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Physics of Projection Welding

Physics of Projection Welding. Projection Physics. Learning Activities View Slides; Read Notes, Listen to lecture Do on-line workbook. Lesson Objectives When you finish this lesson you will understand: The collapse of the projection during welding

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Physics of Projection Welding

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  1. Physics of Projection Welding

  2. Projection Physics • Learning Activities • View Slides; • Read Notes, • Listen to lecture • Do on-line workbook • Lesson Objectives • When you finish this lesson you will understand: • The collapse of the projection during welding • Factors effecting the projection collapse Keywords Current Concentration, Projection Collapse

  3. Projection Welding of Low Carbon Steel (Two Equal Thicknesses) [Reference: Resistance Welding Manual, p.3-13, RWMA]

  4. Functions of Electrode Force • The electrode force must hold the projection firmly against the mating part during the initial period of “weld time” where the current density is high and the collapse rate is rapid. • The electrode force must cause complete collapse after welding, so the resulting sheet separation is minimized. • The electrode force has a major influence on the degree of porosity in the weld nugget. It must be low enough to give proper projection collapse without metal expulsion and yet high enough to produce comparatively sound welds. • The suitable dynamic force characteristic must prevail without producing excessive initial impact force.

  5. Effect of Weld Time Tensile-Shear Strength (lbs) Nugget Diameter Projection Collapse Weld Time (Cycles) Weld Time (Cycles)

  6. Factors Affecting Heat Balance • Projection Design • Part Thickness • Die Material Backing up the Weld • Metal Conductivity • Heating Speed

  7. Projection Weld Formation Stage 1 Stage 3 Stage 2 Stage 4 [Reference: Resistance Welding Manual, p.3-9, RWMA]

  8. Projection Weld Formation (CONT.) Stage 5 Stage 7 Stage 6 Stage 8 [Reference: Resistance Welding Manual, p.3-9, RWMA]

  9. Link to projection weld video

  10. Recommended Projection Designs T(in.) D(in.) H(in.) L(in.) 0.010-0.014 0.055 0.015 1/8 0.016-0.020 0.067 0.017 5/32 0.025 0.081 0.020 3/16 0.031-0.034 0.094 0.022 7/32 0.044-0.050 0.119 0.028 9/32 0.062-0.070 0.156 0.035 3/8 0.078 0.187 0.041 7/16 0.094 0.218 0.048 1/2 0.109 0.250 0.054 5/8 0.125 0.281 0.060 11/16 0.140 0.312 0.066 3/4 0.156 0.343 0.072 13/16 0.171 0.375 0.078 7/8 0.187 0.406 0.085 15/16 0.203 0.437 0.091 1 0.250 0.531 0.110 1-1/4 T L H D T: Thickness of thinnest outside piece D: Diameter of projection H: Height of projection L: Minimum contacting overlap [Reference: Recommended practice for resistance welding, AWS Document C1.1-66, AWS, 1966]

  11. Effect of Welding Time Stage 1 Stage 5 Stage 2 Stage 6 Stage 3 Stage 7 Stage 4 Stage 8 [Reference: Resistance Welding Manual, p.3-9, RWMA]

  12. Variation in Weld Head Position during Projection Welding 0.062-inch Thick Steel Initial Collapse Final Collapse Current Nugget Expansion Electrode Position Weld Cool 60 Cycle Timing Trace [Reference: A study of projection welding, Welding Journal Research Supplement, 27(12), p.712s-713s, Hess & Childs]

  13. Variation in Weld Force during Projection Welding 0.125-inch Thick Steel 1000 lbs. Weld Cool Time [Reference: A study of projection welding, Welding Journal Research Supplement, 27(12), p.712s-713s, Hess & Childs]

  14. Effect of Welding Current 20,000 30 cycles 45 cycles 60 cycles 15,000 Welding Current, Amps 10,000 [Reference: A study of projection welding, Welding Journal Research Supplement, 27(12), p.712s-713s, Hess & Childs] Projection: D = 0.40” H = 0.027” Electrode Force: 1500 lbs 5,000 0 0.25 0.50 Diameter of Fused Zone, in.

