What are the advantages of through coolant drills?

In modern CNC machining, where speed, precision, and tool life are everything, through coolant drills have become a must-have for serious manufacturers. But what exactly makes them so effective? Why are more shops moving away from standard drills and upgrading to tools with internal coolant channels?

Let’s break it down clearly—based on real machining problems and proven benefits—so you understand exactly how through coolant drills can help your workshop or production line.

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1. What Are Through Coolant Drills?

A through coolant drill (also called an internal coolant drill) is a cutting tool that has one or more small holes running through its body, allowing coolant to flow from the machine directly to the cutting edges.

Unlike traditional flood coolant systems, which spray fluid externally, these drills deliver coolant exactly where it's needed most—right between the cutting edge and the workpiece. This makes a massive difference in demanding applications.

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2. Top Advantages of Through Coolant Drills

✅ 1. Superior Cooling Performance

Internal coolant delivery drastically improves heat management during drilling. When you’re machining tough materials like stainless steel, alloy steels, or titanium, the cutting zone can reach extreme temperatures. Poor cooling leads to:

• Premature tool wear

• Built-up edge (BUE)

• Surface hardening

With through coolant, heat is reduced at the source, which means the tool stays sharper for longer.

According to Sandvik Coromant, proper coolant delivery can extend tool life by over 50% in deep hole applications.

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✅ 2. Efficient Chip Evacuation

One of the biggest causes of tool breakage—especially in deep hole drilling—is chip packing. When chips can’t escape the hole, they get jammed, build heat, and damage the tool.

Through coolant drills flush chips out of the hole as they’re created. This:

• Prevents chip recutting

• Reduces risk of tool failure

• Improves surface finish

This is especially important when drilling holes deeper than 3xD (three times diameter).

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✅ 3. Longer Tool Life

By reducing heat and friction and keeping the cutting edge clean, through coolant drills significantly increase tool life. This means:

• Fewer tool changes

• Lower tooling cost per part

• Higher machine uptime

Even though they cost more upfront, they pay for themselves over time through improved efficiency.

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✅ 4. Higher Cutting Speeds and Feed Rates

Because of the improved cooling and chip control, you can safely run through coolant drills at:

• Higher RPMs

• Faster feed rates

• Greater depth of cut

That means shorter cycle times and more parts per shift—without sacrificing quality.

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✅ 5. Better Hole Quality

Coolant at the cutting edge helps:

• Minimize workpiece thermal expansion

• Eliminate burrs and built-up edge

• Maintain tighter tolerances

If you're producing precision parts, like aerospace or medical components, through coolant drills are essential for maintaining consistency and quality.

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3. When Should You Use Through Coolant Drills?

These drills are especially effective in:

• Deep hole drilling (over 3xD)

• Hard-to-machine materials (like stainless, Inconel, or titanium)

• High-volume production lines

• Automation, where tool life predictability is critical

If you're still using standard solid drills for deep holes or tough metals, you're likely wasting time, tools, and money.

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4. Common Types of Through Coolant Drills

You’ll find internal coolant technology in various drill types:

• Solid carbide drills (for high-speed, precision applications)

• Indexable insert drills (for large-diameter holes and roughing)

• Step drills and form drills (with complex geometries)

Choose the type based on your material, hole depth, and production volume.

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5. What to Consider Before Switching

Before upgrading to through coolant drills, make sure:

• Your machine tool supports internal coolant (usually requires a coolant-through spindle)

• You’re using the right coolant pressure (typically 20–70 bar, or higher for deep holes)

• Your toolholder is sealed or coolant-capable

If those boxes are checked, you’re ready to unlock a big performance gain.

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Final Thoughts

Through coolant drills aren’t just a premium option—they’re a smart investment for manufacturers who care about precision, tool longevity, and cost efficiency.

At Amony, we specialize in solid carbide and indexable drills with through coolant capability, designed for both general and high-performance CNC applications. If you're looking to upgrade your tools, we’re here to help you choose the right one for your material and machine.