Welding and Soldering Flashcards

Flashcards covering key concepts in welding and soldering processes.

What does MAGS stand for?

Metal, Arc, Gas, Shielded

What do the Abbreviations TAGS mean?

Tungsten, Arc, Gas, Shielded

How can you improve a Single Vee Butt Weld Joint design to solve the distortion problem?

Redesign the joint to a Double Vee Preparation

List Four Functions of the Coating on Arc Welding Electrodes

•Forms a Protective Shielding Gas to surround the weld pool
•Forms a Protective Slag on the Newly Formed Weld
•Makes the use of AC Possible
•Helps to Direct the Arc by melting at a slower rate that the Electrode Filler Metal
•Can control the Hydrogen Content of the Weld Metal
•Can contain Additives such as alloying metals for the joint
•Can add to the volume of weld metal
•Effect Penetration

List Hard Soldering Processes

•Flame Brazing
•Silver Soldering
•Braze Welding

MMA

Manual Metal Arc

OAG

Oxy/Acetylene Gas

What is the Fundamental difference between ‘Fusion Welding Processes’ and ‘Soldering/Brazing Processes’?

Fusion Welding: The metals to be joined and the Filler metal all melt and coalesce to form the weld structure. Soldering/Brazing Processes: only the Filler metal melts and the strength of the joint depends Upon capillary attraction an minor alloying at the metallic interfaces

Under-Cutting

The melting away of the side walls of the joining metals adjacent to the weld bead. This results in a thinning and weakening of the joining

List causes of Undercutting

Excessive welding Current coupled with to fast a speed of travel, uneven electrode Tilt Angle

What causes welded joint failure?

Usually it is the Lack of Penetration

What results in Excessive Penetration?

Too High Current will result in Excessive Penetration.

List causes of Slag inclusions

Too Low a Welding Current, Too High a Welding Current, Undercutting of Root Runs, Speed of Travel too Fast, Electrode Diameter too Large. Dirty and Greasy surfaces

Lack of Fusion

The failure to fuse together some or all of the weld metal with the Parent Joint Metal

What is primarily caused by the Failure of the process to raise the Temperature of the parent to Melting Point?

Failure of the process to raise the Temperature of the parent to Melting Point,

What are the Five Factors that influence the Degree of Distortion in Welded Joints?

Amount of Restraint, Welding Procedure, Weld Joint Design, Part Fit-up, Parent Metal Properties

The Electrode used in TAGS welding is ‘Non-Consumable’. What does this mean

It does not melt and fuse with the parent metals to form any part of the Weld Metal

MAGS Welding

Direct Current Electrode Positive

List three functions of Fluxes as used in soldering of metal Joints

•Dissolves away Metallic Oxide Film from the surfaces of the Joint
•Keeps Air away from the joint
•Improves the flow (wetting out action) of the solder

Give two reasons as to why steel wire is copper coated for use in the MAGS Process

•Copper is a De-Oxidiser and helps to keep harmful Oxides out of the weld metal
•To stop the Filler Wire from corrosion, thereby protecting the wire- feed mechanisms from damage.

What metal is the Electrode used in TAGS made from? Give Two reasons why this is a suitable metal for the Electrode

Tungsten: •Has a very high Melting Temperature (3400˚C) •Excellent Electrical Conductor

What is the practical implication of Constant Potential’ Power source in relation to the Welding Arc?

The length of the Arc is self correcting . If the arc gap is accidently altered then the current will alter to increase or decrease the burn off rate until the original parameters are re-established

Name three heat sources that are used in soft soldering processes

•Gas Torch
•Electric Soldering Iron
•Copper Bit Soldering Iron
•Induction Furnace

What are ‘Low Hydrogen’ Electrodes?

MMA Welding electrodes that have ‘’Basic’’ type flux coatings. They are designed to control (keep to a minimum) the detrimental quantity of Hydrogen in the weld metal

Give two ways in which fittings used on Acetylene gas hoses differ than those on Oxygen gas fittings

•Acetylene Fittings have Left handed Threads, whereas those for Oxygen are right handed. •Acetylene fittings have a distinctive notch marked on them

Why should Copper Piping or fittings not be used on Acetylene gas lines?

