Tweco 181i Fabricator User Manual download pdf (Page 61)

Fabricator 181i

Manual 0-5191 4-3 BASIC WELDING GUIDE

Distance from the MIG Gun Nozzle to the Work Piece

The electrode wire stick-out from the MIG Gun nozzle should be between 3/8" (10mm) to 3/4" (20.0mm). This

distance may vary depending on the type of joint that is being welded.

Travel Speed

The speed at which the molten pool travels inﬂuences the width of the weld and penetration of the welding run.

MIG Welding Variables

Most of the welding done by all processes is on carbon steel. The items below describe the welding variables in

short-arc welding of 24 ga. (0.6mm) to ¼” (6.4mm) mild sheet or plate. The applied techniques and end results

in the MIG process are controlled by these variables.

Preselected Variables

Preselected variables depend upon the type of material being welded, the thickness of the material, the welding

position, the deposition rate and the mechanical properties. These variables are:

•

Type of electrode wire

• Size of electrode wire

• Type of gas (not applicable to self shielding wires FCAW)

• Gas ﬂow rate (not applicable to self shielding wires FCAW)

Primary Adjustable Variables

These control the process after preselected variables have been found. They control the penetration, bead width,

bead height, arc stability, deposition rate and weld soundness. They are:

•

Arc Voltage

• Welding current (wire feed speed)

• Travel speed

Secondary Adjustable Variables

These variables cause changes in primary adjustable variables which in turn cause the desired change in the bead

formation. They are:

1. Stick-out (distance between the end of the contact tube (tip) and the end of the electrode wire). Maintain

at about 3/8" (10mm) stick-out

2. Wire Feed Speed. Increase in wire feed speed increases weld current, Decrease in wire feed speed decreases

weld current.

Art # A-08997_AD

Gas Nozzle

Electrode Wire

Average Arc Length

Electrode Stick-Out

Tip to

Work Distance

Actual Stick-out

Contact Tip (Tube)

Figure 4-8

3. Nozzle Angle. This refers to the position of the welding MIG Gun in relation to the joint. The transverse

angle is usually one half the included angle between plates forming the joint. The longitudinal angle is

the angle between the centre line of the welding MIG Gun and a line perpendicular to the axis of the weld.

The longitudinal angle is generally called the Nozzle Angle and can be either trailing (pulling) or leading

(pushing). Whether the operator is left handed or right handed has to be considered to realize the effects

of each angle in relation to the direction of travel.

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