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Weldability

Weldability. Spot weldability. Lesson Objectives When you finish this lesson you will understand: Concept of Spot Weldability Electrode arrangements. Learning Activities View Slides; Read Notes, Listen to lecture Do on-line workbook.

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Weldability

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  1. Weldability

  2. Spot weldability • Lesson Objectives • When you finish this lesson you will understand: • Concept of Spot Weldability • Electrode arrangements • Learning Activities • View Slides; • Read Notes, • Listen to lecture • Do on-line workbook Keywords: Current Level, Current Range, Lobe Curve, Electrode Life, Peel Test, Nugget Size, Button Size, Interfacial Failure, Shunting Effect, Multiple Direct Electrodes, Series Electrodes, Electrode Tooling

  3. Process Characteristics as a Measure of Weldability • Current Level • Current Range & Weldability Lobe • Process Deterioration • Characterization of the loss in weld size at constant welding conditions • Characterization of the variation in process requirements for maintaining welds of an adequate quality Peel Test Used As Measure

  4. Button Size as a Measure of Weld Quality Button Diameter

  5. Modes of Failure in Spot Welds Full Button Irregular Button Interfacial Failure

  6. Process Characteristics as a Measure of Weldability • Current Level • Current Range & Weldability Lobe • Process Deterioration • Characterization of the loss in weld size at constant welding conditions • Characterization of the variation in process requirements for maintaining welds of an adequate quality Peel Test Used As Measure

  7. Nugget Diameter vs. Weld Current Expulsion Acceptable Nuggets Nugget Diameter Minimum Nugget Diameter Small Nuggets Weld Current Nominal Current

  8. Process Characteristics as a Measure of Weldability • Current Level • Current Range & Weldability Lobe • Process Deterioration • Characterization of the loss in weld size at constant welding conditions • Characterization of the variation in process requirements for maintaining welds of an adequate quality Peel Test Used As Measure

  9. Current Range & Weldability Lobe Expulsion Acceptable Nuggets Nugget Diameter Minimum Nugget Diameter Time A Small Nuggets Weld Current Lobe Curve Time A Weld Time Smaller “Brittle” Nuggets Expulsion Level Acceptable Nuggets Weld Current

  10. Questions

  11. Process Characteristics as a Measure of Weldability • Current Level • Current Range & Weldability Lobe • Process Deterioration • Characterization of the loss in weld size at constant welding conditions • Characterization of the variation in process requirements for maintaining welds of an adequate quality Peel Test Used As Measure

  12. Process Deterioration Minimum Acceptable Diameter Weld Diameter Number of Welds

  13. Shunting Effect IB IA B A Itotal = IA + IB IARA = IBRB IB/Itotal = 1 - RB/(RA + RB) [Reference: Resistance Welding Manual, p.1-7, RWMA]

  14. Multiple Direct Electrodes Series Electrode

  15. Tooling for Multiple Welding Welding Pressure Adjustment Screw Stud and Jam Nuts Equalizing Bar Compression Spring Split and Clamped to Electrode Flexible Conductors Flexible Conductors Slip-Fit Slip-Fit Workpiece Lower Electrode (a) (b) [Reference: Resistance Welding Manual, p.17-8, RWMA]

  16. Questions

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