How Coolant Improves Accuracy and Tool Life in Hole Making

How coolant improves accuracy and tool life in hole making

July 6, 2026
By Sandvik Coromant, for the Blue Print

When manufacturers think about improving drilling and reaming performance, the focus often falls on cutting tools, machine capabilities, or cutting parameters. While those factors certainly matter, coolant is often one of the most influential and overlooked variables in hole making.

A well-managed coolant strategy can improve chip evacuation, control heat, extend tool life, and help maintain dimensional accuracy. In many cases, it is the difference between a stable process and one plagued by poor hole quality and premature tool wear.

Coolant basics

Despite its name, coolant does much more than cool. In drilling and reaming operations, coolant serves three critical functions:

Controls heat at the cutting edge
Reduces friction through lubrication
Removes chips from the hole

Chip evacuation is particularly important because drilling occurs in a confined space. If chips remain in the hole, they can damage the surface finish, increase cutting forces, and shorten tool life. Effective coolant delivery helps move chips away from the cutting zone before they become a problem.

The value of internal coolant

Many modern drills feature internal coolant channels that deliver fluid directly to the cutting edge.

Compared to external flood coolant, internal coolant provides more efficient cooling and chip evacuation, especially in deeper holes where external coolant may struggle to reach the cutting zone. This helps reduce chip recutting, improve hole quality, and create a more stable machining process.

For applications involving stainless steel, alloy steels, or other materials that generate significant heat, internal coolant has become a key contributor to productivity and tool life.

High-pressure coolant systems

For more demanding hole-making applications, high-pressure coolant can provide additional benefits.

By delivering coolant with greater force, these systems help break chips into smaller segments and remove them from the hole more effectively. The result is often better chip control, longer tool life, and fewer interruptions caused by chip packing.

High-pressure coolant can be particularly valuable when drilling difficult materials such as stainless steel, heat-resistant alloys, and other materials that tend to produce long, stringy chips.

Coolant selection and concentration matter

Even the best coolant delivery system will struggle if the coolant itself is not properly maintained.

Coolant concentration directly impacts both lubrication and cooling performance. A mixture that is too weak may not provide adequate protection, while a concentration that is too strong can reduce cooling efficiency and increase operating costs.

Regularly monitoring coolant concentration, cleanliness, and contamination levels helps maintain consistent machining performance and prevents gradual process deterioration that can affect hole quality and tool life.

It's also important to match the coolant to the workpiece material. Different materials generate heat, chips, and cutting forces in different ways, making coolant selection an important part of process optimization.

A practical example

Consider a shop drilling deep holes in stainless steel components. Despite using high-quality carbide drills, tool life remained inconsistent due to chip packing within the hole.

After implementing internal high-pressure coolant, chip evacuation improved significantly. The shop experienced more predictable tool life, reduced downtime, and improved hole quality without changing the cutting tool itself.

This type of result is common. In many cases, coolant optimization delivers substantial gains without requiring major investments in new equipment.

Troubleshooting common problems

When drilling performance begins to decline, coolant should be one of the first areas investigated.

Poor surface finish, excessive tool wear, hole size variation, and built-up edge formation can often be traced back to inadequate coolant delivery, improper concentration, or poor chip evacuation.

Evaluating coolant performance alongside tooling and cutting data can often identify the root cause more quickly and prevent recurring issues.

Summary

Successful hole making depends on more than selecting the right drill or reamer. Coolant plays a direct role in chip evacuation, heat control, dimensional accuracy, surface finish, and tool life.

Whether through internal coolant channels, high-pressure systems, or proper coolant maintenance, optimizing coolant performance can help manufacturers achieve more consistent results, longer tool life, and a more reliable machining process overall.

Content originally from Sandvik Coromant. Reused here with permission.