SECTION 8 − SELECTING AND PREPARING A TUNGSTEN FOR DC OR AC WELDING WITH INVERTER MACHINES

gtaw_Inverter_7/2006

Y Whenever possible and practical, use DC weld output instead of AC weld output.

8-1. Selecting Tungsten Electrode (Wear Clean gloves To Prevent Contamination Of Tungsten)

 

 

Amperage Range - Gas Type♦ - Polarity

 

 

 

 

 

Electrode Diameter

 

(DCEN) − Argon

 

AC − Argon

 

 

Direct Current Electrode Negative

 

Balance Control @ 65% Electrode Negative

 

 

(For Use With Mild Or Stainless Steel)

 

(For Use With Aluminum)

 

 

 

 

 

2% Ceria (Orange Band), 1.5% Lanthanum (Gray Band), Or 2% Thorium (Red Band) Alloy Tungstens

.010” (1 mm)

 

Up to 25

 

Up to 20

 

 

.020” (1 mm)

 

15-40

 

15-35

.040” (1 mm)

 

25-85

 

20-80

1/16” (1.6 mm)

 

50-160

 

50-150

3/32” (2.4 mm)

 

135-235

 

130-250

1/8” (3.2 mm)

 

250-400

 

225-360

5/32” (4.0 mm)

 

400-500

 

300-450

3/16” (4.8 mm)

 

500-750

 

400-500

1/4” (6.4 mm)

 

750-1000

 

600-800

 

 

 

 

 

♦Typical argon shielding gas flow rates are 11 to 35 cfh (cubic feet per hour).

Figures listed are a guide and are a composite of recommendations from American Welding Society (AWS) and electrode manufacturers.

8-2. Preparing Tungsten Electrode For DC Electrode Negative (DCEN) Welding Or AC Welding With Inverter Machines

Y Grinding the tungsten electrode produces dust and flying sparks which can cause injury and start fires. Use local exhaust (forced ventilation) at the grinder or wear an approved respirator. Read MSDS for safety infor- mation. Consider using tungsten containing ceria, lanthana, or yttria instead of thoria. Grinding dust from thoriated electrodes contains low-level radioactive material. Properly dispose of grinder dust in an environ- mentally safe way. Wear proper face, hand, and body protection. Keep flammables away.

Radial Grinding

Causes Wandering Arc

Wrong Tungsten Preparation

2-1/2 Times

Electrode Diameter

2

3

1

4

Ideal Tungsten Preparation − Stable Arc

1 Grinding Wheel

Grind end of tungsten on fine grit, hard abrasive wheel before welding. Do not use wheel for other jobs or tungsten can become contaminated causing lower weld quality.

2 Tungsten Electrode

A 2% ceriated tungsten is recommended.

3 Flat

Diameter of this flat determines amperage capacity.

4 Straight Ground

Grind lengthwise, not radial.

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Miller Electric Maxstar 200 STR manual Amperage Range Gas Type Polarity, Up to
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Maxstar 200 STR specifications

The Miller Electric Maxstar 200 STR is a versatile and compact welding power source designed for a range of applications, making it an ideal choice for both professional welders and hobbyists. Known for its reliability and exceptional performance, the Maxstar 200 STR is capable of delivering high-quality results in various welding processes, including Stick (SMAW) and TIG (GTAW) welding.

One of the standout features of the Maxstar 200 STR is its inverter technology, which allows for efficient energy use and a lightweight, portable design. Weighing in at just 51 pounds, it is easy to transport, making it perfect for fieldwork or remote projects. The unit operates on both 120V and 240V input power, providing versatility for different environments and applications. This adaptability ensures that welders can work effectively in various settings, whether in a shop or on a construction site.

Another significant characteristic of the Maxstar 200 STR is its precise arc control. The machine offers adjustable AC frequency, allowing users to fine-tune the arc characteristics for different materials and thicknesses. This level of control is particularly beneficial when working with aluminum, as it helps reduce heat input and minimize warping. The Maxstar also features a pulsing function, which can enhance the weld pool control and improve penetration, making it easier to achieve clean and consistent welds.

The Maxstar 200 STR boasts a robust duty cycle of 60% at 200A, ensuring that it can handle demanding jobs without overheating. Additionally, the unit is equipped with an advanced cooling system, which helps maintain optimal performance during extended use. Safety features, including overload protection and an enclosed design that reduces the risk of contamination, further enhance the machine's reliability.

Moreover, the Maxstar 200 STR supports a range of accessories, including a remote foot control, which allows for added flexibility during TIG welding operations. This feature is particularly useful for precise control over the welding current, enabling welders to make adjustments on the fly without having to stop and manually change settings.

In summary, the Miller Electric Maxstar 200 STR stands out in the welding industry for its combination of portability, advanced technology, and high performance. With its inverter design, precise arc control, and robust duty cycle, it is an ideal solution for professionals seeking efficiency and quality in their welding projects, whether they are working on industrial applications or artistic endeavors.
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