Low AMP Plasma Welding Check List for Contaminated Electrode, Dirty Weld Nozzles and Plasma Torch Care.

Where We Stand Now

  1. A dark blue or black tungsten (Figure B) is a sign of moisture or oxygen getting into the plasma gas line (also called the pilot gas line). If the gas is good quality and the gas lines are leak free the tungsten should remain a gray color (Figure A) not dark blue or black. Moisture and oxygen in the gas lines deteriorate the tungsten electrode and thus the number of arc starts that the tungsten electrode can produce is reduced. This cuts down on the number of arc starts in production and decreases production.
  2. Any leaks in the gas lines or fittings can allow air to be sucked into the gas system which adds oxygen and moisture to the welding gases being used. Levels of oxygen and water should be less than 5ppm. The most important gas in plasma welding is the pilot gas, also called plasma gas, is always argon gas. The grade of argon being used should be at least 99.998% pure argon. In plasma welding if the gas is not pure it will contaminate the tungsten electrode and turn the tungsten electrode a dark blue and black color. If the problem is very severe the discoloration will run all the way to the point of the tungsten electrode and the nozzles on the torch will clog up.

  3. To check for gas leaks one needs to install a bottle of gas on the pilot gas line and it is recommended that the gas bottle is used with a dual stage regulator with a stainless steel diaphragm. Next take a nozzle for the torch and solder the orifice of the nozzle closed. Clean the nozzle after soldering with acetone or alcohol and install a small o’ring that will make a seal when the nozzle is screwed into the torch and hand tightened Also make sure that where the nozzle seats against the torch body is clean and free of dirt. If the nozzle does not seat well against the torch body a gas leak can occur. Turn the pilot gas flowmeter up to its highest flow and turn off the argon gas bottle. This will trap gas in between the tip of the torch nozzle and the argon gas bottle. Take a reading on the high pressure gas gauge of the gas regulator. Wait 15 to 30 minutes. If the gas system is leak free the gauge reading will stay the same as when the gas bottle was turned off. If the gauge pressure drops then there is a gas leak in the system. The leak could be caused by a hole in the gas hoses or defective fittings and gaskets.

  4. If the system has a leak you must then go through and check fittings to make sure they are tight and make sure that gaskets are sealing. You can also pinch the plastic hose where the torch connects and trap gas from where the hose is pinched back to the regulator and see if still leaks thus working your back through the gas system.

  5. Check for cracks in the torch body. If the torch has a back cap check the o’ring on the cap and check the cap for holes or cracks.

  6. After it has been determined that the gas system is leak free the system needs to be purged. By purging the gas lines it will clean all of the moisture and oxygen out of the lines so that you will only have good clean gas in the system. Turn the pilot gas flow up to its highest flow rate and let the gas run through the lines for at least 30 minutes to and hour. Next start a pilot arc and let it run at normal pilot arc gas settings (0.4 to 0.6 liters per minute) for 10 minutes. Turn off the pilot arc and check to see if the color of the tungsten electrode is gray. If it is gray your gas system is clean. If the color is black and blue then the system needs to purge longer to make sure it is clean.

  7. If your welding system is shut down over night air with oxygen and moisture will get up inside the plasma torch. Before starting to weld on the next day you need to again purge the gas lines approximately 5 to 10 minutes before starting to weld. You may want to turn the pilot gas down to a very low flow such as 0.1 liters per minute and let the gas run all night to keep the gas line clean. It will be such a low flow that it will not be of any economic importance.

  8. When the pilot arc is turned off let the gas continue to flow for at least 10 to 15 seconds before turning off main power. The gas flow will keep the tungsten electrode from oxidizing until it cools down.

  9. Whenever thinking about electrode life, electrode contamination, ease of arc starting and arc stability you should not forget that the exchange of ions takes place within the plasma column in both directions which is from the electrode to the work piece and from the work piece to the electrode. If impurities such as lead, sulfur, aluminum, magnesium, copper, zinc, brass, oil, grease or any other dirty elements are on or in the material being welded they will contaminate the tungsten electrode and nozzle. You then cannot count on a maximum number of welds before replacing the tungsten electrode and weld nozzle.

  10. Clean the nozzle orifice with acetone or alcohol and a Q-tip. A round wooden toothpick can be used to clean the orifice of the nozzle. Weld nozzles trap contamination during welding and will need to be cleaned every time the tungsten is re-ground.

  11. The pilot arc should be bright white with a light blue tint color. If the color changes to orange or purple that is a sign of contamination. Also the pilot arc will draw back into the nozzle, which is a sign that the tungsten electrode has deteriorated.

