50 pages for welders, cutting operators and workshop owners: causes in order of likelihood, the fix for each, starting settings and a checklist. Type what you see, or pick a category.
Reviewed by the Cruxweld technical team, October 2026. Built from Cruxweld machine documentation and recognised industry references. Settings are starting points to confirm on a test piece; acceptance is decided by the code or drawing the job is built to.
Start from what you can see on the weld or the cut, or type it in the box above.
| What you see | Most likely | Read |
|---|---|---|
| Small holes in the bead, or a sponge-like weld | Gas cover lost or dirty metal | Porosity → |
| Groove along the edge of the weld you can feel with a nail | Undercut: too hot, too fast, wrong angle | Undercut → |
| Metal balls stuck all over the plate | Spatter: voltage not matched, dirty plate, CO2 | Spatter → |
| Bead looks good but peels off in a break test | Lack of fusion: too cold, arc on the pool | Lack of fusion → |
| Back of the butt weld shows the original plate edges | Incomplete penetration: no gap or bevel, low current | Incomplete penetration → |
| Bead edge curls over the plate like a wave | Overlap: too much wire, too little heat | Overlap (cold lap) → |
| Hole or sag through the plate | Burn-through: too hot or too slow | Burn-through → |
| Dark pockets inside the weld, slag stuck in the toe | Slag inclusion: interpass cleaning, downhill, low current | Slag inclusion → |
| Crack down the middle of the bead, or next morning in the plate | Hot crack or hydrogen crack | Weld cracks → |
| Star-shaped crack at the end of the weld; pits beside the weld | Crater cracks and arc strikes | Arc strikes and crater cracks → |
| Bead too high and ropey, or flat and hollow, or uneven | Settings: read the bead | Bad bead shape → |
| Arc leans sideways near corners and plate ends | Arc blow | Arc blow → |
| Plate bent, frame twisted after welding | Distortion: heat input and sequence | Distortion → |
| Wire not feeding, stutters, birdnests, burns back to the tip | MIG wire path | MIG / MAG welding problems → |
| Electrode sticks, arc will not start, arc breaks | Stick: current, earth, damp electrodes | ARC / MMA welding problems → |
| HF crackles but no arc; grey or black TIG weld; arc wanders | TIG: tungsten, gas, machine | TIG welding problems → |
| SAW bead porous, undercut, slag sticks; tractor stops; fault code | Submerged arc | Submerged arc welding problems → |
| Carriage bead uneven, wanders off the seam, stops mid-weld | Welding carriage set-up | Welding carriage and automation problems → |
| Spot weld peels, sparks, deep marks, tips stick | Spot welding: current, time, force | Spot welding problems → |
| Aluminium weld porous, cracked, black soot, wire will not feed | Aluminium: oxide, hydrogen, heat | Aluminium welding → |
| Stainless weld rusts, root looks like sugar, heat tint, buckled sheet | Stainless: contamination, oxygen, heat | Stainless steel welding → |
| Plasma cut has heavy dross, bevel, arc will not start, consumables die | Plasma: speed, height, air, consumables | Plasma cutting problems → |
| Gas cut will not start, slag sticks, face gouged, torch pops | Oxy-fuel: nozzle, pressure, speed, safety | Gas (oxy-fuel) cutting problems → |
| CNC parts out of size, torch dives or lifts, pierce fails, bad holes | CNC: kerf, height control, pierce, program | CNC plasma and flame cutting problems → |
| MIG machine: lamp on, no wire, no gas, breaker trips, torch hot | Machine checks: MIG | MIG welding machines → |
| TIG machine: no HF, HF but no arc, O.C. lamp, no argon | Machine checks: TIG | TIG welding machines (DC) → |
| AC/DC TIG: aluminium oxide not removed, tungsten burning | Machine checks: AC/DC TIG | AC/DC TIG machines → |
| ARC inverter: overheat lamp, breaker trips, arc breaks | Machine checks: ARC inverter | ARC inverter machines → |
| Transformer or rectifier: phase lamp off, stiff handle, humming, fuse blows | Machine checks: transformer / rectifier | ARC transformers and rectifiers → |
| Welding generator: engine will not start, stops, no output | Machine checks: generator | Welding generators → |
