Skip to content

HPC technology

How high-pressure coolant works in CNC machining

High-pressure coolant performance depends on fluid cleanliness, pressure, flow and jet direction. Coolant must reach the chip-formation and heat-generation zone, with delivery synchronised to the machine program.

Configure a unit for your process Send machine details
Research data

Effects of high-pressure coolant: machining trial results

Published experiments point to a consistent mechanism: a jet delivered close to the cutting edge improves heat removal, reduces friction, and helps break and evacuate chips. The magnitude depends on the material, operation, tool geometry, jet direction, flow rate and filtration.

The jet reaches the tool, chip interface

Edge-focused delivery lets coolant enter where an external flood is blocked by the chip. The hydraulic wedge shortens tool, chip contact and reduces friction on the rake face.

Local heat removal increases

Higher jet velocity improves heat transfer at the cutting edge. This matters in Inconel 718 because the work material conducts relatively little heat away from the cutting zone.

Chips are broken and carried away

Jet momentum acts mechanically on the chip. In drilling, through-tool coolant also becomes the transport medium that pushes chips along the flutes and out of the hole.

The process becomes more stable

Fewer jams, less chip re-cutting and smaller thermal swings mean lower transient edge loads, particularly important for long tools and small diameters.

Important: pressure does not increase the geometric EI stiffness of a solid-carbide drill. It stabilises the process indirectly by removing chips, controlling heat and reducing random lateral loads. Core diameter, overhang, flute geometry and clamping still determine actual stiffness.

Flank-wear growth rate in internal boring

Production-representative ST52-3 trial: a shorter bar means slower flank-wear progression.

Production study: ST52-3 steel, vc 220 m/min, ap 3 mm. Feed was also raised from 0.194 to 0.265 mm/rev in the HPC trials, so the result demonstrates process robustness under more demanding conditions rather than the isolated effect of pressure alone. [1]

Forces, roughness and tool life

AISI 1045 turning: change versus conventional flood cooling across the tested cutting conditions.

The ranges cover several speed and feed combinations within one study. They are neither a tolerance nor a guarantee for another work material. [2]

Results for selected machining processes

Drilling Inconel 718 2.05×

Internal cooling versus an external jet

Nitride-coated carbide drills achieved 2.05 times the tool life with internal cooling. The authors also reported lower thrust force, more stable Ra, more accurate hole diameter, and fewer adhesion and smear defects on the bore wall.

Source [3]
Micro deep-hole drilling Ø2 mm

Small diameter does not mean “maximum pressure”

A Ø2 mm solid-carbide single-lip drill in Inconel 718 was tested at 80, 100 and 120 bar. Chips were slightly shorter at 100-120 bar and wear was lower at 120 bar, while force and Ra differences remained small. The researchers selected 100 bar as a stable compromise for further work.

Source [4]
Turning Inconel 718 +740%

Pressure effects depend on cutting conditions

At vc 50 m/min and 203 bar, coated-carbide tool life improved by as much as 740% versus conventional cooling. In the same study, however, 203 bar at vc 20 m/min reduced tool life by 44% because the pressure exceeded the beneficial range for those conditions.

Source [5]

Sources and publications

The charts reproduce values reported by the authors. Results from different materials and operations should not be compared directly or treated as a production guarantee.

  1. Zambom et al. (2026), Through-tool high-pressure coolant in production-representative internal boring
  2. Velan, Shree & Muthuswamy (2021), Effect of cutting parameters and high-pressure coolant on forces, surface roughness and tool life in turning AISI 1045 steel
  3. Qin et al. (2019), A comparative study between internal spray cooling and conventional external cooling in drilling of Inconel 718
  4. Oezkaya, Michel & Biermann (2021), Chip formation simulation and analysis of the mechanical loads during micro single-lip deep hole drilling of Inconel 718
  5. Ezugwu & Bonney (2004), Effect of high-pressure coolant supply when machining nickel-base Inconel 718 alloy with coated carbide tools
  6. Oezkaya, Beer & Biermann (2016), Experimental studies and CFD simulation of the internal cooling conditions when drilling Inconel 718
  7. ISCAR, Drilling Handbook: coolant pressure, flow and internal coolant delivery

When to consider an HPC system

  • Long or tangled chips disturb the process
  • Coolant doesn't reach the bottom of the hole or the cutting zone
  • You need repeatable conditions in unattended operation
  • You want to control cooling from the machine program
  • Standard cooling requires frequent stops to clear chips

What to prepare for selection

  • Machine tool manufacturer and model, and machine type
  • Coolant type (water-miscible / emulsion / oil)
  • Expected pressure and flow (if known)
  • Tools and channel diameters
  • Number of simultaneously used outlets
  • Available M-codes
  • Description of the chip problem

Unit selection

We'll select a unit for your machine and process

Based on this data we'll propose a unit and configuration matched to your process.

Configure a unit for your process Send machine details

Based on this data we'll propose a unit and configuration.