TPT May 2008

114 / 132

Tube & Pipe Welding: Trends & Progress
M ay 2008 112 ›
Miller Electric Mfg Co, USA, has introduced
the new Maxstar ® 350 DC TIG/Stick inverter
to improve DC TIG welding productivity and
quality in industrial applications.
Compared to the previous model, the
Maxstar 350 TIG welder offers high-speed
pulsing capabilities – now up to 5,000
pulses per second, which is a ten-fold
improvement. It also offers 50 amps more
welding power and is more robust.
The Maxstar 350 delivers 5-350 amp output
(300 A at 32 V, 60 per cent duty cycle),
weighs 135.5lb and features Auto-Line
technology, allowing it to run from any input
power, 208 to 575 V, single- or three-phase.
A single, full-featured Maxstar 350 model
has replaced three previous models. An
easier-to-understand front panel controls
basic TIG welding functions, while a
secondary menu controls additional setup
parameters and values.
The Maxstar 350 is available as a stand-
alone unit, as a TIGRunner package
featuring the Coolmate 3.5 cooler and
a TIGRunner package with cooler and
Weldcraft water-cooled torch.
The Maxstar 350 enables users to adjust
the number of pulses per second (PPS)
from 0.1 to 5,000 PPS. It also enables
control of the amount of time each pulse
cycle spends at peak amperage from 5 to
95 per cent of total cycle time. Users can
set the background or ‘low’ current pulsing
value to between 5 to 99 per cent of peak
amperage.
Pulsing in excess of 40 PPS increases
weld puddle agitation to create a better-
as-welded microstructure. Pulsing the weld
current at 100 to 500 PPS also constricts
and focuses the arc. This maximizes
arc stability, increases penetration and
increases travel speeds.
Pulsed welding also lowers heat input and
reduces the size of the heat-affected zone
(HAZ). Typical applications include stainless
steel, nickel alloys and other metals
where excess heat can lead to warping or
degrading metallurgical composition (eg
carbide precipitation).
In automation applications, which require
maximum travel speeds, pulsing at
frequencies beyond 500 PPS can further
enhance arc stability and concentration.
Miller Electric Manufacturing Co – USA
Fax: +1 877 327 8132
Email:
Website:
High-speed pulsing capability with
new 350 DC TIG welder
 The new Maxstar 350 DC TIG/Stick inverter
offers high speed pulsing capabilities (up to
5,000 pulses per second)