How to choose the right tap? Guide to chip flutes and chip evacuation

Thread tapping is one of the most important stages of metalworking and at the same time a process that is highly sensitive to errors. Even the slightest irregularities in tool geometry, cutting parameters or chip evacuation can result in tool damage, workpiece deformation or a significant reduction in thread quality. One of the key yet often overlooked elements are chip flutes, which directly determine how effectively chips are removed from the cutting zone.

 

Why are chips a problem?

During machining, chips are generated and must be efficiently removed from the cutting area. When chip evacuation is insufficient, it can lead to:

• tap breakage or pull‑down,
• damage to cutting edges,
• accelerated tool wear,
• deterioration of thread surface quality,
• and even spindle blockage.

 

Residual chips left inside a finished thread can also hinder assembly – a screw may not enter properly, resulting in wasted time and material.

Conclusion: choosing the correct flute type is not a cosmetic decision; it directly affects the efficiency, quality and safety of the tapping process.

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Types of chip flutes and their applications

Taps typically use three main flute types:

• straight,
• spiral,
• straight with spiral point (gun point).

Each of them is optimized for a specific hole type and material behavior. Understanding these differences helps avoid the most common tapping issues.

 

 

1. Straight flutes – a universal solution

Straight flutes are the most common design found in both hand and machine taps. They are suitable for tapping:

• through holes and blind holes,
• at depths of up to approx. 1.5 × the tool diameter.

This design is simple, durable and economical to produce, which is why it is often chosen for standard operations. Straight flutes work best in materials that produce short, broken chips, such as cast iron or brass.

Note: in ductile materials or at greater depths, chip accumulation may occur, increasing the risk of jamming or breaking the tap.

 

2. Spiral flutes – the best choice for blind holes

Spiral (helical) flutes lift chips upward, toward the shank, making them ideal for blind holes.

Characteristics of spiral flutes:

• effective removal of long, continuous chips,
• a clean cutting zone,
• reduced spindle load,
• tapping capability up to 2.5 × thread diameter,
• excellent performance in structural and stainless steels.

 

3. Spiral point flutes – for through holes and long‑chipping materials

Spiral point flutes push chips forward, ahead of the tool, rather than pulling them upward. For this reason, they are used primarily in through holes. They perform best in materials that produce long, spiral chips:

• steels
• aluminum alloys
• copper
• bronze

Operating rule: the tap should only be retracted once the angled rake face has completely exited the hole. This prevents chip pull‑back and incomplete thread formation.

This flute type enables tapping at depths of up to 3 × the tool diameter.

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How to choose the right flute type?

Choosing the correct flute geometry depends on three key factors:

• Hole type – through or blind
• Tapping depth
• Material behavior and chip type

In practice, the operator should always begin by identifying the hole type and depth. The next step is to select the flute type that ensures safe and efficient chip evacuation.

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800X taps – universal for a wide range of applications

Taps from the 800X series are designed for machining a variety of materials, from carbon steels to stainless steels. Made from HSSE steel with 5% cobalt, they offer excellent cutting‑edge stability and high wear resistance.

The dual‑layer PVD TN2 coating (TiAlN + TiN) reduces friction, increases durability and improves heat dissipation.

This makes them a popular choice among operators who need one versatile tool for everyday tasks, regardless of hole type or material. The wide range includes taps for through holes, blind holes and extended‑shank versions for hard‑to‑reach features.

 

MasterTap taps – precision for demanding applications

The MasterTap series is engineered for high‑performance tapping in demanding industrial environments. These tools are made from HSSE‑PM powder metallurgy steel, providing exceptional material homogeneity and outstanding wear resistance.

Advanced PVD coatings and innovative microgeometry allow MasterTap taps to excel not only in standard steels but also in difficult‑to‑machine materials such as titanium alloys or heat‑resistant superalloys.

Available variants (spiral, skewed, straight flutes, as well as internal‑coolant versions) allow precise matching of the tool to the hole type and chip evacuation direction. It is a solution appreciated by technologists and CNC operators who demand repeatability and process reliability.

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Summary

Choosing the right flute type is not a minor detail but a key element of successful tapping. With properly selected tool geometry, you can significantly extend tool life, improve thread quality and minimize the risk of failure. Both the universal 800X and the high‑performance MasterTap series demonstrate that flute geometry is far more than a design detail, it is a factor that determines the quality of the entire operation.

 

Looking for the best tap for your material? Contact us and explore the full FANAR product range