HeroApply
Auto Apply to hundreds of jobs in a few hours
English (US)EspañolItalianoPortuguêsFrançaisDeutsch日本語한국어
Sign up

Aluminum Welder interview questions

An aluminum welder interview is mostly a conversation about what goes wrong and how you fix it. The supervisor already knows the weld test will show your hands. The talk is there to find out whether you understand why aluminum cracks, porosity shows up and thin sheet blows out, so you don't learn it on their parts.

11 questions7 minute read

Part 1

1.Walk me through how you prep an aluminum joint before you strike an arc.

Why they ask

Most aluminum defects start before welding. They want to hear that you treat prep as part of the weld, not a chore.

How to answer

  • Degrease first with acetone or the shop's approved solvent on a clean rag
  • Then use a stainless brush kept only for aluminum, so you don't drag steel or oil into the joint
  • Weld soon after brushing, because the oxide layer comes right back
  • Keep filler rod clean and in its tube, and wipe it if it's been sitting out

2.You're getting porosity all through your bead. What do you check, in order?

Why they ask

Porosity is the most common aluminum problem on the floor. They want a calm, ordered troubleshooter, not someone who starts turning knobs.

How to answer

  • Contamination first: dirty base metal, oily filler, moisture on the part
  • Gas coverage next: flow rate, leaks in the line or torch, drafts from a fan or open door
  • Torch angle and cup size, and whether the tungsten stick-out is too long for the gas lens
  • Change one thing at a time and run a test bead on scrap before going back to the part

3.How do you set AC balance and frequency, and what does each one change?

Why they ask

This separates people who've actually run AC TIG on an inverter from people who've only watched it.

How to answer

  • Balance trades cleaning action against penetration: more cleaning widens the etched zone and heats the tungsten
  • Run just enough cleaning to keep the puddle clear, then push toward penetration
  • Higher frequency narrows and focuses the arc, which helps on fillets and tight corners
  • Mention the machine you've set up, whatever brand it was, so they know it's real
4.How do you keep from blowing through thin sheet?

Why they ask

Thin gauge aluminum is where a lot of production work lives, and burn-through means scrapped parts.

How to answer

  • Tight fit-up so you're not bridging gaps with extra heat
  • Use a foot pedal or pulse to back off heat as the part warms, since aluminum soaks it up then lets go all at once
  • Travel speed steady and a bit quicker than you'd expect
  • Heat sinks or backing bars where the fixture allows, and stitch welding to spread heat
5.What's causing crater cracks at the end of your welds, and how do you stop them?

Why they ask

Crater cracking is a classic aluminum defect and an inspector will catch it. They want to know you understand the stop.

How to answer

  • The crater shrinks as it cools and cracks if it isn't filled
  • Add filler as you taper off, or use the machine's crater fill or downslope
  • Don't just snap the arc off at the end of the joint
  • Grind out and reweld any crack you find instead of welding over it

Part 2

6.How do you choose filler for an aluminum job?

Why they ask

Filler choice affects cracking, strength and color after anodizing. They want someone who checks, not guesses.

How to answer

  • Follow the weld procedure or the print first, because it may already specify the filler
  • Know the common general-purpose filler and the higher-strength magnesium filler your shop stocks and when each is used
  • Consider whether the part will be anodized or painted, since some fillers show a color mismatch
  • Ask the lead or engineer when the base alloy isn't marked
7.A long aluminum frame pulled out of square after welding. What would you do differently next time?

Why they ask

Aluminum expands and moves more than steel. Distortion control is a planning skill, and they want to see you think ahead.

How to answer

  • Tack more often and balance the tacks from side to side
  • Weld in a sequence that alternates sides and backsteps along long seams
  • Use the fixture and clamps, and let the part cool between passes
  • Measure diagonals before final welding so you catch it early
8.Have you run a spool gun or push-pull gun on aluminum? What goes wrong with wire feeding?

Why they ask

Soft aluminum wire tangles and birdnests. Production MIG shops need someone who can keep it feeding without calling maintenance.

How to answer

  • Name the setup you've used and the kind of parts you ran
  • Use U-groove drive rolls and only enough tension to feed
  • Keep the right contact tip for aluminum and replace it when it gets burned or tight
  • Keep the liner clean and the gun cable as straight as you can
9.Read this weld symbol for me.

Why they ask

They need to know you can build from a print without someone standing over you.

How to answer

  • Say which side is the arrow side and which is the other side
  • Name the weld type, size, length and pitch for stitch welds
  • Point out any finish or contour symbol and any note in the tail
  • Say what you'd ask if something on the print looked wrong
10.What safety steps do you take that are specific to aluminum?

Why they ask

Aluminum work has its own hazards, and a shop that gets written up doesn't want to repeat it.

How to answer

  • Fume extraction or a respirator, especially on MIG with heavy fume
  • Keeping aluminum dust away from steel grinding sparks and from the wrong kind of dust collector
  • Watching for bright arc reflection off shiny metal and covering skin
  • Following the shop's fire watch and housekeeping rules

Part 3

11.Tell me about a part you scrapped. What happened?

Why they ask

Everyone who welds aluminum has ruined parts. They want honesty and a lesson, not a claim of perfection.

How to answer

  • Pick a real one and describe it plainly
  • Say what caused it, like rushing prep or not tacking enough
  • Say how you told your lead and what you changed afterward
  • Keep it short and end on the habit you kept

Questions to ask them

Ask at least two. It shows you're picking them too.

  • Which alloys and thicknesses make up most of the work here?
  • Is the aluminum work mostly TIG, pulse MIG, or a mix, and what machines are in the cell?
  • How are parts inspected, and who signs off before they ship?
  • Do you keep aluminum separate from steel in the shop, with its own brushes and grinders?
  • Will I test for a certification here, and does the shop pay for renewals?