PAW WELDING - PLASMA WELDING TECHNOLOGY.

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System Components

• Welding Console - Produces the Torch Pilot Arc, supplies the Plasma and Shield Gases, and remote control interface.
• DC Power Supply - Produces the Welding Arc.
• Coolant Recirculator - Closed loop Torch cooling.
• Weld Sequencer - Optional Current Pulser, Sloper , Weld Timer.
• Remote Controls - Remote Pendant.
• Gases - Torch Plasma and Shield Gas Supply.
• Torch - Plasma Welding Torch available in many configurations.

Plasma Welding Features & Advantages:

•  Protected Electrode - Secluded from contamination by atmosphere and base-metal, allows for many hours of non-interrupted service.
•  Controllable Arc - Can use tip orifice size, electrode set-back and gas flow rates as “mini-tuners.”
•  Multi-Gas Capabilities - Allows for operation of various gases for enhanced welding performance.
•  Pilot Arc - Provides “absolute” arc transfer… Every time.

Plasma Welding Modes of Operation - Plasma welding is commonly used in two modes of operation, melt-in fusion welds and keyhole fusion welds.

Melt-in Fusion – Soft TIG like arc. This type weld mode is the most often used with the plasma arc welding process. It is accomplished with a softer, less constricted arc, using lower plasma gas flow rates, a reduced electrode setback, and current levels in the range of approximately 0.5 to 200 amps. This type of weld mode is very similar to that of gas tungsten arc welding with additional advantages in many applications.

Keyhole – Laser like Arc. This type of weld is generally obtained by using a stiff, constricted arc. In the keyhole mode penetration is obtained by the combination of plasma and gas momentum with thermal conduction. With increased plasma gas flow rates and electrode setback, a hole known as the keyhole is pierced through the entire metal thickness at the leading edge of the weld puddle, where the forces of the plasma jet (column) displace the molten metal. As the torch travel progresses at a consistent speed, the molten metal, supported by surface tension, flows behind the keyhole to form the weld bead. Keyhole welding is almost exclusively performed in the automated mode. Typically this technique is used for square butt welds on material thickness from .093 (2.4 mm) to .250 (6.4 mm) requiring 100% penetration in a single pass. Manual keyhole welding is not recommended because of difficulties in maintaining consistent travel speeds, torch position, or filler material addition.

Microplasma Welding (typical current range 0.1 - 15A) Microplasma is used for welding thin sheets [down to 0.004” (0.1 mm) thickness], and wire and mesh sections. The needle-like, stiff arc minimizes arc wander and distortion.

Medium Current Welding in the Melt-in Fusion Mode (typical current range from 15 - 200A) This is an alternative to conventional TIG. The advantages are deeper penetration (from higher plasma gas flow), greater tolerance to surface contamination including coatings (the electrode is within the body of the torch) and better tolerance to variations in electrode to workpiece distance, without significant change in heat input.

Keyhole Welding (typically over 100A) By increasing welding current and plasma gas flow, a very powerful plasma beam is created which can achieve full penetration in a material, as in laser or electron beam welding. During welding, a keyhole is formed which progressively cuts through the metal with the molten weld pool flowing behind to form the weld bead under surface tension forces. This process can be used to weld thicker materials [up to 3/8” (10 mm) of stainless steel in a single pass.