Spot Welding Flashcards
(40 cards)
What is welding?
Welding is a permanent joining process of two mechanical components by providing thermal energy to the joint, sometimes with additional pressure.
Define base metal and filler metal
-Base metal: The metal pieces to be welded.
-Filler metal: Additional metal added to create the joint.
What is the difference between homogeneous and heterogeneous welding?
-Homogeneous: Base metal and filler metal are the same.
-Heterogeneous: Base metal and filler metal are different.
What is autogenous welding?
A welding process where no filler metal is added; the base metals are fused directly (e.g., TIG or laser welding).
How is brazing different from welding?
Brazing does not melt the base metal; it uses a filler metal with a melting point above 450°C to join the parts.
What is fusion welding?
A welding process where the base metal melts to form the joint (e.g., arc welding, laser welding).
Name three types of arc welding processes
SMAW (Shielded Metal Arc Welding), GMAW (Gas Metal Arc Welding), GTAW (Gas Tungsten Arc Welding).
What is a butt joint?
Two metal pieces placed edge-to-edge and welded.
What is a fillet weld?
A weld joining two pieces at an angle, often in a T or L shape.
What is spot welding?
A process where small weld points are created to join sheet metal.
What is continuous seam welding?
A welding process where a thermal energy source moves continuously to create a seam (e.g., roll welding).
What is projection welding?
Welding performed on prepared locations with embossed features to concentrate heat.
What is ultrasonic welding?
A solid-state welding process using high-frequency vibrations to join materials without melting them.
What are the three phases of ultrasonic welding?
Fragmentation of oxides, mechanical mixing/plastic deformation, and atomic diffusion bonding.
What is the role of the horn in USW?
It transfers ultrasonic vibrations to the workpiece.
What materials are commonly joined using USW?
Thin metals (e.g., aluminum, copper) and thermoplastics.
What is the typical frequency range for USW?
20 kHz to 40 kHz.
How is heat generated in USW?
Through friction caused by ultrasonic vibrations under pressure.
What are the advantages of USW?
Fast, clean, no filler material, minimal thermal distortion.
How is weld quality assessed in USW?
Metallographic observation and tensile shear tests.
What happens if welding time is too long in USW?
Excessive shear deformation can damage the weld.
What is the typical thickness range for USW of metals?
0.005 mm to 2 mm.
Why is surface preparation important in USW?
Contaminants (e.g., grease) reduce friction and weld quality.
What is the main bonding mechanism in USW?
Atomic diffusion.
