Page 202 - CITS - Welder - Trade Theory

WELDER - CITS

Background current - This is set lower than peak cur-rent and is the bottom current the pulse will drop to, but
must be enough to keep the arc alive.

Pulses per second - This is the number of times per second that weld current reaches peak current.
% on Time - This is the pulse peak duration as a percent-age of the total time, which controls how long the peak
current is on for before dropping to the background cur-rent.

The pulse and base current periods are also controllable.
When welding is done with pulsing welding mode the weld is in principle a row of spot welds overlapping to a
larger or smaller extent depending on the welding speed.

Many double-current machines are equipped with a control function which makes it possible to modify the curve
of the alternating current in balance between the positive and the negative semi-periods
Application of pulse welding

Pulse TIG welding is most commonly used to weld thin sections of stainless steel, non-ferrous metals such as
aluminium, magnesium and copper alloys.

Different types of weld joint, plates & pipe. Advantage

of root pass welding of pipe by TIG welding

Objectives : At the end of this lesson you shall be able to
• describe the filler metals types for TIG welding
• explain the filler metal specification for GTAW
• explain the TIG welding helium gas.

Types of welding joints by TIG welding
There are five basic joint designs mentioned below.

1 Butt joint
2 Lap joint
3 corner joint
4 T joint (Fillet joint)
5 Edge joint

The Fig 1 below shows, filler T joint welded in flat position, When the weld axis and weld face are horizontal.

Fig 1

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CITS : C G & M - Welder - Lesson 61-76