W E L D I N G
EXPERT TIPS
ON
TIPS
NOZZLES:
GETTING THE
MOST FROM
YOUR EQUIPMENT
YOU CAN GREATLY
REDUCE DOWNTIME SPENT
CHANGING CONTACT TIPS
AND TROUBLESHOOTING
WELD DEFECTS BY CAREFULLY
CHOOSING MIG GUN
CONSUMABLES AND
CARRYING OUT A
REGULAR INSPECTION
AND MAINTENANCE
SCHEDULE. HERE ARE
SOME POINTERS.
By Andy Monk
I t doesn’t take much to create an arc with
your MIG welding set-up.All you really
need is a power source, some CO2, a MIG gun,
ground cable and a wire electrode. Of course,
that doesn’t mean you’ll end up with a mechani-
cally sound or decent looking weld. Achieving
those results requires a strong skill set, close
attention to detail and the right MIG welding
consumables (among other things, of course).
Often overlooked during the purchasing pro-
cess MIG gun consumables – the contact tip,
nozzle and diffuser – are the decisive variables
in electrical transfer to the wire and shielding gas
to the weld pool. No matter how well tuned the
rest of your welding equipment is to your applica-
tion, without the right consumables in properly
functioning order, your weld quality will suffer.
Obtaining high quality welds and high pro-
ductivity rates requires attention to the type
of consumables you purchase, how they are
34 FABRICATING & METALWORKING MARCH 2010 FANDMMAG.COM
RECESS/ WIRE
AMPERAGE PROCESS NOTES
EXTENSION STICK OUT
1/4-in. Recess >200 amps 1/2 – 3/4-in. Spray, High Current Pulse Metal Cored wire, spray transfer, argon-rich mixed gas
1/8-in. Recess >200 amps 1/2 – 3/4-in. Spray, High Current Pulse Metal Cored wire, spray transfer, argon-rich mixed gas
Flush <200 amps 1/4 – 1/2-in. Short Circuit, Low Current Pulse Low argon concentrations or 100 percent CO2
Maintaining the correct contact tip stick out or recess, as it relates to the end of the nozzle, is crucial to ensuring good weld results. The
amount that a contact tip is recessed or extended past the nozzle determines the wire stick-out and how much heat from the arc the contact
tip absorbs. High current, high heat applications generally require a contact tip recessed up to ¼ in from the end of the nozzle. Lower
amperage applications, or those with narrow joint configuration, might require a flush or extended contact tip
and reduces the inventory footprint and time spent monitoring and
ordering new product.
Equally important is choosing the right consumables for the applica-
tion. For example, using heavy-duty nozzles, with thick-walls as well
as wide nozzle bores, will only add weight and reduce weld pool
visibility in low-amperage, thin-gauge applications. Likewise, using
thin-walled brass nozzles with narrow nozzle openings in heavy-duty
applications could result in inadequate shielding gas coverage, fre-