| Plasma cutter: no pilot arc, no air, cuts then stops, parts burn fast | Machine checks: FINELINE | FINELINE plasma cutters → |
| SAW machine: fault code on the display, tractor will not start | Machine checks: CSW SAW | CSW submerged arc machines → |
| Spot welder: pedal down no weld, weld lamp on no weld, tips hot | Machine checks: spot welders | Spot welders → |
| Carriage: control lamp off, stops, wanders, oscillator dead | Machine checks: carriages | Welding carriages → |
| Gas cutting machine: motor runs no travel, speed uneven, torch leak | Machine checks: gas cutters | Gas cutting machines → |
| CNC: torch will not find the plate, arc but no motion, collision alarm | Machine checks: CNC | CNC cutting machines → |
| Flux-cored: worm tracks on the bead, spatter and porosity, slag under the bead | FCAW: polarity, stick-out, gas or none | Flux-cored (FCAW) welding problems → |
| Weld nut turns off, some projections not welded, spatter in the threads | Projection welding: force, current, time, die | Projection welding problems → |
| CD stud breaks off, fusion on one side, marks on the back of thin sheet | CD stud: voltage, gun, surface | CD stud welding problems → |
| Drawn-arc stud: collar incomplete or one-sided, fails bend test, through-deck | Drawn-arc: current, time, lift, ferrule | Drawn-arc stud welding problems → |
| Stud welder: will not charge, discharges by itself, charged but no discharge, E01 / E04 | Machine checks: stud welders | Stud welding machines and guns → |
| Pipe cut ends do not meet, circle not closing, template tracking off | Pipe and profile cutting set-up | Pipe and profile cutting problems → |
| Nickel strip not sticking to the cell, sparks, burnt strip, weak peel | Battery tab welding: strip, tips, pressure, current | Battery tab welding → |
| Bandsaw blade breaks at the weld, brittle joint, stepped joint | Blade welding: step, upset, anneal, grind | Bandsaw blade welding → |
| Wire joint breaks on drawing, heavy burr, dry powdery weld | Wire butt welding: current, pressure, spacing, anneal | Wire and rod butt welding → |
| Seam looks continuous but leaks, skipped nuggets, pickup on the wheels | Seam welding: current, times, speed, force | Seam welding → |
| Tube-to-tubesheet weld leaks, pinhole at the stop, bead uneven round the tube | TubeSeal: centring, projection, overlap | Tube-to-tubesheet welding → |
| Dent puller pad comes off, hole in the panel, metal stretched | Dent pulling: bare metal, power, technique | Dent puller spot welder → |
| Jewellery weld black or pitted, electrode sticks, gas lamp flashing | Pulse-arc: argon, tip, power | Jewellery pulse-arc welding → |
| Torch cooler: pump hums or no flow, torch still hot, coolant | Machine checks: water cooler | Welding torch water coolers → |
What the defect looks like, its causes in order of likelihood, the fix for each, and a prevention checklist.
Problems that belong to the process and the machine: wire feeding, arc starting, tungsten, flux, electrodes, carriages.
Aluminium and stainless steel behave differently from mild steel. What changes, and the mistakes that cost the most.
Plasma, oxy-fuel and CNC cutting: dross, bevel, pierce failures, dimensional errors, consumable life.
Battery tab, bandsaw blade, wire and rod butt, seam, tube-to-tubesheet, dent pulling and jewellery welding: process and machine on one page each.
Your Cruxweld machine, its lamps and fault codes, the checks an operator can do outside the cabinet, and the point at which to call us.
Most defects come from the metal surface, the gas, the consumable condition or the settings, not from the welding machine. Work through the causes on each page first. If the machine really is the limit, for example not enough current at the duty cycle thick plate needs, the product finder and the cost calculator help you pick the right one, and the spares page gets you consumables for the one you have.
A photo, your machine model, consumable and plate thickness is enough. Our technical team replies on WhatsApp with the likely causes and the next checks to make.
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