Coolant Hole Configurations

Cutting Fluids

High-pressure coolant (HPC) aids in chip evacuation and helps keep the cutting tool cool and well-lubricated. It is a must for all gundrill operations.

Three types of coolant (cutting fluid) are used in machining operations: straight or neat oil, synthetics and semi-synthetics, and water-soluble or emulsion-style fluids.

As a rule, straight oil provides the best tool life, provided it contains sulfur and/or chlorine. Sulfur’s anti-weld properties help prevent built-up edge (BUE) on the cutting tool, while chlorine acts as a lubricant, further enhancing chip evacuation.

Water-soluble cutting fluids are made up of as much as 50% mineral oil, with the remainder consisting of water, chemicals, and extreme-pressure (EP) additives to enhance lubrication. While these fluids cool more efficiently and are better for the environment than oil-based alternatives, they can reduce tool longevity.

Similarly, synthetic and semi-synthetic fluids are chemical formulations with minimal or no mineral oil content. These fluids typically necessitate concentrations of at least 8%, with 10% being optimal. It is important to note that synthetic cutting fluids may lead to a considerable reduction in tool life when compared to straight oil.

Recommended Coolant Pressures