on ISO 513 categories (P, M, K, N, S, H)

Single Flute End Mills

Advantages: Single flute end mills are particularly effective for chip evacuation in soft materials, providing excellent clearance. They are also known for their efficient chip removal and reduced deflection, making them suitable for applications requiring high-speed machining and improved surface finishes. Ideal for Routing applications.
Disadvantages: Limited in terms of material removal rates, especially in harder materials. The reduced number of cutting edges may lead to increased heat generation.
Suitability: Ideal for softer materials (ISO P and some ISO M materials) where efficient chip evacuation is crucial, and high-speed machining is beneficial. Suited very well for T-1 through T-4 Aluminum (T is a temper designation that signifies thermally treated aluminum.)

2-Flute End Mills

Advantages: Higher chip clearance, making them ideal for softer materials; less prone to chip clogging.
Disadvantages: Potential reduction in tool life compared to higher flute counts.
Suitability: Best for softer materials (ISO P and some ISO M materials).

3-Flute End Mills

Advantages: Better harmonic balanced performance in terms of chip evacuation and tool rigidity. Suitable for a wide range of materials. As with any odd number of flutes you often have multiple flutes engaged in the cut at the same time.
Disadvantages: Slightly less chip clearance than 2-flute end mills.
Suitability: Versatile; suitable for a variety of materials (ISO P, M, K, N, S, H).

4-Flute End Mills

Advantages: Optimal balance between chip evacuation and tool stability. Higher material removal rates in tougher materials.
Disadvantages: May generate more heat compared to lower flute counts. Less harmonically stable when compared to 3 or 5 flute tools.
Suitability: Versatile; suitable for a wide range of materials (ISO P, M, K, N, S, H).

5-Flute End Mills

Advantages: Enhanced tool stability and surface finish. Ideal for finishing operations.
Disadvantages: Reduced chip clearance in some scenarios.
Suitability: Suitable for finishing operations in a variety of materials (ISO P, M, K, N, S).

6-Flute End Mills

Advantages: Excellent tool stability, reducing deflection and vibration. Well-suited for high-speed machining and finishing.
Disadvantages: Limited chip clearance in certain cases.
Suitability: Ideal for finishing operations and high-speed machining (ISO P, M, S, H)

7-Flute End Mills

Advantages: Improved surface finish, particularly in finishing applications.
Disadvantages: Limited chip clearance.
Suitability: Specialized for finishing in softer materials (ISO P, M, S, H).

8-Flute End Mills

Advantages: High tool stability and reduced deflection. Suitable for finishing and profiling as well as in hard materials.
Disadvantages: Limited chip clearance.
Suitability: Ideal for finishing and profiling in softer materials (ISO P, M, S, H). Often used in High Efficiency Milling (HEM) of nickel-based superalloys.

0-Flute End Mills

Advantages: Exceptional surface finish and stability, especially beneficial for finishing operations.
Disadvantages: Limited chip clearance; potential for clogging.
Suitability: Specialized for finishing in softer materials (ISO P, M, S, H).

Advantages of Higher Flute Counts in
ISO 513 H (Hard Materials)

In ISO 513 H (Hard Materials), end mills with higher flute counts, such as 6, 8, or 10 flutes, demonstrate enhanced performance.

The increased number of cutting edges distributes the cutting forces more evenly, reducing the load on individual flutes and minimizing tool wear. This results in improved tool life and superior surface finish when machining challenging hard materials.

Additionally, the added stability provided by higher flute counts is advantageous in maintaining precision and achieving high-quality finishes in hard material applications.

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Machining Peek: Front & Back Turning, Cut-off, Grooving / Side Turning, and Threading.

4/4/2018

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NTK KM1 Grade Mirror Finish Insert for Front & Back Turning, Cut-off, Grooving / Side Turning, and Threading

A trend that we are seeing develop in many industries, especially in the medical implant device manufacturing sector, is a rise in the number of parts being manufactured from plastics such as Peek. Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family. It was originally introduced by Victrex PLC, then Imperial Chemical Industries in the early 1980s.

Its important to note that PEEK is a thermoplastic. This polymer is capable of being repeatedly softened by an increase in temperature. Increasing the temperature leads to a physical change. That's why cutting tool pressure and heat will impact surface finish and tool life.

The medical industry has found medical-grade PEEK offers excellent strength, wear resistance and biocompatibility for components such as the dental healing caps, spiked washers and spinal implants.

