Operation Manual

18
A7 TIG Orbital System 300© Kemppi Oy 2016 1615
OPERATING MANUAL
3. OPERATION
3.1 Welding settings
3.1.1 Setting current level
Choose weld current after selecting RPM (tungsten speed).
Use the following guidelines:
Carbon
steel
1.3 amps per .025 mm of material to
penetrate.
Stainless
steel
1.0 amps per .025 mm of material to
penetrate.
High alloy
steel
0.75 amps per .025 mm of material to
penetrate.
Above guidelines do not take into consideration ller
wire addition, bevel geometry, or tungsten geometry. They
are based on an electrode moving across a at surface
(typically at a speed of 76 mm/min). When making a 360°
horizontal pipe weld (5G), some current programming
may be needed to counteract the eect of heat buildup. In
some cases, a given start position is mandatory to prevent
concavity at 6 o'clock position.
To avoid current programming or to minimize
programming requirements, use pulsed current technique.
Pulsed current allows the weld puddle to chill and partially
solidify between pulses and provides better control of the
weld puddle. When pulsing, a minimum of 50 % overlap
of the ID bead must be maintained for proper ID bead
reinforcement. Pulse frequency is typically 1 to 10 Hz. A
frequency of 1 Hz is typical for tungsten electrode speeds
of 63 to 90 mm/min.
Increasing tungsten electrode speed above 90 mm/min
requires an increase in pulse frequency to maintain an
appropriate 50 % overlap of ID bead (the solidied bead
from the previous pulse). To obtain high and low pulse
current, use the following formula:
• Average current + (average current/3)
= high-pulse current
• Average current - (average current/3)
= low-pulse current
As a starting point, keep the high and low pulse times
equal (0.3 seconds on, 0.3 seconds o).
Low pulse current is always programmed as a percentage of
high pulse (rather than an actual value). If the weld current
is reduced to compensate for heat buildup in the pipe,
both high and low pulse levels go down proportionally.
• High pulse current programmed on remote
control is actual amperage value.
• Low pulse current programmed on remote
control is a percentage of high pulse current.
3.1.2 Pulsillation (synchronized pulsed current/
oscillation mode)
Pulsed current is automatically synchronized with torch
oscillation whenever the two functions are switched on
simultaneously. This "pulsillation" capability is useful in
certain situations:
• The 2nd or "Hot Pass" can pose special diculties.
• A current level too high will cause re-penetration
of the root pass.
• A level too low will result in lack of sidewall
fusion.
When using the pulsillation mode, the high and low pulse
periods are controlled by the torch oscillator system. High
pulse current occurs during both oscillation stroke end
point "dwell" periods. Low pulse current occurs as the torch
moves laterally across the weld joint. The high and low
pulse controls are not functional when the synchronized
pulsed current/oscillation mode is selected.
3.1.3 Filler wire speed
Filler wire speeds for the root pass are determined by prep
geometry. Typical values for a square butt or a "J" Prep are
25 to 76 cm/min. As the land thickness increases, wire
speed should decrease. Fill-pass wire speeds range from
76 to 190 cm/min. For 360° orbital welding, the higher the
wire speed, the you need to use pulsillation to control the
weld puddle size.