Aircraft Welding (Entire Jeppesen Ch 4)

Define Fusion Welding

Blending of compatible molten metals into one part

Define Non-Fusion Welding

Joining of metals by adhesion

What are the 4 main types of welding we talked about?

1. Oxyacetylene Welding

2. Tungsten inert gas (TIG)

3. Shielded metal arc (Stick)

4. Gas Metal Arc (or MIG, Metal Inert Gas)

What are the 3 methods of TIG Welding? When should you use each?

1. Straight Polarity DC - Heavy work, thick steel

2. Reverse Polarity DC - Use with aluminum, because it breaks up the surface oxides

3. AC - a compromise of both, as the current switches directions

5 types of welded joints

1. Butt Joint

2. Edge Joint

3. Lap Joint

4. Corner Joint

5. Tee Joint

Define Tack Weld

A small round weld that temporarily holds the work together

useful to prevent distortion

What are the 6 parts of a weld?

1. Bead

2. Face

3. Root

4. Throat

5. Toe

6. Reinforcement

Define Bead

The metal that is deposited as the weld is made

Define Face

The exposed surface of the weld

Define Root

The depth of the weld

Define Throat

Distance through the center from the root to the face

Define Toe

The edge formed where the face of the weld meets the base metal

Define Reinforcement

The quantity of weld metal added above the surface of the base metal

What typically can cause improperly formed welds?

1. Undercutting the base metal at the toe of the weld

2. Lack of penetration

3. Poor fusion of the weld metal with the base

4. Oxides, slag, or gas pockets in the weld

5. Improper heat

What is the difference between brazing (AKA Soldering) and Braze Welding?

Soldering uses capillary action to draw the molten metal into the joints,

whereas

Braze welding does that, but also deposits molten metal on the surface.

How are dents at a cluster weld fixed?

By welding on a patch plate of the same thickness and material as the longeron that is dented

How can damage to tubing be repaired? (2 methods)

1. Tube splicing with an INNER sleeve reinforcement

2. Tube splicing with an OUTER sleeve reinforcement

What are rosette welds?

Welds placed in holes that are drilled on one layer of a patch, meant to increase strength due to more welded surface area.

What are the defining characteristics of an acetylene hose?

Acetylene hoses are red and have left hand threads

What are the defining characteristics of an oxygen hose?

Oxygen hoses are green and have right hand threads

3 types of torch flames, how you get them, and what they are used for.

Neutral - 50/50 mix of both gases, used for most things.

Carburizing - More acetylene than oxygen, used for welding high carbon steel

Oxidizing - Less acetylene than oxygen, used for brazing

When shutting off a torch, which gas should be turned off first?

The acetylene valve should be closed first