Operation; Description; Selecting Ac Or Dc Welding Output - Forney 235 Manuel D'utilisation

Operation

Description

ARC (SMAW - Shielded Metal-Arc Welding) welding metals are bonded by heating them with an
electric arc created between the electrode and the workpiece. There are two parts to electrodes used for
SMAW welding:
1) The inner core is a metal rod or wire that should be similar in composition to the base metal.
2) The outer coat-ing is called flux. There are various types of flux and each coating is used for
a particular welding situation.
When the metal is molten, it can be contaminated by elements in the air. Because this contamination
could weaken the weld, the flux coating creates a protective barrier called slag that protects the molten
metal from contaminants.
When current (amperage) flows through the circuit to the electrode, an arc is formed between the end
of the electrode and the workpiece. The arc melts the electrode and the workpiece. The melted metal
of the electrode flows into the molten crater and forms a bond with the workpiece. There are five basic
choices you must make that affect your weld quality:
1. Electrode selection
2. Current setting
3. Weld angle
4. Arc length
5. Travel speed
ONLY EXPERIENCED PERSONNEL SHOULD USE THE POWER SOURCES.

Selecting AC or DC Welding Output

The use of the proper type of welding current is determined by the type of repair that needs to be made.
Alternating current (AC) welding is performed when the welding cables are connected to the AC
electrode and ground jacks. This type of welding current is ideal for heavy plate steel in flat position
welding. Most AC welding operations will be general purpose work on mild steel utilizing AWS rated
6011 and 7018 type electrodes.
Direct current DC welding is performed when the welding cables are connected to the DC+ (Positive)
and DC-(Negative) output receptacles. The 235 AC/DC offers you two DC welding options, straight
or reverse polarity. To weld with straight polarity place the electrode cable plugged into the receptacle
market DC negative and the ground cable or work cable plugged into the receptacle marked DC
positive.
STRAIGHT POLARITY DC welding is ideal for:
• Cutting steel
• Hardfacing work
• Build up work for heavy deposits
REVERSE POLARITY DC welding is ideal for:
• Overhead welding
• Vertical welding
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