  12. WARNING: It is extremely important that when tightening the nozzle onto the torch head that you do not over tighten the nozzle and strip the threads. Copper is a very soft material, which makes it easier to over tighten the nozzle. Tighten the nozzle until it barely makes intimate contact with the end of the torch head. It is recommended that pliers be used to tighten the nozzle but be careful not to grab the torch head with the pliers. Also be careful not to cross thread the nozzle. If the nozzle is cross threaded it will damage the threads inside the torch head. Do not get dirt, grease or oil inside the torch head or on the nozzle threads, which will damage the threads in the torch head. If the torch head is damaged by the pliers it can cause a gas leak between the nozzle and torch head and the nozzle will not seat properly against the water cooled part of the torch head. If the threads are stripped and the torch head is damaged the torch will have to be replaced. Periodically clean the inside of the torch and thread where the nozzle seat with alcohol of acetone. Make sure that the technician that handle the torch and installs nozzles hands are clean. Dirt, oil, grease and grit is not acceptable on any of the torch parts. The plasma welding torch is an expensive device and should handled with great care.

  13. The type of hose material that the pilot gas and shield gas are passed through is very important. All plastics can have moisture and oxygen that diffused through the walls of the hose material. When welding sensitive materials such as titanium the welding system may need to plumbed with stainless steel gas lines.

Selecting Gas Hose For High Purity Plasma Welding

All gases, such as oxygen, moisture, carbon dioxide, and nitrogen, can diffuse through walls of just about all hoses and plastics. Permeation is absent only in all metal all welded pipes. All gases, such as oxygen, moisture, carbon dioxide, and nitrogen, can diffuse through walls of just about all hoses and plastics. Permeation is absent only in all metal all welded pipes.

Permeation is Primarily Dependent Upon:

1. Exposed Surface Area: The longer the hose or the bigger the hose OD, the greater the permeation.

2. Length of Diffusion Path: The longer the path to diffuse, the less the permeation. Thick walled hoses are preferable.

3. Material of Construction: Most important criteria.

4. Nature of Containment: Except for Teflon and polypropylene, most plastics allow a much bigger degree of moisture permeation than oxygen permeation.

5. Temperature & Humidity: The higher the humidity, the greater the moisture permeation. Also, the moisture permeation rate is Higher at higher temperatures but at the same relative humidity. E.g. Moisture permeation at 95° F is approximately double than at 75° F

Look at our Plasma Welding Lathe and give us a call.

Laser Welding for Medical, Dental MFG., Mold Repair; Low Heat Distortion

Advantages of Laser Welding:
• Ability to Join Dissimilar Materials
• Low Heat Input & Low Thermal Distortion
• Filler Metal Welding for Positive Welding
• Faster Weld Rates
• Does Not Need to be Performed In a Vacuum
• Welds Magnetic Materials

Highlights At a Glance:
• AutoFocus System
• Motor movements in X/Y/Z & R
• Auto Teach Mode
• Low Oscillation Due to High
• Quality Rail System

HTS Nd:YAG, Pulsed

Process Welding Systems has enjoyed an excellent reputation for over 15 years with its product line of welding equipment for Plasma and TIG welding. With a mission of providing our customers the best technology available PWS is now offering Laser Welding. The recent advancements in Laser technology has made laser welding a very viable manufacturing process that is a natural extension of our micro welding expertise. When high quality welds are required our weld lab can evaluate your application with laser, plasma or TIG.

Process Welding Systems, Inc. has partnered with O.R. Laser Technologies, Inc. of Elk Grove Village, IL to offer a line of N:YG lasers. In addition to purchasing a 160 watt laser for our lab, PWS offers 120, 160, and 200 watt versions of the HTS laser welder. PWS will provide full sales, service and support for units sold by PWS.

LRS Nd:YAG, Pulsed

This laser leaves nothing to be desired when it comes to working on small to medium sized molds, we offer an extensive range of accessories for all of your laser welding needs. A unique feature are the two Z-axes that come standard. The processing table has a load capacity of 550lbs.

Whether you wish to apply common metal alloys found in tool and mold construction, or aluminum, copper or titanium, the laser capacities in the LRS series are optimally designed for welding. Units range from 50 – 160 Watts.

We also have the right solutions for automated laser welding jobs. CNC control, which is available as an option, and the autofocus system keeps the lasers focal point constant for laser welding for small batches or mass production.

The Difference Between Micro- Plasma and YAG: Laser Welding For Small Parts

YAG: Laser Welding

An acronym for yttrium- aluminum-garnet, the YAG laser produces short-pulsed, high- energy light beams to weld metals. This laser may also be called a neodymium-YAG or ND -YAG laser. A laser type using an infra red wavelength of 1064 nanometers. The laser material is neodymium. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates.

