I-CAR SWQT common mistakes
I-CAR SWQT · Understand the traps and how to avoid them.
Treating squeeze-type resistance spot welding as interchangeable with GMAW plug welds and substituting one for the other wherever a factory spot weld is shown, without checking the OEM procedure for that specific joint.
Candidates learn that STRSW and plug welding both 'replace a spot weld' and assume the choice is a shop preference rather than a documented OEM requirement tied to steel grade, panel stack-up, and accessibility.
What to do instead
Before welding, locate the OEM repair procedure for the exact panel and steel grade and follow the specified joining method, weld count, and location. If the procedure calls for STRSW, do not substitute GMAW without written OEM authorization; if it calls for plug welds, use the specified hole diameter and count. Record the method used on the repair file.
Setting GMAW voltage and wire feed speed by 'sound and feel' or copying a setting from a different machine, instead of using a written procedure and verifying with a test coupon.
Machines differ in output calibration, cable length, and liner condition, so the same dial numbers produce different arcs. Candidates also confuse voltage with wire feed speed and adjust one to fix a problem caused by the other.
What to do instead
Set parameters from the OEM or machine manufacturer's chart for the wire type, diameter, and gas being used, then run a test coupon on the same gauge and joint type as the repair. Adjust one variable at a time: wire feed speed controls current and penetration, voltage controls arc length and bead profile. Log the final settings.
Selecting shielding gas by what is already on the cart, using 100% CO2 or a rich CO2 blend on advanced high-strength or ultra-high-strength steel where the OEM specifies a specific argon-rich mixture.
CO2 is cheap and gives good penetration on mild steel, so candidates generalize it to all GMAW work without recognizing that gas composition affects heat input, weld chemistry, and the strength of the finished joint in AHSS.
What to do instead
Check the OEM welding procedure for the required gas mixture and flow rate for the specific steel grade. Use the specified blend, set flow with a calibrated flowmeter at the nozzle (typically in the range the procedure states), and verify the regulator is not leaking or the cylinder is not near empty before starting.
Welding ultra-high-strength steel or heat-treated components that the OEM marks as not repairable by welding, such as certain boron-alloyed B-pillars, roof rails, or hot-stamped parts.
Candidates see a crack or bend and default to 'weld it back', not realizing that some UHSS grades lose their engineered properties when heated and that OEMs prohibit welding or straightening on specific parts.
What to do instead
Identify the steel grade from the OEM body repair manual or panel stamping before any heat is applied. If the procedure prohibits welding or heat straightening, replace the part at the specified sectioning location using the approved joining method. Treat any unidentified high-strength part as non-weldable until confirmed.
Ignoring heat-affected zone management: running a continuous bead along a long panel, or welding without checking for adjacent heat-sensitive parts, backing, or corrosion protection.
Continuous beads feel faster and look neater, but concentrated heat input softens or embrittles the HAZ, distorts panels, and can damage nearby modules, wiring, or fuel lines that candidates did not move.
What to do instead
Use the stitch, skip, or backstep sequence the OEM specifies, keep heat input within the procedure's limits, and allow cooling between passes. Protect or remove heat-sensitive components, use heat sinks or backing where called for, and restore corrosion protection on both sides of the weld afterward.
Reading a welding symbol as if the arrow side and other side were interchangeable, or ignoring the tail, supplementary contour, and size/length callouts on the symbol.
Candidates memorize the basic fillet and groove shapes but not the convention that the reference line's top and bottom indicate which side of the joint is welded, so they weld the wrong side or miss a staggered or intermittent pattern.
What to do instead
Read the symbol in order: arrow side versus other side, weld type and size, length and pitch for intermittent welds, contour and finish, then the tail for process or specification notes. Sketch the joint and mark which side is which before welding, and confirm against the OEM diagram that the symbol matches the intended joint.
Judging weld quality only by appearance, accepting a smooth 'pretty' bead without checking penetration, and skipping destructive testing on the test coupon.
A visually acceptable bead can sit on top of the metal with little fusion, especially with low current or a long arc. Candidates are reluctant to destroy a weld they just made and treat destructive testing as optional.
What to do instead
Weld a coupon that matches the repair joint, then perform the destructive test the OEM or standard requires, such as a peel test, chisel test, or bend test, and inspect the fracture face for penetration, fusion, and porosity. Adjust parameters and repeat until the coupon passes before welding the vehicle.
Misdiagnosing common defects: calling porosity 'bad wire', burn-through 'too much heat' without checking gap and backing, or missing lack of fusion hidden under a wide cap.
Defects have overlapping symptoms and candidates reach for the most familiar cause instead of working through the checklist of gas flow, liner condition, contact tip wear, travel angle, joint fit-up, and current.
What to do instead
Use a structured diagnosis: for porosity check gas flow, leaks, wind, dirty base metal, and wire condition; for burn-through check gap, backing, and travel speed; for lack of fusion check current, travel angle, and joint access. Correct one cause at a time and re-test on a coupon before returning to the vehicle.
Overlooking basic shop safety controls: welding near exposed fuel or brake lines, not using fume extraction, wearing the wrong eye protection for the process, or leaving the work area without a fire watch.
Candidates focus on the weld itself and treat safety as common sense, underestimating fume exposure from coatings and the fire risk from sparks traveling into hidden cavities and trim.
What to do instead
Before striking an arc, remove or shield flammable materials, cover fuel and brake lines, set up fume extraction at the arc, wear the correct shade and PPE for the process, and maintain a fire watch during and after welding. Follow the shop's hot work and vehicle isolation procedures.
Skipping or misapplying the OEM sectioning and joint design requirements: cutting at an arbitrary location, using the wrong backing, or joining dissimilar steel grades with the wrong process.
Candidates cut where the damage ends or where access is easiest, rather than at the OEM-specified sectioning location, and they do not check whether the joint requires a backing plate, insert, or specific weld pattern for that steel combination.
What to do instead
Locate the OEM sectioning diagram for the panel and cut only at the approved location, using the specified joint design, backing, and weld sequence. Confirm the steel grades on both sides of the joint and use only the joining processes the OEM approves for that combination. Document the sectioning point and method in the repair record.