The Influence of High Pressure Coolant on

Process Optimization in Heat Resistant

Super Alloys (HRSA)

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By: Sean Holt, Aerospace Manager - Americas

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The History of High Pressure Coolant (HPC)

1984 1990 1996 2007 2012

Multi-task

Machining center

Turning center

Pre

ssure

bar

(psi)

500

(7250)

100

(1450)

Ccoupling for UHPC

VTL

Standard coupling

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High Pressure Coolant Definitions

High Pressure Coolant (HPC)

up to 80 bar (1160 psi)

– Standard option on most machines

• Turning centers

• Machining centers

• Multi-task machines

– Standard Coromant Capto® coupling

– Standard Sandvik Coromant tools available

Ultra High Pressure Coolant (UHPC)

over 80 bar (1160 psi )

– Standard option for a few machine manufacturers

• Limited to VTLs

– Coromant Capto® coupling for UHPC

– Tool holders only as special

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Pressure (p) Force per unit area

– Pascal = N/m2

– Bar = 0.1 MPa (14.5 psi)

Flow rate () Volume displaced per time unit

– liter/min (gallons/min)

Velocity (w) Speed fluid moves through a tube

– m/sec (ft/sec)

High Pressure Coolant Definitions

K

k

()

(w)

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High Pressure Coolant Challenges in machining

Operation differences:

Turning – continuous single point

– Cutting temperature

– Chip control

Milling – interrupted multiple teeth

– Chip formation

– Cutter positioning

– Re-cutting of chips – unsecure or short tool life

Drilling – continuous multiple teeth

– Varying cutting temperature

• hot periphery

• tough center

– Chip control and evacuation through flute

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HPC – System requirements

Pump/machine

– Pressure

– Volume/flow rate

– Filter

Tool

– Nozzle diameter

– Number of nozzles

– Jet flow

– Jet direction

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HPC – System requirements Principles

Reducing the area

increases the velocity

Smaller outlet reduces the

pressure and flow rate

requirements to achieve a

high velocity jet

Flow

velocity w1

Flow

velocity w1 w2

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Flow expressed in m3/s

CD Nozzle efficiency - 80% 20 to 300 bars (290-4350 psi)

- 70% 300 to 1000 bars (4350-14500 psi)

n Number of nozzles

d Nozzle diameter (m)

p Pressure (Pa) - 1 bar (100 000 Pa)

- 1 psi (6895 Pa)

Fluid density - for water and

cutting fluids the density is

~ 1000 kg/m3

HPC – System requirements Flow requirement

The larger the outlet area the greater the flow required to deliver a given pressure

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Coromant Capto®

Normal coolant inlet

• Hydraulic wedge lifts the chip

• Reduces temperature

• Improves chip control

High precision jet nozzles

Pre-defined target areas on

the insert face

HPC – Turning applications Precision is the power

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With CoroTurn® HP 80 bars (1160 psi)

– Metal removal +50 at same speed

– Cutting speed +20% with same total metal removal

HPC – Turning applications Inconel 718 (46HRC) -Total material removed (TMR)

Insert ap fn

CNMX 1204A2-SM S05F 2.5 mm 0.3 mm/rev

CNMX 43A2-SM S05F 0.1 inch 0.012 inch/rev

To

tal m

ate

ria

l – Q

(c

m3)

Surface cutting speed –

Vc (m/min), ft/min

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Normal Pressure 80 bar (1160 psi)

HPC – Turning applications Inconel 718 (46HRC) - Chip control

Insert vc

CNGG 120408 -SGF1105 65 m/min

CNGG 432-SGF 1105 213 sfm

Feed

fn (mm/rev)

Cutting depth

ap (mm)

0.15 0.2 0.25

2.0

1.0

0.5

0.25 Feed

fn (mm/rev)

Cutting depth

ap (mm)

0.15 0.2 0.25

2.0

1.0

0.5

0.25

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UHPC – Turning applications The basic concept of the technique

UHPC tool - coolant supplied externally

into the Coromant Capto® coupling

UHPC blanks - prepared with four

sealing seats

80-1000 bar (1160-14500 psi)

HPC tool – internal coolant supply

through Coromant Capto ® polygon

80 bar (1160 psi)

Coolant inlet UHPC HPC

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UHPC - 230 bar (3300 psi) – 3 mins Normal coolant – 3 mins

UHPC - 300 bar (4350 psi)

UHPC – Turning applications Effect on Inconel 718

UHPC - 150 bar (2200 psi)

Summary

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Introduction and history of High Pressure

Challenges in Machining

– Operational differences

HPC System requirements, benefits &

considerations

HRSA machining results & difference with

other materials

Future trends & directions

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