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Multiprocess 175. Operating manual.
Multiprocess 175. Operating manual.
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11.2 MIG/MAG functions
Power Source
Component
Primary cable
Earth cable and clamp
Connectors and lugs
Switches
Fault symptom
No or low welding output
Arc will not initiate
Overheating of connectors and lugs
Erratic or no output control
Cause
Poor or incorrect primary connection, lost
phase
Damaged, loose or undersized cables and
clamps
Loose or poorly crimped connectors
Switches damaged or incorrectly set for the
application
Wire feeder
Component
Gas solenoid valve
Wire feed rolls
Inlet, outlet guides
Torch connector
Wire feed speed control
Wire inch switch
Spindle
Fault symptom
No gas flow or gas flows continuously
Wire slippage, wire deformation
Wire shaving or snarling
Wire restriction, gas leaks, no trigger control
No control over wire feed speed, no amperage
control
Wire live when feeding through cable and torch
before welding
Wire spool drags or overruns
Cause
Gas valve faulty or sticking in open position
Incorrect feed roll size, incorrect tension
adjustment, misalignment
Incorrect wire guide sizes, misalignment
Torch connector not correctly mounted or
secured, incorrect size of internal guide, bent
contact pins
Faulty wire speed feed potentiometer, machine
in overload or trip condition
Faulty wire inch switch, activitation of torch
trigger switch
Spindle brake set too tight or too loose, spool
not properly located on spindle
Welding torch
Component
Type
Liners
Gas distributor
Nozzle
Contact tip
Nozzle insulator
Fault symptom
Welding torch overheats
Erratic wire feed, wire snarls up at outlet guide
Inadequate gas flow, contaminated or porous
weld
Inadequate gas cover, restricted joint
accessibility
Erratic feeding, wire shudder, wire burnback,
unstable arc, spatter
Arcing between contact tip and nozzle and
between nozzle and workpiece
Cause
Welding torch underrated for welding
application
Liner of incorrect type and size for wire in use,
worn or dirty liner, liner too long or too short
Damaged or blocked distributor
Nozzle too large or too small, incorrect length
or shape
Incorrect size of contact tip, incorrect contact
tip to nozzle distance for metal transfer mode,
tip has worn out
No nozzle insulator fitted, spatter build up has
caused parts to short out
Problem
Porosity in weld
deposit
Cracking in welds
Inadequate shielding
Short parts life
Cause
Entrapped impurities, hydrogen, air, nitrogen, water vapour
Defective gas hose or loose connection
Filler material is damp (particularly aluminium)
Filler material is oily or dusty
Alloy impurities in the base metal such as sulphur,
phosphorous, lead and zinc
Excessive travel speed with rapid freezing of weld trapping
gases before they escape
Contaminated shield gas
Hot cracking in heavy sections or welding on metals prone
to hot cracking
Post weld cold cracking due to excessive joint restraint,
rapid cooling or hydrogen embrittlement
Centreline cracks in single pass weld
Underbead cracking from brittle microstructure
Gas flow blockage or leak in hoses or torch
Excessive travel speed exposes molten weld to atmospheric
contamination
Wind or drafts
Excessive electrode stickout
Excessive turbulence in gas stream
Cup shattering or cracking in use
Short collet life
Short torch head life
Solution
Do not weld on wet material. Remove condensation from
line with adequate gas pre-flow time
Check hoses and connections for leaks
Dry filler metal in oven prior to welding
Replace filler metal
Change to a different alloy composition which is weldable.
These impurities can cause a tendency to crack when hot
Lower the travel speed
Replace the shielding gas
Increase weld bead cross-section size. Change weld bead
contour for e.g. concave to flat or convex, check fit-up gap,
reduce welding speed
Preheat prior to welding. Use pure or non-contaminated gas.
Increase the bead size. Prevent craters or notches. Change
the weld joint design
Increase bead size. Decrease root opening. Use preheat.
Prevent craters
Eliminate sources of hydrogen, joint restraint and use
preheat
Locate and eliminate the blockage or leak
Use slower travel speed or carefully increase the flow rate
to a safe level below creating excessive turbulence. Use a
trailing shield cup
Set up screens around the weld area
Reduce electrode stickout. Use a larger size cup
Change to gas safer parts or gas lens parts
Change cup size or type. Change tungsten position
Ordinary style is split and twists or jams. Change to wedge
style
Do not operate beyond rated capacity. Use water cooled
model. Do not bend rigid torches
The phenomenon listed below may happen due to relevant accessories used, welding material, surroundings and power supply.
Issue
Arc starting difficulty. Arc interruption happens easily
The output current fails to reach the set current
The current is unstable during operation:
This situation may relate to the following factors
Gas vent in welds
Solution
Examine whether grounding wire clamp contacts with the workpieces
well. Examine whether each joint has improper contact.
Check connects are tight and cables are not damaged. Ensure correct
electrode size has been selected.
The voltage of electric power network changes; Serious interference
from electric power network or other electric facilities.
Examine whether the gas supply circuit has leakage. Examine whether
there is sundries such as oil, dirt, rust, paint etc. on the surface.
