Miller Electric HF-251-2, HF-251D-1 manual Guidelines for TIG Welding Gtaw, Positioning The Torch

8-2. Preparing Tungsten Electrode For Welding

YGrinding 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.

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

Radial Grinding	2-1/2 Times
	Electrode Diameter
Causes Wandering Arc	3
2
	1
	4

Wrong Tungsten Preparation

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.

2Tungsten Electrode

3Flat

Diameter of this flat determines amperage capacity.

4 Straight Ground

Grind lengthwise, not radial.

B. Preparing Tungsten For Conventional AC Welding

1 − 1-1/2 T imes Electrode Diameter

12

1Tungsten Electrode

2Balled End

Ball end of tungsten by applying AC amper- age recommended for a given electrode diameter (see Section 8-1). Let ball on end of the tungsten take its own shape.

SECTION 9 − GUIDELINES FOR TIG WELDING (GTAW)

9-1. Positioning The Torch

		Y Weld current can damage electronic parts in vehicles. Discon-
			nect both battery cables before welding on a vehicle. Place work
			clamp as close to the weld as possible.
	3	. For additional information, see your distributor for a handbook on the
			Gas Tungsten Arc Welding (GTAW) process.
2		1	Workpiece

1

90°

10−15 °

4

5

6

5 6

1/16 in

3/16 in Bottom View Of Gas Cup

Make sure workpiece is clean before welding.

42 Work Clamp

Place as close to the weld as possible.

3Torch

4Filler Rod (If Applicable)

5Gas Cup

6Tungsten Electrode

Select and prepare tungsten according to Sections 8-1and 8-2.

Guidelines:

The inside diameter of the gas cup should be at least three times the tungsten diameter to provide adequate shielding gas coverage. (For example, if tungsten is 1/16 in diameter, gas cup should be a minimum of 3/16 in diameter.

Tungsten extension is the distance the tungsten extends out gas cup of torch.

The tungsten extension should be no greater than the inside diameter of the gas cup.

Arc length is the distance from the tungsten to the workpiece.

Ref. 161 892

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