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

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

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

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

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

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

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 1.467 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

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

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 30.2. Assume that the melting factor = 0.25. 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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