The plasma welding process was introduced to the welding industry in 1964 as a method of bringing better control to the arc welding process in lower current ranges. Today, plasma retains the original advantages it brought to industry by providing an advanced level of control and accuracy to produce high quality welds in miniature or precision applications and to provide long electrode life for high production requirements. The plasma welding process offers two benefits: Improved weld quality and increased weld output. Plasma welding offers multiple levels of control, arc stability and weld consistency to produce high quality repeatable welds for many different applications.

Although there are many excellent targeted manual applications, than automated welding system is where plasma can realize its maximum potential. It has been used in a variety of operations ranging from high volume welding of micro components, to precision welding of surgical instruments, to automatic repair of jet engine blades to the manual welding for repair of components in the tool, die and mold industry. Key hole welding application allow full penetration of thicker materials with reduction in bead size and heat affected area.

The system requires a power supply and welding torch. In the plasma welding torch a Tungsten electrode is located within a copper nozzle having a small opening at the tip. A pilot arc is initiated between the torch electrode and nozzle tip. This arc is then transferred to the metal to be welded.

By forcing the plasma gas and arc through a constricted orifice, the torch delivers a high concentration of heat to a small area. With high performance welding equipment, the plasma process produces exceptionally high quality welds on a variety of materials.

• Protected electrode, offers long cycle times before electrode maintenance
• Low amperage welding capability (as low as 0.5 amp)
• Arc consistency and gentle arc starting produce consistent welds, time after time
• Instant arc starting and low amperage welding
• No high frequency noise issues,
• Arc density and force is much higher than GTWA. Yielding higher weld speeds
• Weld cycles as short as .1 secs
• The ability to shape the arc for specific weld applications
• Longer stand off distances

Small Part Welding: The plasma process can gently yet consistently start an arc to the tip of wires or other small components and make repeatable welds with very short weld time periods. This is advantageous when welding components such as needles, wires, light bulb filaments, thermocouples, probes and some surgical instruments.

Sealed Components: Medical and electronic components are often hermetically sealed via welding. The plasma process provides the ability to:

1. Reduce the heat input to the part
2. Weld near delicate insulating seals
3. Start the arc without high frequency electrical noise which could be damaging to the electrical internals

Applications include Pressure and Electrical Sensors, Bellows, Seals, Cans, Enclosures, Micro-switches, Valves, Electronic Components, Motors, Batteries, Miniature Tube to Fitting/Flange, Food and Dairy Equipment,

Tool Die & Mold Repair: A whole repair industry has sprung up to assist companies wishing to re-use components with slight nicks and dents from misuse or wear. The ability of modern micro-arc power supplies to gently start a low amperage arc and make repairs has provided users with a unique alternative to conventional repair and heat treatment. Both the Micro-TIG and micro-plasma welding processes are used for tool, die and mold repair. For outside edges the Plasma process offers great arc stability and requires less skill to control the weld puddle. To reach inside corners and crevices the TIG process allows the tungsten welding electrode to be extended in order to improve access.

Strip Metal Welding: The plasma process provides the ability to consistently transfer the arc to the work piece and weld up to the edges of the weld joint. In automatic applications no Arc Distance Control is necessary for long welds and the process requires less maintenance to the torch components. This is especially advantageous in high volume applications where the material outgases or has surface contaminants.

Tube Mill Welding: Tube mills produce tube and pipe by taking a continuous strip of material and roll forming the edges upwards until the edges of the strip meet together at a weld station. At this point the welding process melts and fuses the edges of the tube together and the material exits the weld station as welded tube. The output of the tube mill depends on the arc welding speed and total time spent welding. Each time the mill shuts down and starts up again there is a certain amount of scrap produced. Thus the most important issues to the tube mill user are:

1. Maximum tube mill weld speed obtainable.
2. Arc stability for optimum weld quality and consistency.
3. Maximum number of hours of welding electrode tip life.

Some tube mills employ plasma welding in order to get a combination of increased weld speed, improved.

Most automated plasma systems require integration of a plasma welding power supply with a single purpose automated welding system. Development of these systems can be complex and require fabrications of machine bases, mechanical, pneumatic, hydraulic and controls engineering to create pick and place part movement. Integration of Robotics as well as positioning fixtures can also be needed to maximize the benefits of plasma welding

EWA can evaluate your specific application and provide one stop shopping to produce the correct plasma welding system for your needs.

Welding of extremely small or thin components as well as pinpointing small critical areas for die repair can be accomplished with a Micro TIG welding station. Contact EWA for a demo of this system.