PEEK polymer is available in two basic grades: industrial and medical:

"Industrial-grade PEEK is a strong thermoplastic that retains its mechanical properties even at elevated temperatures. The flame-retardant material is abrasion resistant, has high impact strength and a low coefficient of friction. Industrial-grade PEEK components are used in the aerospace, automotive, chemical, electronics, petroleum, and food and beverage industries.

Medical-grade PEEK possesses those same physical properties in addition to biocompatibility, high chemical resistance and compatibility with several different sterilization methods. It is also naturally radiotranslucent when viewed using X-ray, MRI or computer tomography (CT). Medical-grade PEEK provides doctors with an unobstructed view of tissue and bone growth around the PEEK implant during the healing process. Some implantable-grade PEEK polymers have a bone-like stiffness and can remain in contact with blood or tissue indefinitely."

There is also a glass and carbon-fiber-reinforced PEEK, which offer high wear resistance for components such as articulating joints and tends to wear out inserts rather quickly.

Peek parts are generally very small, ranging from 0.039" to 0.250" in diameter, which adds to the complexity of machining the non-ferrous materials.

Because of the thermoplastic properties, too much heat at the cutting edge results in Built Up Edge (BUE) and tool pressure affects part tolerance.

That where NTK's KM1 grade insert work great. The inserts are extreｍely up-sharp edge and the mirror insert surface creates excellent surface finishes.

NTK KM1 Uncoated grade for CNC Turning Peek

NTK KM1 Grade - uncoated
Up-Sharp Insert Edge - high shearing / reduces heat generation
Mirror Insert Surface - produces excellent finishes on workpiece
Insert Radius - 0.00" up to 0.008"
Ideal features for machining Plastics, Copper, Brass, Aluminum
(see pages O 36-37 in 7100 Catalog)

Things to Remember when Cutting Peek

PEEK shapes are stronger and stiffer than most plastics but considerably softer than most metals meaning fixturing is critical.
Although PEEK has a very high melting temperature sufficient coolant is required during machining to avoid overheating and localized surface melting.

All PEEK grades but especially those reinforced with glass and carbon fiber are abrasive on tooling. Carbide tooling can be used for short runs. Polycrystalline (PCD) tooling should always be considered long runs, tightly tolerance parts and for reinforced grades.

Keys to Succesfull Machining of Peek

1. Limiting Heat Build-up – The softening or melting temperatures of engineering plastics are roughly 1/10th those of metals.

2. Melting or Scorching– The thermal conductivity of plastics is low relative to metals. Most of the heat generated by machining will stay at the surface. Temperatures at the surface can rinse unexpectedly high.

3. Loss of Tolerance – If the overall temperature of the stock changes during or after machining, expansion or contraction can cause the part to fall out of tolerance. Softening of the stock can allow it to deflect at the surface under the pressure of the cutting tool. When the pressure is removed, the stock will recover and fall out of tolerance. This can frequently be managed by using lubricants and changing tooling or speed.

4. Controlling Deflection – Plastics inherently vary in their stiffness (modulus) and are more elastic at higher temperatures. The entire stock can deflect under the pressure of cutting. Proper tooling and support remains important and particular attention should be given to adequately supporting the work.

Additional Resources:

Quoted portions of this article originally appeared in Modern Machine Shop, "A Quick Look At PEEK Machining" by Derek Korn, 6/1/2007
Keys to Success Section from "Machining PEEK Plastics Guide" by Drake Research.

4 Comments

What's the Right Number of Flutes on a Carbide End Mill?

Advantages of Higher Flute Counts in
ISO 513 H (Hard Materials)

Machining Peek: Front & Back Turning, Cut-off, Grooving / Side Turning, and Threading.

Things to Remember when Cutting Peek

Keys to Succesfull Machining of Peek

Additional Resources:

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What's the Right Number of Flutes on a Carbide End Mill?

​Advantages of Higher Flute Counts in​ISO 513 H (Hard Materials)

Machining Peek: Front & Back Turning, Cut-off, Grooving / Side Turning, and Threading.

Things to Remember when Cutting Peek

Keys to Succesfull Machining of Peek

Additional Resources:

Technical Support Blog

Authorship

Archives

Categories

AboutContactTOOLINGWORKHOLDINGEVENTSNEWSTECHNICAL

Find us on Instagram @nextgentool

Advantages of Higher Flute Counts in
ISO 513 H (Hard Materials)

About
Contact
TOOLING
WORKHOLDING
EVENTS
NEWS
TECHNICAL