welding stt technology
DESCRIPTION
STT technologyTRANSCRIPT
STT® Controlled Short Circuit Transfer
– Surface Tension Transfer – a recent innovation
Different from conventional CV processes
STT® is neither constant current (CC) nor constant voltage (CV)
Real time (closed loop) adjustment and control of welding output
waveform
STT ® output response is arc event driven, not time event driven as
in a conventional pulse machine)
Capable of changing electrode current in microseconds
Surface Tension TransferSurface Tension Transfer
How does it work?How does it work?
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
ComparisonComparison
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
October, 98 Waveform 4
STT vs Short Arc
175 IPM , 0.045 ER70S-3, CO2, 1 second exposure
EquipmentEquipment
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Pinch area
How does it work?How does it work?
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Waveform Control TechnologyWaveform Control Technology
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Background current (T0 – T1)
– This is the current level of the arc prior to shorting to the weld pool it is a steady current level between 50 – 100 amps
Waveform Control TechnologyWaveform Control Technology
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Ball time (T1 – T2)
– When the electrode initially shorts. The background current is further reduced to 10A for approximately 0.75 m/s
Waveform Control TechnologyWaveform Control Technology
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Pinch mode (T2 – T3)– Following the ball time, a high current is applied to the shorted
electrode in the form of an increasing , dual-slope ramp. This accelerates the transfer of the molten metal from the electrode to the weld pool by applying electric pinch forces
Waveform Control TechnologyWaveform Control Technology
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
dv/dt value (T2 – T3)
– When this value indicates fused separation is about to occur, the current is reduced to 50A in microseconds
Waveform Control TechnologyWaveform Control Technology
Pinch area
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Separation (T4)
– Indicates the separation has occurred
– But at a low current
Waveform Control TechnologyWaveform Control Technology
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Plasma boost (T5 – T6)
– A period of high current where the electrode is quickly melted back immediately after separation of the electrode from the weld pool
Waveform Control TechnologyWaveform Control Technology
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Plasma (T6 – T7)
– The arc current is reduced from plasma boost to background current.
Waveform Control TechnologyWaveform Control Technology
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Background Current (T0 – T1):
– Controls bead shape and provides minimum heat to maintain a liquid ball
Peak Current (T5 – T6):
– Controls arc length and promotes good fusion
Tailout (T6 – T7):
– Reduces puddle agitation, eliminates premature shorts, and aides wash-in of
the weld bead
Waveform Control TechnologyWaveform Control Technology
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
Root Pass ApplicationsRoot Pass Applications
Semi-automatic or automatic applications
Shielding gases:
– 100% CO2 for mild steel
– Ar/O2, Ar/CO2, Ar/He for stainless steel
STT
5.0 mm
2.5 mm
STICK
Weld size– 50% thicker ligament
thickness– No trapped slag– No fusion defects
Application Advantages– High quality / low defect rate– Low hydrogen deposit– High productivity rate– Easily automated – Less skill requirement
Surface Tension Transfer – STT®Surface Tension Transfer – STT®
AdvantagesAdvantages
October, 98 Waveform 18
STT Replacing Short-arc
• Advantages¨ No Cold Fusion¨ Consistent X-ray Quality Welds¨ Good Puddle Control¨ Shorter Training Time¨ Low Fume Generation¨ Low Spatter¨ Not Sensitive to Composition of Shielding Gas
Reliable
October, 98 Waveform 19
STT Replacing TIG
• Advantages¨ 4 Times Faster¨ Vertical Down Welding Possible¨ Shorter Training Time¨ Not Sensitive to Composition of Shielding Gas¨ 100% CO2¨ Welds Stainless, Nickel Alloys and Mild Steel Well
High Speed
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Copyright 2000 Lincoln Global Inc.
MM-41
Surface Tension Transfer (S.T.T.)
• Controlled Heat Input• Minimal Spatter• Use Wire Size Larger
than Normal• Minimal Smoke• All Positions• Low Cost Gas• Good Fusion• Handles Poor Fit Up
• More Expensive Equipment• Limited to a Modified Short
Circuit Mode
Advantages Limitations
Questions?Questions?