Maintenance - Sealey POWERMIG2750.V2 Instructions Manual

Wire speed must be adjusted according to power output. The higher
the current the faster the wire speed. A gas cup fits over the contact tip
to direct gas flow towards the weld ensuring the arc welding process is
shielded from oxidising air contamination (fig.25). The shielding gas
also assists heating of the weld. The torch is connected to the positive
side of a DC rectifier, and negative clamp is attached to the workpiece.
8.2 Preparation for welding.
IMPORTANT: BEFORE YOU COMMENCE, MAKE SURE THE
MACHINE IS SWITCHED OFF AT THE MAINS. IF WELDING A CAR,
DISCONNECT THE BATTERY OR FIT AN ELECTRONIC CIRCUIT
PROTECTOR. ENSURE YOU READ AND UNDERSTAND THE
SAFETY INSTRUCTIONS IN CHAPTER 1.
8.2.1 Connecting the Earth Lead.
Connect the earth lead as described in section 3.6.
Use the single return earth for steel up to 6mm in thickness, and
the double return earth for steel over 6mm.
To ensure a complete circuit, the earth lead clamp must be securely
attached to the work piece that is to be welded.
a) Best connection is obtained by grinding the point of contact on the
workpiece before connecting clamp to the workpiece.
b) The weld area must also be free of paint, rust, grease, etc.
c) If welding a vehicle, disconnect vehicle battery or fit an "Electronic
Circuit Protector" to battery, (available from your Sealey dealer).
8.2.2 The wire feed rate switch controls the speed of the wire feed. In
principle, the lower the amperage number the slower the wire speed.
8.3 Gas types and their use.
Welding mild steel with CO 2 gas is appropriate for most welding tasks
where spatter and high build up of weld do not pose a problem. To
achieve a spatter free and flat weld however, you must use an
Argon/CO 2 mixture. To weld aluminium use:  Argon gas or Argo-
Helium mixture,  0.8mm Contact Tip,  0.8mm Aluminium Wire,
(MIG/2/KAL08)  Liner (red) Aluminium.
8.4 COMMENCING WELDING.
8.4.1 Before carrying out difficult sections of welding, tests should be
carried out on scrap pieces of metal. These tests should be carried
out to find the best control settings in order to obtain the best welding
possible. As a starting point refer to the welding guide below in
conjunction with the current switch setting charts overleaf. If the arc
melts in drops and tends to go out, the speed of the wire should be
increased or the welding current decreased. If, however, the wire hits
the piece violently and causes material to be projected, the wire
speed should be reduced.
8.4.2 It should be remembered that in order to obtain the best results, each
type of wire is suited to a specific current and wire feed speed.
Therefore, for difficult sections of welding and welding which requires
a great deal of time, wires with different diameters should be tried so
that the most suitable may be chosen.
8.4.3 Turn on and adjust the protective gas using the pressure regulator.
Adjust to a flow rate of 5-7 l/min.
8.4.4 NOTE: At the end of the job, remember to turn off the protective gas.
8.4.5 Switch the welder on and set the welding current by means of
the rotary switch or switches. (Refer to current switch settings overleaf)
8.4.6 Ensure that the earth clamp is in contact with the workpiece.
8.4.7 Press the torch button, keeping the torch at a safe distance from the
workpiece.
8.5 Aluminium Welding.
Argon or an Argon-Helium mixture should be used for shielding. The
wire used must have the same characteristics as the material to be
welded. Always use an alloy wire (i.e. aluminium/silicium); DO NOT
use pure aluminium wire. A problem you may experience when
aluminium MIG welding is in pulling the wire for the whole length of
the torch, as aluminium has poor mechanical characteristics. The
smaller the diameter of wire the more difficult the wire feed may be.
To overcome this problem do the following.
- Use contact tip suitable for aluminium.
- Replace the wire puller rollers with aluminium compatible rollers.
- Replace the steel guide hose for wire feed with a Teflon guide hose.
- For information contact your local Sealey dealer .
8.6 SPOT WELDING (fig.26)
fig.25
8.6.1 This model has the capabilty to spot weld two overlapping metal
sheets and is equipped with an adjustable timer which allows ideal
spot welding time to be set and therefore the creation of spot-welds
which have the same characteristics. In order to use the machine for
spot welding, it should be set-up as follows:
8.6.2 Replace the nozzle of the torch with the nozzle required for spot
welding. The castelations on the cup keep it the correct distance from
the weld pool and allow the shielding gas to escape.The nozzle is
also used to push the two pieces being welded together.
8.6.3 Set the rotary current adjustment switch / switches to the highest
setting. (See current switch setting charts overleaf.)
Set the wire feed speed at almost maximum speed.
Turn ON the Timer control and set the spot welding time according to
the thickness of the metal sheets.
8.6.4 To carry out the spot welding; rest the nozzle of the torch on the
surface of the first metal sheet, then press the torch button to start
welding: the wire will melt the first sheet, pass through this sheet
and into the second, making a molten wedge between the two metal
sheets.
8.6.5 The torch button should be pressed until the timer interrupts the
welding. This system allows spot-welding to be carried out which
would not normally be possible with conventional spot welders, since
metal sheets can be joined which do not allow access to the rear side
of the workpiece.
This system also makes the operator's work much easier thanks to the
extremely light-weight torch in comparison to conventional spot welding
equipment.
The application limits of this system depend on the thickness of
the first metal sheet; the second sheet may be extremely thick.
8.7 Rivet Welding. (Fig 27).
This process allows the re-structuring/re-shaping of dented or
misshaped metal sheets, without the need to hammer the sheet from
behind. This is useful when repairing inaccessible sections of vehicle
bodywork. Replace the torch nozzle with a rivet nozzle. This nozzle
has a side inlet tube for housing the rivet.
Turn the rotary current adjustment switch to position 3.
8.7.1 Adjust the wire feed speed according to the current and the diameter
of the wire used as if a welding operation was to be carried out.
Turn ON the Timer control and set the spot welding time for 1 to 1.5
seconds.
Welding will take place at the point where the head of the rivet is
located and will join the rivet to the metal. The rivet may now be used
as an anchor point in order to re-shape using appropriate appliances.

9. MAINTENANCE

 WARNING! Ensure the unit is disconnected from the mains
power supply before performing any maintenance or service.
9.1 Regularly check all welding cables and secondary terminals to ensure
they are in good order and connected correctly, also check during
welding to ensure they are not overheating.
9.2 Check that the gas hose connections are tight and that there are no
gas leaks.
9.3 Wire feed unit.
Check the wire feed unit at regular intervals. The feed roller wire guide
plays an important part in obtaining consistent results. Poor wire
feeding affects welding. Clean the rollers weekly, especially the feed
roller groove, removing all dust deposits from the feeder area.
9.4 Changing Feed Roller / Rollers IMPORTANT: Set up the feed rollers
according to the wire size required for the job in hand. Refer to section 4
for the Powermig2750 and section 5 for Powermigs 3500 & 4500.
Original Language Version
fig.26
POWERMIG2750.V2, POWERMIG3500.V2, POWERMIG4500.V2
fig.27
Issue: 3 - 09/04/10