Joining Processes Welding Brazing Soldering 1 Brazing and

Joining Processes: Welding, Brazing, Soldering 1. Brazing and Soldering: Melting of filler rod only • Brazing: higher temperature, ~brass filler, strong • Soldering: lower temp, ~tin-lead filler, weak 2. Welding: Melting of filler rod and base metals 3. Both: Join inexpensive parts to form complex product sales. nordex-online. com

Types of Joints Kalpakjian

Brazing • Steel base metal + Brass filler rod is common en. wikipedia. org • Lower temp than welding: retains heat treatment (if present), minimizes grain growth. • Strong but slow (careful preparation, cleanup) • Furnace brazing is easily automated Kalpakjian www. kirkframeworks. com

Shielded Metal Arc Welding (SMAW): “Stick welding” • Older, simple technology • The electrode is also the filler rod • Only for steel • Strong welds if done properly (but often not) • Very high heat input: good for thick parts, bad for grain growth and distortion Kalpakjian

Gas Metal Arc Welding (GMAW): “MIG” (Metal-Inert-Gas) • ~Complex mechanism but simple to perform and easy to automate • The electrode is also the filler rod, fed continuously from a spool. It melts in the arc. • For steel or aluminum • Low skill level can achieve good weld • Medium heat input: distortion and grain growth are significant Kalpakjian

Gas Metal Arc Welding (GMAW): “MIG” (Metal-Inert-Gas) A fair/typical quality MIG weld (still hot!) www. scenta. co. uk www. mig-welding. co. uk www. difflock. com

Gas Tungsten Arc Welding (GTAW): “TIG” (Tungsten-Inert-Gas) • The electrode is tungsten (not consumed) • The filler rod is separate and fed manually • High skill level required to achieve good weld • Difficult to automate • Low heat input and small weld bead: distortion and grain growth are minimized Kalpakjian

Gas Tungsten Arc Welding (GTAW): “TIG” (Tungsten-Inert-Gas) • Typical good quality TIG welds www. steelmancycles. com www. kosman. net

Resistance Spot Welding (RSW): “Spot Welding” • No filler rod: electrical current is passed through metal under pressure • Low skill level required • Easy to automate • Low heat input and no weld bead: distortion and grain growth are minimized Kalpakjian

Distortion from Welding Processes • Non-uniform shrinkage of weld bead • Difficult to maintain alignments • Solution: Rigid fixtures, pre-compensate for warping, loose tolerances Kalpakjian

Weld bead profile: Convex or Concave? • Solidification of molten bead leads to shrinkage • Shrinkage of a concave bead leads to tension on surface tends to crack • Shrinkage of a convex bead leads to compression on surface does not crack • Generally, slightly convex beads are preferred. Lincoln Electric

Welding Flaws Kalpakjian

Welding Flaws: Incomplete Penetration (not enough heat input) www. mig-welding. co. uk www. ndt-ed. org/Education. Resources

References Kalpakjian: http: //www. nd. edu/~manufact/index 3. htm