smart machining with abrasive waterjets (awj) · smart machining with abrasive waterjets (awj)...
TRANSCRIPT
Smart Machining with Abrasive Waterjets (AWJ)
Mohamed HashishFlow International CorporationKent, WA 98032
Overview
• Background
• Discuss factors that affect results and robustness
• Discussions will revolve around the tetrahedron with more focus on the process technology
• Examples of smart machining for selected applications
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AWJ System Platforms
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Smart machining addresses all the platforms
5 Platforms
Smart Pumps
• Pump selection• Hyperjet: 94 Ksi Max pressure
• 87 Ksi operating pressure
• Hyperlife: 75 Ksi Max pressure
• Standard: Max pressure 60 Ksi
• Direct drive: Max 60 Ksi high efficiency
• Pump monitoring and diagnostics
• Ease of maintenance
• iOT
• Pressure profiling
• Networking
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Results- Geometrical- Integrity
- standoff distance- traverse speed- lead angle- taper angle
- pressure- orifice size- mixing tube diameter- mixing tube length- abrasive material- abrasive flow rate- abrasive particle size
Jet
Para
met
ers
Kin
emat
ic
Para
met
ers
• Optimize• Static variables
• Orifice size
• Mixing tube length
• Mixing chamber shape
• Abrasive particle size
• Abrasive material
• Monitor• Quasi static variables
• Orifice edge
• Mixing tube diameter
• Control• Dynamic variables
• Pressure
• Abrasive flow rate
• Cutting speed
• Jet angles
• Stand off distance
Smart Process
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Cutting Observation
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Process Models
Basic Model areas• Jet-Material Interaction• Wear Models• Multi Phase flow
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Static Parameters
Parameters Controls
Orifice size • Orifice size is specified to +-.0002
Water supply tube • High l/d for jet coherency >20
Mixing tube length • Specified to +- 0.005
Abrasive particle size• Supplier size distribution
specification – less fines
Abrasive material• Supplier material specification• Application needs
Abrasive feed line length• Minimal from metering valve to
nozzle – no kinksAbrasive feedline material
• Polyurethane• Minimal friction
Abrasive feedline diameter
• Optimized for the abrasive flow rate range
Mixing tube tip cone• Minimal face area to prevent
abrasive rebound
Jet-mixing tube alignment
• High concentricity > 50% at exit• Pre-aligned Cartridges
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Quasi Static Parameters
ParametersControls/sensor
examples
Orifice edge• Vacuum sensor • Air flow rate below orifice
Inlet mixing tube diameter
• Air flow measurement • Periodic inspection
Exit mixing tube diameter
• Vision • Periodic gauging• Compensation
Inlet air flow rate• Venturi• hot wire anemometry
Inlet air condition• Air condition control
(heating, drying)
Temperature (room and catcher)
• Needed for the room, catcher, and fixture
Mixing chamber wear• Hard materials inserts• Periodic Air flow
measurement
0
100
200
300
400
500
600
700
800
0 5 10 15 20 25 30 35 40
Air Flow Rate (Liter/min)
(Pa
- P
v)
mm
-Hg
AWJ Nozzle
Characteristics
Abrasive Feed Hose
Characteristics
dn=0.457 mm, dm=1.19 mm, lm= 76 mm, lh= 3.05 m
69 MPa
138 MPa
207 MPa
276 MPa
dh= 2.54 mm dh= 2.54 mm
dh= 3.81 mm
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Dynamic Parameters
Parameters Controls
Jet pressureA pressure transducer near cutting head is sometimes used
Abrasive flow rateSelected using an orifice or rotary drum - No feed back control
Lead anglePredicted and machine-controlled to 0.2 degrees
Taper anglesPredicted and machine-controlled to 0.02 degrees
Cutting speedPredicted and machine-controlledto +- 3% with acc-dec flow slowing around corners
Stand off distanceControlled within 0.005 inch with height setters- Dynamic contour followers
Catcher water temperature
Catcher temperature control is required and implemented for some applications
SOD Control
Focal pointTaper control
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More Examples
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More Examples
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Abrasives
Dual abrasive feed metering and mixing mini hoppersUS Patent No: 8,308,525
Al2O3
abrasivesGarnetabrasives
metering
Mixing
MaterialMohs
HardnessKnoop
HardnessSpecific gravity
Diamond 10 7000 3.51
Boron Carbide 2750 2.52
Silicon Carbide 2480 2.2
Titanium Carbide 2470
Aluminum Oxide 2100 1.95-4.0
Tungsten Carbide 1880 15.6
Titanium Nitride 9 1800
Tungsten Carbide 1600
Garnet 1360 3.4 - 4.3
Topaz 8 1340
Zirconia 1160
Steel grit 750 7.8
Quartz/Silica 7 820 1.2
Glass beads 530 1.04
Olivine 6.7 1.5
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Drilling Examples
• Diameter (d) ~ 0.015 inch• Angle ~ 22 degree• Size accuracy ~ 0.001 inch• Spacing ~ d• depth ~ 25 d• Thousands of holes have been
drilled in CFRP and TBC• Acoustic sensing is used to detect
hole breakthrough
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Milling Example
• Damaged composites can be scarfed at shallow angles to create a new surface for bonding
Jedo Technologies, France, 3D Milling examples
Scarfed surface and batch repair
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Surface Integrity Results
Controls
Frosting
• Frosting is eliminated when
cutting under water or using
coherent jets
Embedding• Final conventional finishing
• Pure waterjet pass
Delamination
• Vacuum assist
• Pressure ramping
• Optimal parameters and
Procedures
Chipping/cracking
• Vacuum assist
• Pressure ramping (thick)
• Optimal parameters and
Procedures
Tear drop
• Tilt while drill
• Optimal parameters and
Procedures
Bur• Support
• Grit size
Qualitative Results
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Summary
• Smart Machining with AWJ addresses:• Applications
• Process Technology
• Equipment platforms
• Materials optimization
• Management of environmental effects
• There is a significant knowledge and advances is sensors, controls, and software to propel AWJ to the next industrial revolution
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Thank you!
Mohamed Hashish
Flow International Corporation206-465-5953
www.Flowwaterjet.com
Questions Please