  15. Relations between Weld Current, Weld Time and Weld Strength on 0.040-inch Thick Mild Steel 1500 Shear Weld Strength, lbs 1000 Nominal Tension [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p.15s-23s, Hess & Childs] 500 Projection D = 0.10” H = 0.025” Electrode Force 400 lbs 10 cycles 15 cycles 20cycles 4000 5000 6000 7000 Welding Current, Amps

  16. Effect of Projection Shape 1500 Shear 1000 Weld Strength, lbs Normal Tension 500 [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p.15s-23s, Hess & Childs] Projections Electrode Force DHlbs 0.010” 0.025” 400 0.140” 0.025” 450 4000 5000 6000 7000 Welding Current, Amps

  17. Effect of Electrode Material RWMA Classification Group B, Class 12 0.20 RWMA Classification Group A, Class 3 RWMA Classification Group A, Class 2 Fused Zone Diameter, inches 0.10 Weld Time: 15 cycles 0 4000 5000 6000 7000 Welding Current, Amps [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p.15s-23s, Hess & Childs]

  18. Effect of Weld Spacing on Nugget Development (a) 1-in. Spacing (b) 3/4-in. Spacing (c) 1/2-in. Spacing [Reference: A study of projection welding, Welding Journal Research Supplement, 27(12), p.712s-713s, Hess & Childs]

  19. Additive Effect of Projection Weld Strengths for Multiple Welded Assemblies Projection: D = 0.10” H = 0.025” AISI 1010 AISI 1015 AISI 1020 Weld Current: No. of welds x 6340 Amps Electrode Force: No. of welds x 400 lbs Weld Spacing: 0.75” Weld Time: 15 cycles 4000 Shear 3000 Weld Strength, lbs 2000 [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p.15s-23s, Hess & Childs] 1000 Normal Tension 0 0 1 2 3 4 Number of Welds

  20. Variations in Projection Weld Hardness Thickness: 0.125” Weld Time: 45 cycles 400 1020 300 1015 Hardness, VPN 1010 200 Fused Zone 100 0 0.25 0.50 0.75 1.00 Distance across Weld, inches [Reference: A study of projection welding, Welding Journal Research Supplement, 27(12), p.712s-713s, Hess & Childs]

  21. Effect of Material Hardenability on Weld Strength Projection: D = 0.10” H = 0.025” Electrode Force: 400 lbs 1500 Shear 1000 Weld Strength, lbs Normal Tension 500 [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p.15s-23s, Hess & Childs] AISI 1010 AISI 1015 AISI 1020 Weld Time: 15 cycles 0 4000 5000 6000 7000 Welding Current, Amps

  22. Cold Projection Collapse Annular : 0.110” Diam. Spherical: 0.075” Diam. Spherical: 0.085 Diam. Spherical: 0.065 Diam. 0.020 Projection Height, inches 0.010 0 0 100 200 300 Electrode Force, lbs [Reference: The projection welding of 0.010 and 0.020 inch steel sheet, Welding Journal Research Supplement, 29(9), p.3-13, Nippes & Gerken]

  23. Nugget Development Using Spherical Projections for 0.020-in. Thick Steel 3760 Amps 4950 Amps 4260 Amps 5330 Amps [Reference: The projection welding of 0.010 and 0.020 inch steel sheet, Welding Journal Research Supplement, 29(9), p.3-13, Nippes & Gerken]

  24. Nugget Development Using Annular Projections for 0.020-in. Thick Steel 4740 Amps 5100 Amps 5520 Amps 5940 Amps [Reference: The projection welding of 0.010 and 0.020 inch steel sheet, Welding Journal Research Supplement, 29(9), p.3-13, Nippes & Gerken]

  25. Current Range Characteristics 0.020”-1010 Steel Annular Projection Height: 0.015” Diameter: 0.110” Weld Time: 6 cycles Electrode Force: 225 lbs 0.20 Plug Diameter, inches 0.10 Spherical Projection Height: 0.020” Diameter: 0.075” Weld Time: 6 cycles Electrode Force: 150 lbs 0 2000 3000 4000 5000 6000 Weld Current, Amps [Reference: The projection welding of 0.010 and 0.020 inch steel sheet, Welding Journal Research Supplement, 29(9), p.3-13, Nippes & Gerken]

  26. Strength Characteristics Spherical Projection Height: 0.020” Diameter: 0.075” Electrode Force: 75 lbs Weld Time: 6 cycles Pickled in 50% HCl Shear Strength Normal Tension 0.020”-1010 Steel 200 Load, lbs 100 Annular Projection Height: 0.016” Diameter: 0.077” Electrode Force: 110lbs Shear Strength Normal Tension 0 1000 2000 3000 4000 Welding Current, Amps [Reference: The projection welding of 0.010 and 0.020 inch steel sheet, Welding Journal Research Supplement, 29(9), p.3-13, Nippes & Gerken]

