Mig Welding Faults; Fault Classification And Description; General Maintenance; Torch Maintenance - CEMONT MS 2000M Betriebs-Wartungs Und Sicherheitsanleitung

GB

9.0 MIG WELDING FAULTS

9.1

FAULT CLASSIFICATION AND DESCRIPTION

MIG welds may be affected by various defects, which are important to identify.
These faults do not differ in form or nature from those encountered during manual
arc welding with coated electrodes. The difference between the two applications
lies rather in the frequency of defects: porosity, for example, is more common in
FAULT
UNEVEN LEVEL
EXCESS THICKNESS
INSUFFICIENT METAL
OXIDISED BEAD
INSUFFICIENT
PENETRATION
OVER PENETRATION
LACK OF FUSION
CHANNELS

10.0 GENERAL MAINTENANCE

DISCONNECT THE POWER SOURCE FROM THE MAINS BEFORE PERFORMING
ANY MAINTENANCE WORK.
Every 5-6 months, remove accumulated dust from the inside of the welding unit
with a jet of dry compressed air (after removing side panels).
BE EXTREMELY CAREFUL TO AVOID BENDING MOVEMENTS, WHICH COULD
DAMAGE AND CHOKE THE TORCH. NEVER MOVE THE POWER SOURCE BY
PULLING THE TORCH.
PERIODICALLY CHECK the condition of the torch, which is the part most sub-
ject to wear.

10.1 TORCH MAINTENANCE:

1. GAS NOZZLE: periodically apply welding spray and clean nozzle interior of
residue.
2. WIRE GUIDE TUBE: check the wire passage of the tube for wear. Replace as
necessary.
MIG WELDING FAULTS
MIG welding, while inclusion of slag is only encountered in welding with coated
electrodes.
The causes and prevention of faults are also quite different.
The following table illustrates the various faults.
APPEARANCE CAUSE AND REMEDY
- Poor preparation.
- Align edges and hold during spot welding.
- No-load voltage or welding speed too low.
- Incorrect torch inclination.
- Wire diameter too large.
- Welding speed too high.
- Welding voltage too low for welding application.
- Weld in the channel if using a long arc.
- Regulate voltage.
- Wire is bent or over-protruding from the wire guide tube.
- Incorrect wire feed speed.
- Incorrect torch inclination.
- Irregular or insufficient distance.
- Wire guide tube worn.
- Wire speed too slow for voltage used or for welding speed.
- Wire speed too high.
- Incorrect torch inclination.
- Excessive distance.
- Distance too short.
- Rough out or grind the weld, then repeat.
- Welding speed too high.
(This fault is easily detected on sight by the welder, and
should be corrected immediately.)

10.2 CONNECTING THE TORCH

Prior to connecting the torch, make sure that the wire sheath (18) is suited to the
diameter of the wire used:
- BLUE Ø 1.5 for wire Ø 0,6- 0.8 mm.
- RED Ø 2.0 for wire Ø 1 - 1.2 mm.
(Wire sheath colour for steel wire).
(GB) 8
19
20
22
21
GB
18