Not used because The compounds Copper Acetylides that form are unstable and can detonate spontaneously causing the gas to explode

Why are Inert Gases are particularly suitable shielding gases to the TAGS Process?

These gases will not Chemically combine with less desirable gases they are Inert and hence shield the molten weld metal from the detrimental effects of oxygen, hydrogen and nitrogen that are present in air.

What units are used to measure Shielding gas flow rates?

Litres/Min

Name three modes of metal transfer that are common in the MAGS Process and give a suitable application for each mode.

vDip Transfer (Welding Light-Gauge Metals) vSpray Transfer (Welding Thick Metals in Down-hand Position) vPulsed Transfer (Light gauge metals where corner build-up is desired)

What is the principle function of the Transformer in Electric Arc Welding Equipment?

To transform the Low Current (15A) High Voltage (220- 380V) Mains Source into a suitable Welding Source with High current (100 – 300 A) Low Voltage (50—80V for Open Circuit and 10 – 25V Arc Voltage).

What are the three possible Flame settings for OAG Flames?

•Carburising (reducing)
⚫Oxidising
•Neutral

E 42 3 B 3 2 H5

Electric Arc Welding Electrode Tensile Strength of Weld Metal Impact Strength Type of Coating B = Basic R =Rutile C =Cellulosic Weld Metal Recovery Welding Position Hydrogen Content of the Weld Metal

DCEN

Direct Current Electrode Negative

DCEP

Direct Current Electrode Positive

AC

Alternating Current

Application of DCEN

•Most of the Heat is concentrated at the Work-Piece
•Deep Narrow Penetration
•Relatively Narrow Gauge Electrodes can carry Large Current

Application of DCEP

•Most of the Heat builds up at the Electrode
•Shallow Penetration
•Good Oxide Cleaning Action

AC is always used when welding what?

AC is always used when welding Aluminium with TAGS welding

Tip Preparation

Pointed Direct Current Stainless Steel

Advantages of Braze Welding V Fusion Welding

Dissimilar Metals can be Joined, Less Heat – Less Distortion, Less Heat – Less Effect upon Grain Structure of Parent Metals

What to consider Joint Preparation Design?

Consider Joint Preparation Design (i.e. single or double vee)

Why mix Argon /Helium Mixtures?

Mixes are used to obtain the most favourable conditions of both gases in terms of heat input, weld speeds and weld bead profile.

size of equipment can be greatly reduced using what?

The size of transformer and hence the size of equipment can be greatly reduced using Inverter Technology

Typical Power Source Relationship between Voltage and Current for equipment used in TAGS Welding and MMA Welding processes.

Constant Current Power Source (Drooping Voltage)

List Three safety Hazards associated with Electric Arc Welding

Inhalation of Fumes, Electrical Shock, Burns from hot and molten metal, Skin Damage, Eye Damage

What is the Electrical Principle Spot Welding Electrical Resistance?

Generates heat the melts the metal at localised spots. This coupled with the physical pressure of the electrodes causes fusion to occur

Tinmans Solder

60% Tin --- 40% Lead

The Central Pipe on OAG Cutting Torch

Delivers the Cutting Oxygen to the central orifice of the nozzle

Ignition Temperature (790˚C for Steel)

Is the temperature at which Iron Burns in Oxygen to produce a Fluid Oxide that can be blown through the Thickness of the metal, producing a Cut Edge (kerf)

Plasma

High Energy, High Velocity, High Temperature Ionised Gas, Created by Passing an Electric Arc through a High speed Jet of either Compressed

Plasma Arc Cutting

Cutting profiles in various metal types in light to medium thickness.

Laser Cutting

Mass production of High Precision metal components and the manufacture of parts for processing equipment and bio-medical equipment