Lesson 1Choosing TIG vs MIG for each joint: criteria for posts-to-baseplate, handrail joints, and infill barsCompare TIG and MIG for typical aluminum joints like posts to baseplates, handrails, and infill bars. Discuss access, appearance, deposition rate, and skill level to guide process selection and parameter setup.
Process comparison: deposition and controlPosts-to-baseplate joint process choiceHandrail and infill bar joint examplesAccess, position, and appearance factorsCost, productivity, and rework trade-offsLesson 2Common aluminum welding defects: porosity, lack of fusion, hot cracking — causes and preventive actionsIdentify common aluminum weld defects such as porosity, lack of fusion, and hot cracking. Link each defect to causes like contamination, poor fit-up, or heat input, and outline inspection methods and corrective actions.
Porosity causes, detection, and preventionLack of fusion from low heat or techniqueHot cracking and solidification controlUndercut and overlap on fillet weldsVisual and NDT checks for aluminum weldsLesson 3Welding sequences and techniques to minimize distortion: tack strategy, stitch welding, alternating sidesShow how welding sequence, tack placement, and bead pattern reduce distortion in aluminum. Cover stitch welding, backstep techniques, alternating sides, and presetting parts to counter expected shrinkage.
Tack weld spacing and size for restraintStitch and skip welding on long jointsAlternating sides to balance shrinkageBackstep technique on thin platePresetting and cambering parts before weldLesson 4Joint assembly and clamping fixtures: minimizing gaps, use of angle fixtures and backingExplain how joint assembly, fit-up, and clamping fixtures affect distortion and weld quality. Cover minimizing gaps, using angle fixtures, backing bars, and adjustable jigs to hold alignment during multi-pass aluminum welding.
Fit-up tolerances and gap controlAngle fixtures for square and miter jointsUse of backing bars and backing stripsAdjustable jigs for repetitive assembliesPreventing movement during tack and weldLesson 5Current types and polarity: AC vs DCEN vs DCEP and when to use eachExplain AC, DCEN, and DCEP for aluminum welding, linking polarity to cleaning action, penetration, arc stability, and electrode heating. Cover typical TIG and MIG setups, machine settings, and how to choose polarity for different joint types.
AC balance and cleaning action on aluminum oxideDCEN for specialized aluminum applicationsDCEP effects on tungsten heating and cleaningPolarity selection for TIG vs MIG processesMachine setup checks for correct polarityLesson 6Pulse welding considerations: benefits for heat input and control, when to applyCover pulse welding principles for aluminum, including peak and background current, frequency, and duty cycle. Explain benefits for heat input control, out-of-position work, thin sections, and how to select pulse programs or manual settings.
Pulse parameters: peak, background, frequencyBenefits on thin aluminum and gap bridgingUsing pulse for out-of-position weldsSelecting factory pulse programs on power sourcesManual tuning of pulse for specific jointsLesson 7Shielding gas selection and flow rates for aluminum weldingDescribe shielding gas options for aluminum TIG and MIG, focusing on argon, helium mixes, and flow rate selection. Address nozzle size, gas coverage, draft protection, and troubleshooting porosity or sooting from poor shielding.
Pure argon for most aluminum TIG and MIGArgon–helium mixes for thick sectionsTypical flow rates by process and nozzleGas lens, cup size, and stick-out effectsDraft shielding and leak troubleshootingLesson 8Interpass cleaning and oxide removal during weldingExplain why interpass cleaning is critical on aluminum, focusing on oxide removal, hydrocarbon contamination, and moisture. Compare stainless brushes, scraping, and light grinding, and define when and how often to clean between passes.
Aluminum oxide properties and weld impactDedicated stainless steel wire brushingSolvent cleaning and degreasing stepsLight grinding and scraping without gougingCleaning frequency between weld passesLesson 9Typical parameter ranges: amperage, travel speed, electrode size, wire diameter examplesProvide typical starting ranges for amperage, travel speed, electrode size, and wire diameter in aluminum TIG and MIG. Emphasize adjusting parameters for thickness, joint type, and position while avoiding common setup errors.
Amperage ranges by material thicknessTravel speed targets for TIG and MIGTungsten diameter and tip preparationWire diameter selection for spray transferParameter adjustment for position changesLesson 10Heat sink and cooling strategies: chill bars, temporary clamps, controlled cooling pausesDetail how heat sinks, chill bars, and clamping reduce distortion and burn-through in aluminum. Cover backing bars, copper shoes, cooling pauses, and water-cooled fixtures, with guidance on when to allow controlled heat buildup.
Chill bar materials and contact requirementsTemporary clamps to control fit-up and warpBacking bars and copper shoes for root supportPlanned cooling pauses between weld passesWater-cooled fixtures and safety concerns
