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

2. WELDING PROCESSES Arc Welding (AW) Resistance Welding (RW)
Oxyfuel Gas Welding (OFW)
Other Fusion Welding Processes
Solid State Welding (SSW)
Weld Quality & Weldability
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

3. Two Categories of Welding Processes
Fusion welding
Melting of base metals
Arc welding
Resistance spot welding
Oxyfuel gas welding
Solid state welding
Heat and/or pressure
No melting of base metals
No filler metal
Friction welding
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

4. Arc Welding Discharge of electric current across a gap
Arc is sustained by an ionized column of gas (plasma)
Electrode contacts work and then separated
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

5. In-class Assignment
A welding heat source is capable of transferring 150 Btu/min to the surface of a metal part. The heated area is approximately circular, and the heat intensity decreases with increasing radius as follows: 50% of the power is transferred within a circle of diameter = 0.1 inch, and 75% is transferred within a concentric circle of diameter = 0.25 in.
What are the power densities in (a) the 0.1-inch diameter inner circle and (b) the 0.25-inch diameter ring that lies around the inner circle? (c) Are these power densities sufficient for melting metal?
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

6. Test 3 Review Discussion
100 multiple choice
2 problems with calculations similar to in-class examples
1 challenge problem with calculations similar to in-class assignments
1 advanced problem based on the “Energy Balance Equation” worth 4% of test
Additive manufacturing problems will not be on the test
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

7. Energy Balance Equation
Um = K(Tm)2
Um = the unit energy for melting
K = constant of 3.33 x 10-6 J/(mm3∙°K2) for Kelvin scale
K = constant of x 10-6 BTU/(in3∙°R2) for Rankine scale
Tm = melting point of metal (absolute scale)
RHw = f1f2RH = UmAwv
f1 = heat transfer efficiency
f2 = melting efficiency
RHw = rate of heat energy delivered to welding operation
RH = rate of input energy generated by power source
Aw = weld cross-sectional area
v = travel velocity of welding operation
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

8. Melting Temperatures Metal Degrees K Degrees R Aluminum alloys 930
1680
Cast iron
1530
2760
Pure copper
1350
2440
Low carbon steel
1760
3160
Medium carbon steel
1700
3060
High carbon steel
1650
2960
Titanium
2070
3730
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

9. Extra Credit – hand in before test 3
The welding power generated in a particular arc welding operation = 3000 W. This is transferred to the work surface with a heat transfer factor = 0.9. The metal to be welded is copper whose melting point is given in Table Assume that the melting factor = A continuous fillet weld is to be made with a cross‑sectional area = 15.0 mm2.
Determine the travel speed in mm/s at which the welding operation can be accomplished.
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

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

11. Manual Arc Welding Arc Time = (time arc is on) / (hours worked)
Also called “arc-on time”
Manual welding arc time = 20%
Machine welding arc time ~ 50%
Consumable electrodes
Consumed during welding process
Source of filler metal in arc welding
Nonconsumable electrodes
Filler metal must be added separately
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

12. Arc Welding
Metals are chemically reactive to oxygen, nitrogen, and hydrogen in air
Mechanical properties degraded
Arc must be shielded from surrounding air
Arc shielding
Argon, helium, CO2 and flux
Direct current (DC) vs. Alternating current (AC)
AC machines less expensive
DC equipment can be used on all metal
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

13. Shielded Metal Arc Welding (SMAW)
Shielded metal arc welding (SMAW) or stick welding
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

14. Shielded Metal Arc Welding (SMAW)
Used for steels, stainless steels, cast irons, and certain nonferrous alloys
(photo courtesy of Hobart Brothers Co.).
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

15. Gas Metal Arc Welding (GMAW)
Argon and helium (inert) for aluminum welding
Active gases such as CO2 for steel welding
Bare electrode wire plus shielding gases eliminate slag on weld bead
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

16. Flux-Cored Arc Welding (FCAW)
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

17. Electrogas Welding (EGW)
Electrogas welding using flux‑cored electrode wire:
(a) front view with molding shoe removed for clarity
(b) side view showing molding shoes on both sides.
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

18. Submerged Arc Welding (SAW)
Steel fabrication of structural shapes (e.g., I‑beams)
Seams for large diameter pipes and pressure vessels
Welded components for heavy machinery
Most steels (except hi C steel)
Not good for nonferrous metals
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

19. Gas Tungsten Arc Welding (GTAW)
A.k.a. Tungsten Inert Gas (TIG) welding
In Europe, called "WIG welding"
Used with or without a filler metal
Applications: aluminum and stainless steel most common
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

20. Plasma Arc Welding (PAW)
Advantages:
Good arc stability
High travel speeds
Excellent weld quality
Disadvantages:
High equipment cost
Larger torch size than other AW
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

21. Stud Arc Welding (SW) (1) Stud is positioned
(2) Stud is pulled away under current to establish arc
(3) Stud is plunged into molten metal
(4) Ceramic ferrule is removed after solidification
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

22. Resistance Welding (RW) and (RSP)
Rocker-arm spot-welding machine
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

23. Resistance Seam Welding (RSEW)
Applications:
Gasoline tanks
Automobile mufflers
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

24. Resistance Projection Welding (RPW)
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Welding of fastener onto a sheet-metal part
Cross-wire welding

25. Other Resistance-Welding Operations
Flash welding (FW)
High-frequency resistance welding
High-frequency induction welding
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

26. Oxyacetylene Welding (OAW)
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

27. Other Fusion-Welding Processes
Electroslag welding (ESW)
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Pressure gas welding

28. Thermit Welding (TW) Joining of railroad rails (1) Thermit ignited
Repair of cracks in large steel castings and forgings
Weld surface is often smooth enough that no finishing is required
(1) Thermit ignited
(2) Crucible tapped, superheated metal flows into mold
(3) Metal solidifies to produce weld joint.
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

29. Solid State Welding (SSW)
Coalescence of part surfaces is achieved by:
Pressure alone, or
Heat and pressure
No filler metal is added
Essential factors for successful SSW
Very clean
Close physical contact
No melting means no heat affected zone
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

30. Roll Welding (ROW)
Cladding stainless steel to mild or low alloy steel for corrosion resistance
Bimetallic strips for measuring temperature
"Sandwich" coins for U.S mint
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

31. Explosion Welding (EXW)
Bond two dissimilar metals
Clad one metal on top of a base metal
Large areas
(1) setup in the parallel configuration
(2) during detonation of the explosive charge
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

32. Friction Welding (FRW)
Applications:
Shafts and tubular parts
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

33. Ultrasonic Welding (USW)
Wire terminations and splicing in electrical and electronics industry
Eliminates need for soldering
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

34. Weld Quality Shrinkage across the width Butt welding two plates
Residual stresses
Warping
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

35. Weld Quality Various forms of welding cracks Incomplete fusion
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

36. Weld Quality
(a) Desired profile for AW to maximize strength and avoid incomplete fusion and lack of penetration
Desired
Underfill
Undercut
Overlap
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

37. Mechanical Tests and Design Considerations
Tension-shear test of arc weldment
Fillet break test
Tension-shear test of spot weld
Peel test for spot weld
Flat position
Overhead
Horizontal
Vertical
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e