Laser beam welding has high power density resulting in small heat- affected zones and high heating and cool- ing rates. The spot size of the laser can vary between 0.2 mm and 13 mm, though only smaller sizes are used for welding. The depth of penetration is proportional to the amount of power supplied, but is also dependent on the location of the focal point: penetration is maximized when the

focal point is slightly below the surface of the workpiece. A continuous or pulsed laser beam may be used de- pending upon the application. Milliseconds long pulses are used to weld thin materials such as razor blades while continuous laser systems are employed for deep welds. LBW is a versatile process, capable of welding carbon steels, HSLA steels, stainless steel, aluminum, and titanium.

Micro-Plasma Welding Process

Plasma arc welding (PAW) is an arc weld- ing process similar to gas tungsten arc weld- ing (GTAW). The electric arc is formed be- tween an electrode (which is usually but not always made of sintered tungsten) and the

work piece. The key difference from GTAW is that in PAW, by position- ing the electrode within the body of the torch, the plasma arc can be sepa- rated from the shielding gas envelope. The plasma is then forced through a fine-bore cop-

per nozzle which constricts the arc and the plasma exits at the orifice at high velocities (approaching the speed of sound) and a temperature approaching 20,000 °C. Plasma arc welding is an advancement over GTAW.

The Advantages of Laser Welding

  •   Precise Energy Input
  •   Minimum Heat Effected Zone
  •   The Weld is Cool to Touch Seconds After Welding
  •   Welds Can be Sited in Close Proximity toSensitive Components or Structures
  •   Non-Contact Welding
  •   Precise Control of Laser Beam Pulsing Profile
  •   No Contamination From Tungsten Particles
  •   No Heat Discoloration
  •   Welds Magnetic Materials
  •   Low Heat Distortion
  •   No Need for Elaborate Heat Sinks
  •   High Travel Speeds
  •   Highly Reproducible Welds
  •   Advantages of Laser Welding in Tool & Die Repairs


    The Advantages of Plasma Welding

    •   Thin Wire Deposition Using Microscope for Positioning
    •   Ability to Weld in Deep Holes and Cavities
  •   Protected electrode, offers long times before electrode maintenance (usually one 8 Hr Shift)
  •   Low amperage welding capability (as low as 0.05 amp)
  •   Arc consistency and gentle arc starting produce consistent welds, time after time
  •   Stable arc starting and low amperage weld- ing
  •   Minimal high frequency noise issues, HF only in pilot arc start, Pilot Arc Used to Transfer Main Arc
  •   Arc energy density reaches 3 times that of GTAW. Higher weld speeds possible
  •   Weld times as short as 10 msecs (.01 secs
  •   Energy density reduces heat affected zone, improves weld quality
  •   Voltage of Arc Remains Constant WhenLength of arc Changes
  •   Diameter of arc chosen via nozzle orifice
  •   Lower Cost Than Laser

The Cost Differences Between Laser and

For laser Welding Systems the Prices Vary According to the Power Needed. For Thin Materials Usually Low Power YAG Lasers are Sufficient. Low Power YAG Lasers Range in Size from 55 Watts to Several Hundred Watts. Class 1 Lasers come with a Safety Enclosure Around Them. Class Four Lasers are Open. YAG Low Power Lasers Range in Price from $35K to $110K. Higher Wattage Lasers in the Kilo Watt Range Can Cost Several Hundred Thousand Dollars.

Micro-Plasma Welding Systems are Categorized by Welding Current Output. Most Micro-Plasma Welders On the Market have Outputs Be- tween 0.5 to 150 amps. Micro-Plasma Applications use a Welding Current Between 0.5 to 30 amps. In some Cases However Higher Welding Current is Needed. Depending on What is Needed for the Application the Prices of Micro-Plasma Welding Systems can Vary Be- tween $10K for a Manual System, to $17K for a Programmable System.


Special points of interest:

  •   Short Definition of YAG: Laser and Plasma
  •   Process Advantages
  •   Cost Differences

Plasma Welding Summary

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.

The plasma process is equally suited to manual and automatic applications. It has been used in a variety of operations ranging from high volume welding of strip metal, to precision welding of surgical instruments, to automatic repair of jet engine blades, to the manual welding of kitchen equipment for the food and dairy industry.

How Plasma Welding Works:

A plasma is a gas which is heated to an extremely high temperature and ionized so that it becomes electrically conductive. The plasma arc welding process uses this plasma to transfer an electric arc to a work piece. The metal to be welded is melted by the intense heat of the arc and fuses together.

The system requires a power supply and welding torch. In the torch an electrode is located within a torch nozzle having a small opening at the tip. A pilot arc is initiated between the torch electrode and nozzle tip. Gas is fed through the nozzle where the pilot arc heats the gas to the plasma temperature range and ionizes it. The gas emerges from the nozzle in the form of a jet, hotter than any chemical flame or conventional electric arc. The main welding arc transfers to the work piece through this column of plasma gas.

