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What are the differences between types of tungsten electrodes?

15 July, 19 5:01 pm · Leave a comment · wpdude
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To begin with, they have different colored bands that are used to identify them.  However, there are several other important differences to consider when selecting a tungsten.  Here some of the various types with the respective characteristics:

EWTh-2:  2% thoriated tungsten.  EWTh-2 is color-coded with a red band.  It is known for its durability, ability to withstand high currents, and excellent arc starts.  It is primarily welded using a negative polarity and direct current. It does not have great characteristics when welding with AC.

EWLa-2: 2% lanthanated tungsten.  EWLa-2 is color-coded with a blue band.  It is known for its excellent arc starting ability, excellent current carrying ability, and can withstand many arc cycles.  It can be welded as the negative electrode using direct current or with alternating current.EWP:  Pure tungsten electrode.  EWP is color-coded with a green band.  It has excellent arc stability. It is almost exclusively used with alternating current.  Tungsten emission is more likely with a pure tungsten electrode when compared with other alloyed tungsten electrodes.

EWCe-2:  2% ceriated tungsten.  EWCe-2 is currently color-coded with a gray band, although in the past it was color-coded with an orange band.  It is quite similar to EWLa-2 in that it has excellent current carrying ability, excellent arc starting ability, and can last through many different arc start and arc termination cycles.

Preventing Wire Feed Issues in MIG and Flux-Cored Welding

15 July, 19 4:53 pm · Leave a comment · wpdude
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Welding with a wirefeeder

Welder working with a wirefeeder under a ship in drydock

How do I prevent wire feeding issues when using the MIG welding (GMAW) or flux-cored arc welding (FCAW) process?

Wire feeding issues can be caused by a variety of circumstances.  Some of the most common reasons for wire feeding issues include:

  • Drive roll tension:  The drive rolls that push or pull the wire through the system have a tension that is either too great or too little.  Adjust the spring pressure until tension is appropriate.
  • Drive roll size: The drive rolls may be the wrong size.  For instance, if 1.3 mm drive rolls are being used to move 0.9 mm wire, slipping will most likely occur.
  • Drive roll type:  Some wire require specific kinds of grooves for optimal feeding.  Flux-cored and metal-cored arc welding wires typically require V-groove drive rolls that are knurled.  Aluminum wires require a smooth U-shaped groove.
  • Drive roll condition:  Worn drive rolls will be ineffective at moving wire through the system.
  • Liner size:  If a liner is too small for the wire it will not feed.  If the liner is too big, the wire may have too much freedom to twist inside of it, causing an unpredictable feed.
  • Liner type:  For most wires, steel liners work excellent.  However, some wires, such as aluminum, require a nylon liner to help ensure proper feeding.
  • Liner condition:  A worn liner will be detrimental to wire feeding.  Replace the liner if it is worn or damaged.
  • Contact tip size:  A proper contact tip size should be used.  If the tip is too small, the wire will not feed; if the tip is too large, wire feeding and electrical conductivity may be negatively affected.
  • Wire condition:  Not all wire manufacturers put out the same quality product.  Some wires may have thin and thick spots as well as lubricants that can cause poor wire feeding.

View our selection of semi-automatic wirefeeders and MIG wire feed welders.

Why use pulsed MIG?

15 July, 19 4:45 pm · Leave a comment · wpdude
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When MIG welding was first invented, it used a constant voltage source of electricity for the arc.  While this method is still used today, the invention of pulsed MIG welding has allowed welders to realize several advantages over conventional MIG welding, several are listed below:

  • Pulsed MIG can be used to weld thin materials.  Conventional MIG welding runs at a constant amperage whereas pulsed MIG welding runs a peak and background amperage.  The constant switching between these two amperages enables pulsed MIG welding to put out a lower overall heat input into the material.  This helps prevent blowouts on thin materials.
  • Pulsed MIG has less spatter than conventional MIG welding.  Pulsed MIG welding uses a peak electrical currents to cleanly burn the wire off at a high amperage.  Pulsed MIG welding also employs a lower background welding amperage immediately after the peak electrical current to prevent the interaction of the electrical arc and the wire from becoming unstable.  This ultimately results in a reduced amount of spatter.
  • Pulsed MIG welding is excellent for out of position welding.  At the same voltage and wire feed settings, conventional MIG tends to have a weld puddle that is larger and more fluid than that of pulsed MIG.  Pulsed MIG has more controllable puddle that prevents it from falling out when gravity is a concern during out of position welding. Furthermore, the reduced amount of spatter than can be achieved with pulsed MIG makes it safer for the welder to perform the out of position operation.
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