I. Menzies, P. Koshy McMaster University, Canada
Assessment of Abrasion-Assisted Material Removal in Wire EDM
58th CIRP General Assembly, ManchesterAugust 25, 2008
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
generator technology
coated wires
high pressure flushing
adaptive control
workpiece height & taper
surface finish
machining accuracy & precision
1970
Kruth et al (2004)
cutting rate
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Machining speed & surface integrity continue to be issues of focus in current wire EDM research
~40X
Aspinwall et al (2008)
rough
trim
surface integrity
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
The issues of machining speed and surface integrity are interlinked
Aspinwall et al (2003)
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Enhancing the ejection efficiency is the key to simultaneously improving the removal rate and the surface integrity
Need for innovation
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Hybrid machining entails the integration of processes with distinct mechanisms of material removal to exploit their synergy
El-Hofy (2005)
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Grinding + EDMThermal softening of workpiece
In-process dressing & declogging
8/20
Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Extension of the concept to wire EDM
Different from Wire Electro Discharge Grinding
wire rod
discharge area
Masuzawa et al (1985)
9/20
Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
ph > gw
Material removal by melting/vaporization and two-body abrasion
wire
reference voltagedielectric strength
10/20
Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Fixed abrasive diamond wire used in the electronics industry
Issues with wire guide and electrical power feed
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
wire failure by embrittlementexperiments using wire with no abrasives for comparison of removal rate & recast layer, and estimation of gap-width
average voltage 108 –162 V
peak current 1.2 – 8 A
open voltage 180 V
on time 4.9 μs
off time 100 μs
wire tension 6.8 N
wire speed 5.5 m/min
SAE 1018 steel & Nickel 600
dielectric oil; 1 bar flushing pressure
machining gap 8 – 20 µm
removal rate 0.02 – 0.10 mm2/min
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
50 m
180 micron core 50 micron (nominal) diamond
Wire characterization
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Force measurement by considering force equilibrium in reference to wire bow and wire tension
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
edm
Order of magnitude enhancement in the removal ratewire sawing
Steepest gradient in the increase in removal rate is in line with the maximum force gradient
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Increase in the removal rate is due to abrasion
20 m
162 V, 8 A
108 V, 8 A
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
abrasion-assisted
Wire performance degrades rapidly
with repeated use
wire-EDM
108 V, 8 A
Machined surface
used wire
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Comparison of recast material
nickel steel
wire-EDM
abrasion-assisted
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Wire feed strategies
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Conclusions & OutlookProof-of-concept of an innovative abrasion-assisted wire EDM process has been presented
The process has the potential to significantly enhance the removal rate and the quality of the machined surface, particularly for metal matrix composites that are difficult to wire EDM
The process is perhaps best implemented on a twin-wire machine tool
Research effort is required to formulate wires with aluminum oxide abrasives, with a core that has good sparking and grain retention characteristics
Electrical discharges could possibly enhance wire sawing of brittle materials through controlled thermal shock-induced fracture
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Assessment of abrasion-assisted material removal in wire EDMI. Menzies, P. Koshy
58th CIRP General AssemblyManchester, August 25, 2008
Thank you for
your attention! Natural Sciences & EngineeringResearch Council of Canada