Plasma gases are normally argon. The torch also uses a secondary gas, argon, argon/hydrogen or helium which assists in shielding the molten weld puddle thus minimizing oxidation of the weld.

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

Plasma Welding Features & Benefits:

F: Protected electrode

B: Protected electrode allows for less electrode contamination. This is especially advantageous in welding .materials that out gas when welded and contaminate the unprotected GTAW electrode.

F: Length of arc benefit due to arc shape and even heat distribution

B: Arc stand off distance is not as critical as in GTAW. Gives good weld consistency. No AVC needed in 99% of distribution applications, sometimes even with wirefeed.

F: Arc transfer is gentle and and consistent

B: Provides for welding of thin sheet, fine wires, miniature components where the harsh GTAW arc start would damage the part to be welded.

F: Stable arc in welding

B: Reduces arc wander. Arc welds where it is aimed. Allows and arc starting tooling in close proximity to weld joint for optimum heat sinking.

F: Minimal high frequency noise in welding

B: Minimal high frequency noise once pilot arc started, thus plasma can be used with NC controls. Another benefit lies in welding applications involving hermetic sealing of electronic components where the GTAW arc start would cause electrical disturbances possibly damaging the electronic internals of the component to be welded.

F: Arc energy density reaches 3 times that of TIG

B: Causes less weld distortion and smaller welds. Gives high welding speeds

F: Weld times as short as .005 seconds

B: Extremely short and accurate weld times possible for spot seconds welding of fine wires, accurate weld times combined with precision motion devices provide for repeatable weld start/stop positions.

F: Equipment options offer up to 10,000 Hz

B: Offers a wide range of pulsing options for varied, pulsing applications.

F: Low amperage art welding (as low as 0.05 amp)

B: Allows welding of miniature components or good control in downsloping to a weld edge.

F: Arc diameter chosen via nozzle orifice

B: This feature assists in predicting the weld bead size.

Plasma Welding Features, Benefits & Applications

Features & Benefits:

P Protected electrode, offers long times before electrode maintenance (usually one 8 Hr Shift)

L Low amperage welding capability (as low as 0.05 amp)

A Arc consistency and gentle arc starting produce consistent welds, time after time

S Stable arc in arc starting and low amperage welding

M Minimal high frequency noise issues, HF only in pilot arc start, not for each weld

A Arc energy density reaches 3 times that of GTAW. Higher weld speeds possible

W Weld times as short as 5 msecs (.005 secs)

E Energy density reduces heat affected zone, improves weld quality

L Length of arc benefit due to arc shape and even heat distribution

D Diameter of arc chosen via nozzle orifice

Metals that plasma can weld include stainless, heat resistant and other steels, titanium, Inconel, Kovar, zircalloy, tantalum, copper, brass, gold and silver.


The benefits of the plasma process offers two prime benefits: Increased welding speed and improved weld quality. Plasma is excellent for welding wires, tubes, strips, sheets, and all miniature, medium and large components requiring precision welding. In many applications, many of the unique advantages of plasma combine to benefit the welding process.

Wire 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.

Strip Metal Welding: The plasma process provides the ability to consistently transfer the arc to the workpiece 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.

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

Precision Instruments: Many instruments require welds of great accuracy. Plasma welding, with its control and precision, provides the ability to make these critical welds.

Other Plasma Welding Applications

Surgical Instruments, Needles, Wires, Light Bulb Filaments, Thermocouples, Probes, Pressure and Electrical Sensors, Bellows, Seals, Cans, Enclosures, Microswitches, Valves, Electronic Components, Motors, Batteries, Miniature Tube to Fitting/Flange, Food and Dairy Equipment, Tube Mill Applications, Tool Die & Mold Repair.

Comparison of GTAW & Plasma Welding Energy Input

Test Parameters: Manual welding, no clamping device, Cr/Ni steel, 0.102″ thickness; all values determined with measuring instruments.

GTAW: 125 Amps 12 Volts 10.24 I.P.M.
Plasma: 75 Amps 18 Volts 13.38 I.P.M.
Heat Input: V x A x 60

Speed in cm/min

GTAW: 12 x 125 x 60

Speed in cm/min

= 3.46 KJ
Heat Input: 18 x 75 x 60

34 cm/min

= 2.38 KJ

In addition to the fact that a higher weld speed is possible, the lower heat input brings the following advantages:


  • Less distortion
  • Less stress in welded component
  • Less tempering color with Cr/Ni steels
  • Lower risk of damaging any heat sensitive parts adjacent to the weld joint