Introduction to Materials Joining

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Non Arc Welding Processes Resistance Weld High
Energy Density Friction Welding Brazing
Soldering Plastics Joining
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Non-Arc Welding Processes (Part 1)

• Lesson Objectives
• When you finish this lesson you will understand
• Resistance Weldability and Various Resistance
  Welding Processes
• Oxy-fuel welding and cutting principles
• Solid state welding processes and comparisons
  between them
• Advantages and disadvantages of each process

• Learning Activities
• Read Handbook pp 16-30
• Look Up Keywords
• View Slides
• Read Notes,
• Listen to lecture
• View Video
• Do on-line workbook
• Do Homework

Keywords Resistance Spot Welding, Seam Welding,
Spot Weldability Lobe, Oxy-Acetylene Torch,
Friction Welding, Diffusion Welding, Ultrasonic
Welding, Explosive Welding
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Non-Arc Welding Processes
Introduction

• Resistive heating, chemical reactions, focused
  light and electrons, sound waves, and friction
  can also be used to join materials
• Resistance welding
• Oxy-Fuel Welding
• Friction welding (Solid State)
• Laser and electron beam welding
• Brazing and soldering
• Plastics joining
• Adhesive bonding

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Resistance Welding
Resistance Welding

• The resistance of metal to the localized flow of
  current produces heat
• Process variables
• Current
• Time
• Force
• Spot and seam welding

Spot welding
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electrode
electrode
Spot Weld
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Electrodes
Resistance Welding
Truncated cone Dome Pointed

• Electrode tips wear during service, causing
  nugget size to decrease
• Zinc-coating on steel alloys with copper
  electrodes to form brass
• Copper base materials, divided into classes

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Operating Window - Lobe Curve
Resistance Welding
Constant electrode force
Acceptable nugget size
Time (cycles of current)
Expulsion
Nugget too small
Current (1000s of amperes)
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Roll spot weld
Overlapping seam weld
Continuous seam weld
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Resistance Welding Advantages

• High speed, lt 0.1 seconds in automotive spot
  welds
• Excellent for sheet metal
  applications, lt ¼-inch
• No filler metal

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Process Disadvantages and Limitations
Resistance Welding

• Higher equipment costs than arc welding
• Power line demands
• Nondestructive testing
• Low tensile and fatigue strength
• Not portable
• Electrode wear
• Lap joint requires additional metal

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Videos
Link to the Resistance Welding Videos from the
Video Page on the WE300 Webpage
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Questions?

• Turn to the person sitting next to you and
  discuss (1 min.)
• If the Lobe Curve represents the welding
  parameter combinations which produce good welds,
  why do so many of the automotive spot welds have
  expulsion?

• Turn to the person sitting next to you and
  discuss (1 min.)
• When spot welds are place too close to one
  another, some of the current from the second weld
  shunts thru the first. Why then can overlap seam
  welds work when the welds are so close that they
  overlap?

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Non-Arc Welding Processes
Introduction

• Resistive heating, chemical reactions, focused
  light and electrons, sound waves, and friction
  can also be used to join materials
• Resistance welding
• Oxy-Fuel Welding
• Friction welding (Solid State)
• Laser and electron beam welding
• Brazing and soldering
• Plastics joining
• Adhesive bonding

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( Oxygen from torch)
(Oxygen from Air)
Linnert, Welding Metallurgy, AWS, 1994
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Thermite Welding
Power Fe2O3 2Al gt 2Fe Al2O3 heat
Base Metal
Liquid
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Questions?

• Turn to the person sitting next to you and
  discuss (1 min.)
• The oxy-fuel and that thermit welding are both
  chemical burning reactions. In the first oxygen
  is supplied by oxygen gas, in the thermit
  welding, it is supplied by the iron oxide. Why
  does this aluminum burning in the thermit
  welding work?

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Non-Arc Welding Processes
Introduction

• Resistive heating, chemical reactions, focused
  light and electrons, sound waves, and friction
  can also be used to join materials
• Resistance welding
• Oxy-Fuel Welding
• Friction welding (Solid State)
• Laser and electron beam welding
• Brazing and soldering
• Plastics joining
• Adhesive bonding

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Solid-State Welding

• Processes that produce a weld through the
  application of pressure at a temperature below
  the melting temperature of the base material no
  filler metal is used
• Friction welding
• Diffusion welding
• Ultrasonic welding
• Explosion welding

0.1.1.2.2.T9.95.12
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Friction Welding (FRW)
0.1.1.2.2.T10.95.12
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Friction Welding - Advantages
Friction Welding

• For correct part geometry, friction welding is
  faster than most other processes
• Can join dissimilar materials together
• Copper to steel or aluminum
• Easily automated for high volume production
• Can join plastics

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Limitations of Friction Welding
Friction Welding

• Start-up cost is high
• Parts must be able to rotate about an axis of
  symmetry
• Free machining alloys are difficult to weld
• Non-forgeable materials cannot be friction welded

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Diffusion Welding Working Principles
1st stage deformation and interfacial boundary
formation

• 1st stage
• deformation forming interfacial boundary.
• 2nd stage
• Grain boundary migration and pore elimination.
• 3rd stage
• Volume diffusion and pore elimination.

asperities come into contact.
2nd stage grain boundary migration and pore
elimination
3rd stage volume diffusion pore elimination
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AWS Welding Handbook
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Ultrasonic Welding

• Advantages
• Fast
• Can spot or seam weld
• Limitations
• Equipment complex, many variables
• Only use on small parts
• More on this below for plastics

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Principles of Explosion Welding
Detonator
Explosive

• Welding arrangement consists of three components
  -
• Base component
• Prime component
• Explosive.
• Base component remains stationary, supported by
  anvil.

prime component
Base component
Component arrangement for explosion welding
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Principles of Explosion Welding

• Prime component is placed either parallel or at
  an angle to the base.
• Explosive is distributed over top surface of
  prime component.
• Upon detonation, prime component collides with
  base component to complete welding.

Prime component
Weld
Jet
Base component
Action between components during explosion
welding.
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Linnert, Welding Metallurgy, AWS, 1994
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Questions?

• Turn to the person sitting next to you and
  discuss (1 min.)
• In friction welding, the outer part of the bar
  is moving faster and will therefore have more
  heating than the exact center of the bar. What
  might you do to even out the heating across the
  entire interface?

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Homework
Do Special Project Homework on Solid State Welding