Resistance & Solid State Welding

Question 1

What is Cold Welding used for?

Answer 1

To join small workpieces made of soft, ductile metals

Question 2

What are the applications of resistance welding?

Answer 2

Sheet metal fabrication

Automotive body assembly

Question 3

What does the shape of the welded joint depend on on Friction Welding?

Answer 3

Rotational speed and axial pressure applied

Question 4

What is the frequency of oscillation for Ultrasonic Welding?

Answer 4

10 kHz - 75 kHz

Question 5

What are the applications of Cold Welding?

Answer 5

Welding wire stock (splicing wire together)

Some electrical connections work in the same way

Question 6

What are the advantages of Friction Welding?

Answer 6

Does not require consumable electrodes, shileding gases or flux

Question 7

In friction welding, what does the size of the weld zone depend on?

Answer 7

The amount of heat generated
The thermal conductivity of the materials
The mechanical properties of the materials at elevated temperatures

Question 8

Describe Diffusion Welding/Bonding

Answer 8

Occurs when surfaces are held in contact under sufficient pressure and time at elevated temperature
The bonding mechanism is atomic diffusion

Question 9

List the steps required for resistance weldng

Answer 9

Pressure applied
Current on
Current off, pressure on
Pressure released, weld nugget produced at a lap joint

Question 10

What does a solid state process mean?

Answer 10

No melting

Question 11

What is important for an efficient operation in Ultrasonic Welding?

Answer 11

Proper coupling between the transducer and the tip

Question 12

What causes plastic deformation at the interface of the two components and what are the effects?

Answer 12

Shearing stresses

Allows good contact
produces a strong solid-state bond
Breaks up oxide films and contaminants

Question 13

What is friction welding also known as?

Answer 13

Stir Welding

Spin Welding

Question 14

What are the advantages of Explosive Welding?

Answer 14

The bond strength is high

Ability to join numerous combinations of dissimilar metals

Question 15

What does Cold Welding produce?

Answer 15

A weak brittle joint e.g. the bonding of aluminium and steel

Best bond is obtained with two similar metals

Question 16

What does atomic diffusion promote under low pressure and elevated temperature?

Answer 16

Void shrinkage

Grain boundary migration to form a metallurgical bond

Question 17

What are the applications of Friction Welding?

Answer 17

Joins wide variety of materials, in particular solid or tubular parts to provide good strength joint

Question 18

Which process is Friction Welding technically a type of?

Answer 18

Forging because of plastic deformation

Question 19

What are the applications of Diffusion Welding/Bonding?

Answer 19

Titanium welding in aerospace industry

Question 20

Describe resistance welding

Answer 20

Heat required for welding is produced by electrical resistance across two components to be joined

Question 21

For Ultrasonic Welding, what is the temperature of the weld zone?

Answer 21

1/3 - 1/2 of the melting points of the metal joined
Neither melting nor fusion takes place
In certain situations the temperature generated can be sufficiently high to cause metallurgical changes in the weld zone

Question 22

What are the advantages of Ultrasonic Welding?

Answer 22

Versatile and reliable

Can be used with a wide variety of metals (dissimilar metallic workpieces, non-metallic workpieces)

Question 23

What are the applications of Explosive Welding?

Answer 23

High strength joints between aluminium, copper and stainless steel
Corrosion resistant claddings on mild steel substrates

Question 24

What are the solid state processes?

Answer 24

Cold Welding
Ultrasonic Welding
Friction Welding
Explosion Welding
Diffusion Welding/Bonding

Question 25

What's the disadvantage of resistance welding?

Answer 25

Complex and expensive equipment

Question 26

What are the advantages of Diffusion Welding/Bonding?

Answer 26

Ability to join dissimilar metals | Furnaces with inert/protective atmospheres can be used to produce high quality joints

Question 27

What is the most common resistance welding method?

Answer 27

Resistance Spot Welding

Question 28

What are the applications of Ultrasonic Welding?

Answer 28

Joining of plastics Joining dissimilar metallic workpieces Joining non-metallic workpieces

Question 29

What is Method Two of Friction Welding?

Answer 29

Workpiece remains stationary Rotating tool forced onto joint area Material plastically deforms and fuses together

Question 30

Outline Explosive Welding

Answer 30

Pressure is applied by detonating a layer of explosive that has been placed over one of the components being joined The bottom sheet of metal is positioned on a rigid base/anvil The top sheet is inclined to it with a small open angle between the surfaces to be joined

Question 31

What does the quality of the bond depend on for Diffusion Welding/Bonding?

Answer 31

Condition of the materials Pressure Temperature & time at temperature

Question 32

Describe the detonation in Explosive Welding

Answer 32

Explosive material is detonated in a progressive fashion beginning where the two surfaces touch A compressive stress wave sweeps across the surface of the plates Surface films are liquefied or scarfed off the materials and are jetted out of the interface The clean metal surfaces are joined together under high contact pressure

Question 33

Describe the process of Ultrasonic Welding

Answer 33

The surfaces of two components are subjected to a static normal force and oscillating shearing (tangential) stresses The shearing stresses are applied by the tip of a transducer

Question 34

Describe the process of Cold Welding

Answer 34

Pressure is applied to the workpiece either through dies or rolls Plastic deformation takes place It is necessary that at least one, but preferably both parts be ductile Prior to welding, the interface is thoroughly cleaned

Question 35

What are the advantages of resistance welding?

Answer 35

Does not require consumable electrodes, shielding gases or flux

Question 36

What's Method One of Friction Welding

Answer 36

One component remains stationary Other is placed in a chuck/collet and is rotated at a constant high speed The two components to be joined are brought into contact under increasing force. Pressure at the interface and the resulting friction produce sufficient heat for a strong joint to form Flashing removed by grinding

Question 37

What are the applications of Ultrasonic Welding?

Answer 37

Lap welding of sheet, foil, and thin wire (automotive and electronics industries) Packaging with foils Seam welding - Welding tip is replaced with rotating disk