Cracking in Welds
Cause Solution
Hot cracking in heavy sections or welding on metals prone
to hot cracking
Increase weld bead cross-section size. Change weld bead contour for e.g. concave to at or
convex, check t-up gap, reduce welding speed
Post weld cold cracking due to excessive joint restraint,
rapid cooling or hydrogen embrittlement
Preheat prior to welding. Use pure or non-contaminated gas. Increase the bead size. Prevent
craters or notches. Change the weld joint design
Centreline cracks in single pass weld Increase bead size. Decrease root opening. Use preheat. Prevent craters
Underbead cracking from brittle microstructure Eliminate sources of hydrogen, joint restraint, and use preheat
Inadequate shielding
Cause Solution
Gas ow blockage or leak in hoses or torch Locate and eliminate the blockage or leak
Excessive travel speed exposes molten weld to
atmospheric contamination
Use slower travel speed or carefully increase the ow rate to a safe level below creating
excessive turbulence. Use a trailing shield cup
Wind or drafts Set up screens around the weld area
Excessive electrode stickout Reduce electrode stickout. Use a larger size cup
Excessive turbulence in gas stream Change to gas safer parts or gas lens parts
Short parts Life
Cause Solution
Cup shattering or cracking in use Change cup size or type. Change tungsten position
Short collet life Ordinary style is split and twists or jams. Change to wedge style
Short torch head life Do not operate beyond rated capacity. Do not bend rigid torches
The phenomenon listed below may happen due to relevant accessories used, welding material, surroundings and power supply.
Please improve surroundings and avoid these problems.
Phenomenon
Cause Solution
Arc starting diculty. Arc interruption happens easily Examine whether grounding wire clamp contacts with the work pieces well.
Examine whether each joint has improper contact.
The output current fails to reach the set current Check connects are tight and cables are not damaged. Ensure correct electrode size has been
selected.
The current is unstable during operation:
This situation may relate to the following factors
The voltage of electric power network changes;
Serious interference from electric power network or other electric facilities.
Gas vent in welds Examine whether the gas supply circuit has leakage.
Examine whether there is sundries such as oil, dirt, rust, paint etc. on the surface.
47BOC Smootharc 180 Multiprocess operating manual
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