Date:         27 Nov 96 07:49:09 PST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         CARVER_JEFFREY@aphub.aerojetpd.com (Jeff Carver)
Subject:      Welding 101 (long)

Welding 101 -

A little welding terminology education appears to be in order.
Most of this though the AWS (American Welding Society), the leading 
authority in the US on welding.  One thing they have been trying to 
do is to educate people on consistent terminology, due to common
use of brand and outdated names.  The AWS is  VERY tight ****ed 
about getting info out, unless one BUYS their overpriced books.  

Anyway.

Welding: A joining process that produces a unification of materials by 
heating.  Can be done with or without pressure or filler material.  

As a generic term welding includes brazing and soldering.  

As a specific term welding means that the base material
melts along with the filler material.

Brazing: A process of joining materials with a filler material that melts 
above 450degC (840degF), but below the melting point of the base 
material.  

Most common braze filler materials are is brass, bronze, & aluminum.

Soldering: Same as brazing, but with a filler material below 
450degC (840degF), usually using lead or more recently tin based 
filler material.

Raising the temperature of metal causes it to oxidize very rapidly.  
Some form of shielding is necessary to keep the air (oxygen) from
contaminating the weld.  One technique is to use an inert gas in the 
weld area, usually argon, CO2, helium or a mixture, depending on 
particulars of the weld itself.  Using flux is another technique that uses a 
solid, paste or powdered material that melts at a lower temperature and 
physically and chemically protects the weld.  Flux usually hardens after 
cooling off and needs to be chipped, ground, chemically, etc removed.
But usually cheaper that gas shielding.

Since heat leads to oxidization (rust), if at all possible, gain access to the 
backside of welds and clean them up and protect for rusting by paint or 
other coating.

And now on to some welding processes (I won't cover brazing or 
soldering) but could if prodded.

GMAW =  Gas Metal Arc Welding, aka MIG (old term)
Solid metal weld material.  Arc created between the filler metal and the 
work.  Filler metal usually on a coil.  Gas shielding for the welding.  
Usually a point and shoot type of welder.  Well suited for 
thin sections, most popular for body work.  Gas costs can be high.
Easy to use.

FCAW = Flux Cored Arc Welding, a metal tube with flux in the center, 
the metal being the weld material, the electric arc being made between 
the metal tube and the work.  Usually this wire is supplied as a coil.  
Very easy to weld, point and shoot.  Difficult to control for thin metal.  
Cleanup of flux necessary after welding.  Works well in difficult 
orientations and in difficult weather conditions (Flux protects weld, 
as gas would get blown away)

SMAW = Shielded Metal Arc Weld, aka stick welding.  A solid metal rod 
with flux on the outside surface.  Well suited to large welds, weld 
suited to field repairs.  A VERY good welder can do thinner 
materials.   Can actually be done using a car battery (not while running 
though).  Weld rods are relatively short, not on a coil.

GTAW = Gas Tungsten Arc Welding, aka TIG (old term), or Heliarc 
(brand).  Weld arc created between tungsten handpiece (torch) and 
work.  Filler metal added in using other hand.  Gas shielding from torch.  
Can weld VERY thin material (Have seen soda pop cans welded with 
this process).  Slow process, very precise as welder has complete 
control of welding.  Slow learning curve. Filler material usually 
36in long.

> > As a side note, I received a new Harbor Freight today
> > and they have dropped the price on their non-gas using
> > flux core wire MIG welder to $149!!!!!!! PLEASE Honey........

Flux core and MIG are separate and different processes.
Apparently one can get a GMAW machine and use FCAW wire in it 
without the gas shielding. Sounds logical, but recognize the differences.
Thus this post.

BTW, I am not a welder, but work with them everyday, and work(?) as a 
Weld Engineer, sorta, and have access to loads of technical stuff.

As for which rod to use with which base metal, for the particular 
machine and at what settings, ask at you local supplier
they are more up to date than I.  

As for weldment design and determining the process, that's where I 
have some usefulness.

- Jeff
(2) '80 Westi's