308A Welding and Soldering for Sheet Metal 2

Question 1

What is 'burn-through' and how is it prevented when welding sheet metal?

Accepted Answer

Melting completely through thin material, prevented by using lower heat settings, faster travel speed, and proper technique

Answer

A type of flame cutting

Answer

A technique for removing paint

Answer

A method of preheating the metal

Question 2

What is the purpose of 'tacking' before welding a sheet metal joint?

Accepted Answer

To hold the pieces in alignment with small spot welds before completing the full weld

Answer

To test the welding machine settings

Answer

To clean the metal surface

Answer

To preheat the joint area

Question 3

What type of solder is used for potable water applications on copper sheet metal?

Accepted Answer

Lead-free solder (95/5 tin-antimony or tin-silver)

Answer

50/50 tin-lead solder

Answer

Acid core solder

Answer

Any available solder

Question 4

What is the proper technique for spot welding sheet metal?

Accepted Answer

Clamp overlapping sheets between copper electrodes and apply pressure with brief electrical current to fuse the layers

Answer

Hold the trigger continuously while moving along the joint

Answer

Heat the metal with a torch and press together

Answer

Use adhesive between the layers and clamp

Question 5

What is 'heat distortion' in sheet metal welding and how is it minimized?

Accepted Answer

Warping and buckling caused by uneven thermal expansion, minimized by stitch welding, clamping, and backstep technique

Answer

Discolouration of the metal near the weld

Answer

The metal becoming harder near the weld

Answer

Smoke generated during welding

Question 6

What is the recommended wire diameter for MIG welding 22-gauge sheet metal?

Accepted Answer

0.023 or 0.030 inch

Answer

0.045 inch

Answer

0.052 inch

Answer

1/8 inch