1. FUNDAMENTALS OF WELDING
SME Video – Additional Processes
Welding (vts_02)
Welding Technology
Weld Joints
Physics of Welding
Features of a Fusion Welded Joint
In-class Assignment
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

2. Basics of Arc Welding Joining Permanent joint Assembly
Allow for disassembly
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

3. Welding Joining process Heat and/or pressure Filler material
Economical
Accomplished “in the field”
Disadvantages
Labour cost
High energy
Difficult to detect quality defects
Dangerous
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

4. Fusion Welding – Heat Filler metal is added to the molten pool
Autogenous weld - no filler metal is added
Arc welding (AW)
Resistance welding (RW)
Oxyfuel gas welding (OFW)
Manual arc welding operation
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

5. Solid State Welding – Heat & Pressure
Pressure alone or a combination
Temperature is below melting point
No filler metal is added
Diffusion welding (DFW)
Friction welding (FRW)
Ultrasonic welding (USW)
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

6. Principal Applications of Welding
Construction - buildings and bridges
Piping, pressure vessels and boilers
Shipbuilding
Aircraft and aerospace
Automotive
Railroad
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

7. Welding on the Job Welder Second worker, called a fitter
Welding fixtures and positioners
Safety issues
Ultraviolet radiation emitted in arc welding
Viewing window filters out radiation
Ventilation to exhaust fumes from fluxes
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

8. Automation in Welding Hazards of manual welding Increase productivity
Improve quality
Machine welding
Automatic welding
Robotic welding
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

9. The Weld Joint Butt Corner Lap Tee Edge
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

10. Fillet Welds (a) inside single fillet corner joint
(b) outside single fillet corner joint
(c) double fillet lap joint
(d) double fillet tee joint
Common for oxyfuel welding
Requires minimum edge preparation
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

11. Preparation increases cost
Groove Welds
(a) square groove weld, one side
(b) single bevel groove weld
(c) single V‑groove weld
(d) single U‑groove weld
(e) single J‑groove weld
(f) double V‑groove weld for thicker sections
Preparation increases cost
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

12. Other Weld Types Plug weld Slot weld Spot weld Seam weld
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

13. Other Weld Types Flange weld Surfacing weld
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

14. Physics of Welding – Fusion (most common)
Fusion for achieving coalescence
High density heat energy
Faying surfaces
Temperatures cause localized melting
Metal with minimum energy
High heat densities
Too low
Too high
W/mm2 (Btu/sec‑in2)
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

15. Power Densities for Welding Processes
W/mm2
(Btu/sec-in2)
Oxyfuel 10
(6)
Arc 50
(30)
Resistance
1,000
(600)
Laser beam
9,000
(5,000)
Electron beam
10,000
(6,000)
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

16. Power Density PD = power density, W/mm2 (Btu/sec‑in2)
P = power entering surface, W (Btu/sec)
A = surface area, mm2 (in2)
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

17. Typical Fusion Welded Joint
Principal zones in the joint
Typical grain structure
Heat affected zone
HAZ
Below melting point
High enough to cause microstructural changes
Heat treated region
Failures often occur in HAZ
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

18. In-class Example
A heat source can transfer 3500 J/sec to a metal part surface. The heated area is circular, and the heat intensity decreases as the radius increases, as follows: 70% of the heat is concentrated in a circular area that is 3.75 mm in diameter.
Is the resulting power density enough to melt metal?
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

19. SME Video
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

20. In-class Assignment
In a laser beam welding process, what is the quantity of heat per unit time (J/sec) that is transferred to the material if the heat is concentrated in circle with a diameter of 0.2 mm? Assume the power density provided in previous table.
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

21. Additive Manufacturing
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

22. Time Permitting Content
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e