(Optional liners must be purchased to cover
Snap-on Tools Corporation Kenosha, WI 53141-1410
1
INTRODUCTION
The Snap-On Tools MIG220
is a combination welding power
source, wire feed unit, MIG torch
and accessory package designed to
to meet the requirements of the
light to medium metal fabrication
industries. The unit produces fusion
welds by the Gas Metal Arc Welding
process (GMAW or MIG), on steel
and aluminum up to 3/8" thick
using .023" through .045" steel
wire and .025" through 3/64"
aluminum wire with the optional
MHG5-A.
given wire sizes).
Heavier sections can be easily
welded using slightly different
techniques.
The number of controls on the unit
has been reduced to assist inexpe-
rienced operators to learn MIG
welding. This facilitates rapid set
up for welding various thicknesses
of material requiring various heat
inputs. The HEAT (voltage) control
adjusts the welding voltage and the
WIRE SPEED control adjusts the
speed of the wire feed motor.
THE MIG PROCESS
AS APPLIED TO THE
MIG220
The MIG process uses a bare,
consumable electrode in the form of
spooled wire, which is fed by a
controllable speed feed unit through
the cable and torch to the weld. The
emerging wire and the weld are
shielded by a stream of CO2, Argon,
or a mixture of the two, which
prevents oxidation of the molten
weld puddle. The gas shield enables
high quality welds to be made
without the use of flux, eliminat-
ing the need for slag or flux
removal after the weld is com-
pleted.
POWER SOURCE
WIRE SPOOL
FEED
ROLLS
WORK
MIG
TORCH
+
REVERSE
POLARITY
(STD.)
_
SHIELDING GAS
ELEC-
TRODE
WORK
The consumable electrode wire is
melted
melted and transferred to the weld
hort
s
modes;
arc
three
of
any
weld
by
the
puddle
to
transferred
and
arc transfer, globular
transfer.
arc
spray
transfer, or
The MIG220.
is capable of
performing all modes on steel and
aluminum.
SHORT ARC OR DIP TRANSFER
Short arc transfer occurs at 12 to
22 arc volts (voltage while weld-
ing), depending on wire size. Weld-
ing commences as the arc is struck
and a weld pool is formed. The tip
of the electrode wire dips into the
pool and causes a short circuit.
The short circuit current flow
causes a rapid temperature rise in
the electrode wire and the end of
the wire is melted off. An arc is
immediately formed between the tip
of the wire and the weld pool,
maintaining the electrical circuit
and producing sufficient heat to
keep the weld pool fluid. The
electrode continues to feed and
again dips into the pool.
FIGURE 1. SCHEMATIC OF MIG PROCESS
FIGURE 2. SHORT ARC TRANSFER
