Physics of Projection Welding Projection Physics Lesson Objectives
Physics of Projection Welding
Projection Physics Lesson Objectives When you finish this lesson you will understand: • The collapse of the projection during welding • Factors effecting the projection collapse Learning Activities 1. View Slides; 2. Read Notes, 3. Listen to lecture 4. Do on-line workbook Keywords Current Concentration, Projection Collapse
Projection Welding of Low Carbon Steel (Two Equal Thicknesses) [Reference: Resistance Welding Manual, p. 3 -13, RWMA]
Functions of Electrode Force l l 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.
Tensile-Shear Strength (lbs) Nugget Diameter Effect of Weld Time Projection Collapse Weld Time (Cycles)
Factors Affecting Heat Balance • Projection Design • Part Thickness • Die Material Backing up the Weld • Metal Conductivity • Heating Speed
Projection Weld Formation Stage 1 Stage 3 Stage 2 Stage 4 [Reference: Resistance Welding Manual, p. 3 -9, RWMA]
Projection Weld Formation (CONT. ) Stage 5 Stage 7 Stage 6 Stage 8 [Reference: Resistance Welding Manual, p. 3 -9, RWMA]
Link to projection weld video
Recommended Projection Designs T L H D T: D: H: L: Thickness of thinnest outside piece Diameter of projection Height of projection Minimum contacting overlap T(in. ) D(in. ) H(in. ) L(in. ) 0. 010 -0. 014 0. 016 -0. 020 0. 025 0. 031 -0. 034 0. 044 -0. 050 0. 062 -0. 070 0. 078 0. 094 0. 109 0. 125 0. 140 0. 156 0. 171 0. 187 0. 203 0. 250 0. 055 0. 067 0. 081 0. 094 0. 119 0. 156 0. 187 0. 218 0. 250 0. 281 0. 312 0. 343 0. 375 0. 406 0. 437 0. 531 0. 015 0. 017 0. 020 0. 022 0. 028 0. 035 0. 041 0. 048 0. 054 0. 060 0. 066 0. 072 0. 078 0. 085 0. 091 0. 110 1/8 5/32 3/16 7/32 9/32 3/8 7/16 1/2 5/8 11/16 3/4 13/16 7/8 15/16 1 1 -1/4 [Reference: Recommended practice for resistance welding, AWS Document C 1. 1 -66, AWS, 1966]
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]
Variation in Weld Head Position during Projection Welding 0. 062 -inch Thick Steel Initial Collapse Final Collapse Current Electrode Position Weld Nugget Expansion 60 Cycle Timing Trace [Reference: A study of projection welding, Welding Journal Research Supplement, 27(12), p. 712 s-713 s, Hess & Childs] Cool
Variation in Weld Force during Projection Welding 0. 125 -inch Thick Steel 1000 lbs. Weld Time [Reference: A study of projection welding, Welding Journal Research Supplement, 27(12), p. 712 s-713 s, Hess & Childs] Cool
Effect of Welding Current, Amps 20, 000 30 cycles 45 cycles 60 cycles 15, 000 10, 000 Projection: D = 0. 40” H = 0. 027” Electrode Force: 1500 lbs 5, 000 0 0. 25 0. 50 Diameter of Fused Zone, in. [Reference: A study of projection welding, Welding Journal Research Supplement, 27(12), p. 712 s-713 s, Hess & Childs]
Relations between Weld Current, Weld Time and Weld Strength on 0. 040 -inch Thick Mild Steel Weld Strength, lbs 1500 Shear 1000 Nominal Tension 500 Projection 10 cycles 15 cycles 20 cycles 4000 5000 D = 0. 10” H = 0. 025” Electrode Force 400 lbs 6000 7000 Welding Current, Amps [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p. 15 s-23 s, Hess & Childs]
Effect of Projection Shape Weld Strength, lbs 1500 Shear 1000 Normal Tension 500 Projections D H 0. 010” 0. 025” 0. 140” 0. 025” 4000 5000 Electrode Force lbs 400 450 6000 Welding Current, Amps 7000 [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p. 15 s-23 s, Hess & Childs]
Fused Zone Diameter, inches Effect of Electrode Material RWMA Classification Group B, Class 12 0. 20 0. 10 RWMA Classification Group A, Class 3 RWMA Classification Group A, Class 2 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. 15 s-23 s, Hess & Childs]
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. 712 s-713 s, Hess & Childs]
Additive Effect of Projection Weld Strengths for Multiple Welded Assemblies Projection: D = 0. 10” H = 0. 025” AISI 1010 AISI 1015 AISI 1020 Weld Strength, lbs 4000 3000 Shear Weld Current: No. of welds x 6340 Amps Electrode Force: No. of welds x 400 lbs Weld Spacing: 0. 75” Weld Time: 15 cycles 2000 1000 Normal Tension 0 0 1 2 3 4 Number of Welds [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p. 15 s-23 s, Hess & Childs]
Variations in Projection Weld Hardness 400 Thickness: 0. 125” Weld Time: 45 cycles Hardness, VPN 1020 300 1015 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. 712 s-713 s, Hess & Childs]
