Joining Technology - 230413

Question 1

Types of joining technologies

Answer 1

Friction fitting (screws, bolts), form fitting (folding), bonded connections (welding, adhesives)

Question 2

Arc welding

Answer 2

MAG, MIG: GMAW. TIG: GTAW
Electric arc starts when the wire (filler metal) and the part (base metal) touch each other. Arc then generates heat which melts the metal electrode and creates a weld pool. Positive in the electrode and negative (clamped) in the base metal.
Applications: vehicle manufacturing, steel construction, metal construction.

Question 3

Advantages of arc welding

Answer 3

Low cost compared with riveting, joins all metals, robotically.

Question 4

Disadvantages of arc welding

Answer 4

Oxygen, water vapor, air must be kept outside, overhead welding needs a special device to hold the melt.

Question 5

Electric supply

Answer 5

The electric source is basically composed of a couple of transformers, in which the ratio between primary and secondary coils is the ratio between primary and secondary voltages.
Step up andd step down transformers. DC current.

Question 6

Wire feed roller

Answer 6

V groove wire feed roller for steel and rounded for aluminum.
Constant wire feed is essential for the stability of the arc.

Question 7

ISO norm for solid wired electrodes

Answer 7

Wire electrodes for gas metal arc welding GMAW: ISO-14341: Yield point, tensile strength and minimum elongation after fracture.

Question 8

Arc gas welding

Answer 8

Active gas MAG, inert gas welding MIG, tungsten TIG.
MAG: CO2. React with the consumable wire electrode and the weld pool
MIG: Inert: Ar, He non ferrous materials.
M2 most common1: 82% Ar and 18% CO2
Less: porosity, crack formations. More: expensive
Effects on: stability of the arc, metal transfer, weld profile, spatter.

Question 9

Welding parameters arc gas welding

Answer 9

Voltage, wire feed speed, amount of gas.
Stable arc is only achieved if there is a specific ratio between the voltage and current / wire feed speed.
Torch: welding speed, contact tube distance, arc is too long: crack. position of torch.

Question 10

Influence of voltage asuming constant wire feed speed

Answer 10

increase voltage: increase arc

Question 11

ct voltage, influence of wire speed

Answer 11

increase speed short arc, decrease speed long arc

Question 12

Safety risks

Answer 12

optical radiation (UV), electric current, spatter, temperature 4000 degrees.
Leather gloves, eye protection: more amperage, more protection. Highly flame resistant clothes.

Question 13

Difference between MAG, and TIG

Answer 13

Tungsten has a very high melting point, non consumable