  27. Effect of Weld Force on Strength Characteristics Annular Projection Height: 0.015” Diameter: 0.110” Weld Time: 6 cycles Electrode Force: 110 lbs Electrode Force: 130 lbs Shear 200 Normal Tension Load, lbs 100 0.020”-1010 Steel 0 2000 3000 4000 5000 6000 Welding Current, Amps [Reference: The projection welding of 0.010 and 0.020 inch steel sheet, Welding Journal Research Supplement, 29(9), p.3-13, Nippes & Gerken]

  28. Projection Welding Schedule of Light-Gauge Steels [Reference: Resistance Welding Manual, p.3-13, RWMA]

  29. Additive Effect of Multiple Projection Welds Annular Projection Height: 0.015” Diameter: 0.110” Shear Normal Tension Theoretical 1000 0.020”-1010 Steel Load, lbs 500 Weld Time: 6 cycles Weld Current: 5200 Amps/weld Weld Pressure: 225 lbs/weld 0 0 1 2 3 4 Number of Welds [Reference: The projection welding of 0.010 and 0.020 inch steel sheet, Welding Journal Research Supplement, 29(9), p.3-13, Nippes & Gerken]

  30. Projection Design for Light-Gauge Steels 0.010” 0.020” 0.040” 0.062” 0.125” Projection Diameter in. Sheet Thickness in. Projection Height in. Punch Top Diameter in. Punch Height in. 30° 0.010 0.110 0.015 0.020 0.110 0.015 0.040 0.140 0.025 0.058 0.035 0.062 0.170 0.042 0.094 0.045 0.125 0.300 0.055 0.176 0.058 30° 30° [Reference: The projection welding of 0.010 and 0.020 inch steel sheet, Welding Journal Research Supplement, 29(9), p.3-13, Nippes & Gerken]

  31. Typical Embossed Projection Design for Heavy-Gauge Steel Sheets 120° 60° 90° 0.52” 45° 0.15” 0.45” 0.094” 0.50” 0.25” [Reference: Resistance Welding Manual, p.3-4, RWMA]

  32. Recommended Projection Geometries and Punch & Die Design for Heavy-Gauge Steel Sheets [Reference: Resistance Welding Manual, p.3-15, RWMA]

  33. Projection Dimensions Vs. Sheet Thickness 0.60 0.50 Diameter 0.40 Projection Dimension, inches 0.30 [Reference: Projection welding of steel in heavy gauges and in dissimilar thicknesses, Welding Journal Research Supplement, 31(3), p.113s-125s, Nippes & Gerken] 0.20 Height 0.10 0 0.10 0.20

  34. Electrode Force and Current Sequence for Heavy-Gauge Steel Sheets Current Force Time

  35. Electrode Force and Current Sequence for Heavy-Gauge Steel Sheets (CONT.) Current Force Time

  36. Nugget Vs. Current for Different Weld Times 0.8 0.6 Diameter, inches Weld Time: 150 cycles Weld Time: 200 cycles Weld Time: 250 cycles Weld Time: 300 cycles 0.4 20,000 22,000 24,000 26,000 28,000 30,000 Welding Current, Amps [Reference: Projection welding of steel in heavy gauges and in dissimilar thicknesses, Welding Journal Research Supplement, 31(3), p.113s-125s, Nippes & Gerken]

  37. Nugget Size Vs. Welding Current for Different Electrode Forces 0.8 0.6 Diameter, inches 0.4 Electrode Force: 3000 lbs Electrode Force: 4000 lbs Electrode Force: 5000 lbs 20,000 22,000 24,000 26,000 28,000 30,000 Welding Current, Amps [Reference: Projection welding of steel in heavy gauges and in dissimilar thicknesses, Welding Journal Research Supplement, 31(3), p.113s-125s, Nippes & Gerken]

  38. Weld Strength Vs. Welding Current Two step current start, total weld time 250 cycles 20 cycles for each step 225 cycles weld time, forge force applied for first 25 cycles and end of weld 28 24 Shear Strength 20 Load, lbs x 102 16 Normal Strength 12 8 15,000 20,000 25,000 30,000 Welding Current, Amps [Reference: Projection welding of steel in heavy gauges and in dissimilar thicknesses, Welding Journal Research Supplement, 31(3), p.113s-125s, Nippes & Gerken]

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