RobCarpent(at)aol.com wrote:
> In a message dated 3/15/99 5:26:37 AM Pacific Standard Time,
> tebomr(at)cadvision.com writes:
>
> << Porosity is also often a problem with aluminum welding, especially if it
> was done with mig rather than tig welding. >>
>
> What is "mig" and "tig" ?
>
> Rob Carpenter
Rob:
These terms are weldors jargon, and MIG stands for "Metallic Inert Gas" welding
and involves using a machine which feeds
continuous filler wire into the weld area where the arc is shielded by an inert
gas mixture (also more recently known as GMAW).
TIG stands for "Tungsten Inert Gas" welding (also GTAW), and involves using an
air or water cooled non-consumable tungsten electrode which provides the
welding heat and is shielded by an inert gas mixture, while filler rod is fed
in by the operator.
The term "heli-arc" isn't really specific enough to be useful to a weldor since
all it refers to is the presence of helium in the shielding gas in either
process (helium is used in welding copper, nickel-alloy and other reactive
metals, as well as aluminum and is also mixed with CO2 and argon for
high-strength steel).
The TIG process will usually produce a superior weld on aluminum in the hands
of a skilled operator, while the MIG process is faster, cheaper and requires
less skill (also much cheaper machine). For welding a cylnder head, the TIG
process would be the way to go because of better heat control (the arc can be
controlled in mid-weld by a foot-pedal) and more precise welding ( it happens
more slowly and voids and porosity are easier to detect).
Hope this helps -ask if it doesn't!
Ron Tebo
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