Paw Welding Technology Plasma Process Introduction

Plasma welding vs. manual welding

Plasma automatic welding system composition：

1. System components：

2. Automatic welding torch

Plasma+TIG Double welding torch technology

plasma welding power + TIG welding power

Plasma generator

Plasma welding torch (optional wire filling)

TIG torch with shield gas dragging cover

3. Other accessor

What are the characteristics of plasma welding?

High arc compression: The plasma arc, passing through the tiny channels of a water-cooled copper nozzle, undergoes mechanical, thermal, and electromagnetic compression to form a columnar arc with extremely high energy density.

Strong penetration ability (keyhole effect): Under appropriate parameters, the plasma arc can penetrate the workpiece to form a "keyhole," achieving single-sided welding with double-sided forming, and a neat back side.

Good arc stiffness: The arc is straight, highly directional, and not easily deflected, making it insensitive to assembly gaps.

Higher welding speed: Much faster than TIG welding, especially for medium-thick plates requiring single-pass penetration.

Weldable thickness range: From foil (0.1mm) to thick plates (over 12mm, single-pass penetration; multi-layer welding can achieve even thicker thicknesses).

What are the advantages of plasma welding?

Strong penetration:It has strong penetration, bellow 12mm plate welding need not make edge beveling, reducing the preparation time greatly and the amount of wire filling before Welding.

Concentrated highly plasma arc energy:The plasma arc energy is concentrated highly, the thermal effected area is smaller during welding and less deformation after plate welding.

Fast welding speed:Plasma welding is faster than Manual TIG welding and raised by 4-5 times working efficiency.

Single-sided welding & two-sided forming:The rigidity of arc column is strong and using small hole effect can achieve stable performance of single-side welding and two-sided forming, the height, width and narrowness of internal and external welding seams are uniform and beautiful look, which reduces the workload of post-welding seams treatment.

Good welding quality:Good welding quality and suitable for a lot of welding materials.

Long usage life:The electrode is designed in the nozzle of plasma torch, not easy to be burned down and contaminated, long life for electrode usage.

Good controllability：The plasma arc has good controllability and adjustability on welding.

Automatic welding：Plasma welding is automatic mode and easy to be operated, suitable for repeated mass production.

What are the disadvantages of plasma welding?

High equipment cost: It requires a dedicated plasma power supply, welding torch (including tungsten electrode and compressed nozzle), and cooling system (water cooling), making it 2-5 times more expensive than TIG welding machines.

Short nozzle consumable life: The orifice of the compressed nozzle is easily contaminated by the tungsten electrode or burned by the arc, requiring frequent replacement.

Complex operation and adjustment: The parameter window is narrow (current, plasma gas flow rate, welding speed, nozzle height, etc.). Improper settings can easily lead to uncontrolled orifice welding, undercut on the back side, or incomplete penetration.

Unsuitable for thin plate pinhole welding: For plates thinner than 1mm, the pinhole effect is difficult to stabilize, and penetration-type plasma welding (similar to TIG) is usually used instead.

High requirements for gas source:Rare metals require high-purity argon, while others require a hydrogen-argon mixture, and the plasma gas and shielding gas need to be adjusted independently.

Recommendations for PAW Welding

Thickness Range: Optimal thickness for through-hole (pinhole) welding: Stainless steel, titanium alloys 3~12mm (single-sided welding, double-sided forming, no beveling).

Example: 4mm stainless steel, one-time penetration, uniform back side.

Thick plate applications: >10mm, beveling possible, multi-layer welding.

Recommended materials:

Optimal materials: Stainless steel (304, 316, duplex steel), titanium and titanium alloys, nickel-based alloys (Hastelloy, Inconel), copper alloys (especially thick plates), carbon steel, aluminum.

Joint types:

Fillet welds: Rarely used due to the straight plasma arc, making fillet weld control difficult; usually replaced by MIG or manual welding.

Circular/Longitudinal welds: Suitable for both, especially with automatic plasma welding and rotating fixtures, for circumferential welds in pipes and cylinders.

Typical application example: Longitudinal weld in pressure vessel cylinders: 8mm stainless steel, no beveling, through-hole plasma welding, one-time forming, back side reinforcement ≤1mm.