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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