Effect of Material Hardenability on Weld Strength, lbs 1500 Shear 1000 Projection: D = 0. 10” H = 0. 025” Electrode Force: 400 lbs Normal Tension 500 0 4000 Weld Time: 15 cycles 5000 6000 AISI 1015 AISI 1020 7000 Welding Current, Amps [Reference: Further studies in projection welding, Welding Journal Research Supplement, 28(1), p. 15 s-23 s, Hess & Childs]
Projection Height, inches Cold Projection Collapse Annular : 0. 110” Diam. Spherical: 0. 075” Diam. Spherical: 0. 085 Diam. Spherical: 0. 065 Diam. 0. 020 0. 010 0 0 100 200 Electrode Force, lbs 300 [Reference: The projection welding of 0. 010 and 0. 020 inch steel sheet, Welding Journal Research Supplement, 29(9), p. 3 -13, Nippes & Gerken]
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]
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]
Plug Diameter, inches Current Range Characteristics 0. 20 0. 020”-1010 Steel Annular Projection Height: 0. 015” Diameter: 0. 110” Weld Time: 6 cycles Electrode Force: 225 lbs 0. 10 0 2000 Spherical Projection Height: 0. 020” Diameter: 0. 075” Weld Time: 6 cycles Electrode Force: 150 lbs 3000 4000 Weld Current, Amps 5000 [Reference: The projection welding of 0. 010 and 0. 020 inch steel sheet, Welding Journal Research Supplement, 29(9), p. 3 -13, Nippes & Gerken] 6000
Strength Characteristics 0. 020”-1010 Steel Load, lbs 200 Spherical Projection Height: 0. 020” Diameter: 0. 075” Electrode Force: 75 lbs Weld Time: 6 cycles Pickled in 50% HCl Shear Strength Normal Tension 100 0 1000 Annular Projection Height: 0. 016” Diameter: 0. 077” Electrode Force: 110 lbs Shear Strength Normal Tension 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]
Effect of Weld Force on Strength Characteristics Load, lbs Annular Projection Height: 0. 015” Diameter: 0. 110” Weld Time: 6 cycles 200 Electrode Force: 110 lbs Electrode Force: 130 lbs Shear Normal Tension 100 0 2000 0. 020”-1010 Steel 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]
Projection Welding Schedule of Light-Gauge Steels [Reference: Resistance Welding Manual, p. 3 -13, RWMA]
Additive Effect of Multiple Projection Welds Load, lbs Annular Projection Height: 0. 015” Diameter: 0. 110” 1000 Shear Normal Tension Theoretical 0. 020”-1010 Steel 500 0 Weld Time: 6 cycles Weld Current: 5200 Amps/weld Weld Pressure: 225 lbs/weld 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]
Projection Design for Light. Gauge Steels 0. 010” 0. 020” 0. 040” 30° 0. 062” 30° Sheet Projection Punch Top Punch Thickness Diameter Height in. in. in. 0. 010 0. 020 0. 040 0. 062 0. 125 0. 110 0. 140 0. 170 0. 300 0. 015 0. 025 0. 042 0. 055 0. 058 0. 094 0. 176 0. 125” [Reference: The projection welding of 0. 010 and 0. 020 inch steel sheet, Welding Journal Research Supplement, 29(9), p. 3 -13, Nippes & Gerken] 0. 035 0. 045 0. 058
Typical Embossed Projection Design for Heavy-Gauge Steel Sheets 120° 60° 0. 15” 0. 52” 45° 0. 094” 0. 50” 90° 0. 45” 0. 25” [Reference: Resistance Welding Manual, p. 3 -4, RWMA]
Recommended Projection Geometries and Punch & Die Design for Heavy-Gauge Steel Sheets [Reference: Resistance Welding Manual, p. 3 -15, RWMA]
Projection Dimensions Vs. Sheet Thickness Projection Dimension, inches 0. 60 0. 50 0. 40 Diameter 0. 30 [Reference: Projection welding of steel in heavy gauges and in dissimilar thicknesses, Welding Journal Research Supplement, 31(3), p. 113 s-125 s, Nippes & Gerken] 0. 20 0. 10 0 Height 0. 10 0. 20
Current Force Electrode Force and Current Sequence for Heavy-Gauge Steel Sheets Time
Current Force Electrode Force and Current Sequence for Heavy-Gauge Steel Sheets (CONT. ) Time
Nugget Vs. Current for Different Weld Times Diameter, inches 0. 8 0. 6 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. 113 s-125 s, Nippes & Gerken]
Nugget Size Vs. Welding Current for Different Electrode Forces Diameter, inches 0. 8 0. 6 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. 113 s-125 s, Nippes & Gerken]
Weld Strength Vs. Welding Current Load, lbs x 102 28 24 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 Shear Strength 20 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. 113 s-125 s, Nippes & Gerken]
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