Tweco 190 MIG Thermal Arc Fabricator - Manual (Page 45)

FABRICATOR 190 WELDING MACHINE
Manual No. 0-4838 4-9 OPERATION
4.07 Technical Tips
Reduce Porosity in the Weld Metal
• Weld in still air to ensure gas coverage
• Clean the dirty, oil, paint, oxidization or grease from
the metal to be welded
• Eliminate any gas leaks in the hose
• Make sure the gas cylinder is not empty with a flow
rate of about 25cfh
Electrode Wire Burns Back to the Contact Tip
• Wire feed speed is too low
• MIG gun liner is blocked with dust or metallic dust
• Bent MIG gun liner
• Damage or worn inlet or outlet wire guides in the wire
drive system
Irregular Weld Beard Shape
• Incorrect or worn feed roller size
• Incorrect size or worn contact tip
• Bad work lead contact to work piece
No Strength in the Weld Joint
• Wire feed speed (welding current) is too low
• Incorrect gas for the material being welded
• Joint preparation too narrow or gap too tight
Cracks Develop in the Weld Metal
• Arc voltage is too high
• The weld cooling rate is too fast
• The stresses in the welded metal are too high
• Weld penetration is too narrow and deep
4.08 Spot Welding Operation
Fit an optional spot welding nozzle to the MIG gun for
consistent spot welding operations. Refer to Figure 4-8
and the Spot Welding Nozzles table below. The Fabricator
will operate effectively using .030” (0.8mm) electrode wire
when spot welding. Penetration depth is limited when
using .023”(0.6mm) electrode wire for spot welding. Set
the controls as follows for maximum penetration when
spot welding:
Output Voltage Control Switch to 8
Wirespeed Control to between 5 to 8
Mode Selector Switch to Spot
Adjust the Spot Time control knob for the desired
weld penetration
Voltage Selector Switches and Wirespeed Control
Select higher Voltage Selector switch positions and set
the Wirespeed Control between 354 to 590 ipm (9 to 15
meters/minute) for maximum penetration.
Mode Selector Switch
Set the MODE SELECTOR switch to SPOT.
Spot Time
Adjust the SPOT TIME control shaft for the desired weld
or ‘ON’ time for spot welding.
21-62-FAS
Art # A-07675
Figure 4-8: Spot Welding Nozzle
SPOT WELDING NOZZLES
TYPE MINI & NO. 1 150 AMP
Flat Arc Spot
21-62-FAS 1210-1520
(5/8" Bore)
Inside Corner Arc Spot N/A
Outside Corner Arc Spot N/A
Automotive Stud Nozzle 21-62 SAS
1210-1524