Description: Check out my other items! Be sure to add me to your favorites list! Table of Contents Chapter 1 INTRODUCTION 1-1. Resistance welded products 25 1-2. Poorly welded products Weld schedule problems Excessive weld times Two weld hits necessary Inadequate trial and error Big mistakes 26 27 27 27 27 28 1-3. Weld parameter combination Robust weld schedule Many weld schedules work OK in short term 28 29 29 1-4. Weld schedule developed from process windows and lobes Is best for long run Successful example Case for Organized development Only one setting to adjust on all machines 30 30 31 31 1-5. Justification 32 1-6. Process windows introduction 32 1-7 Weld lobes introduction Weld lobes for different parameters Weld lobes for three parameters Middle of volume reveals optimum combination 33 35 36 37 1-8 History Early introduction to the development of weld schedules from process windows and lobes Industry examples Further discussion of the savings Savings estimate stands up Cheaper the first time 38 38 39 40 40 Chapter 2 BACKGROUND 2-1. Why weld lobes and process windows Misleading visual indications on weld surface 41 42 2-2. Weld metallographs 42 2-3. Adjustment for visual appearance Problem with visual appearance Spreading a habit No color with Aluminum or Titanium 44 44 44 45 2-4. Automatic or semi-automatic control 45 2-5. Visual inspection in arc welding 45 2-6. Resistance weld testing for hidden weld characteristics Repeatability is necessary 46 46 2-7. The weld schedule 47 2-8. Other resistance welding processes % heat setting weld controls Constant current weld controls Settings that effect the outcome 48 48 49 49 2-9. Standard weld schedule for resistance welding 49 2-10. Experiment: Weld Schedule Selection 50 2-10.1 Purpose 50 2-10.2 Resources 50 2-10.3 Procedure 50 2-10.4 Results 51 2-10.5 Conclusion 51 2-11. Need for a custom weld schedule Resistance welding behavior Some minimum amount of a parameter necessary The solution 52 53 53 53 2-12. Complicating factors Shunting Metal thickness ratios Polarity Other complications 54 54 54 55 55 2-13. The weld schedule developer Technician #1 Machine standards allowed for his behavior His behavior limited Technician #2 56 56 56 57 57 2-14. Robust weld settings Example of what is not robust 57 58 2-15. Weld schedule development environment 59 2-16. Need for a procedure 60 2-17. Need for written records Without written records Hidden benefit from written records Three days wasted 60 61 61 61 2-18. Repair weld facilities Repair weld process control oversight 62 62 Chapter 3 WELD STRENGTH VS. WELD SIZE 65 3-1. Why measure weld size 65 3-2. Weld size strength relationship 65 3-3. Maximum strength 68 3-4. Process capability study When size does not assure strength Introduction to experiments 69 69 69 3-5. Experiment: Weld strength and size relationship in mild steel 70 3-5.1. Purpose 70 3-5.2. Resource 70 3-5.3. Procedure 70 3-5.4. Results 72 3-5.5. Discussion Column 1: % heat Column 2 & 3: test & failure mode Column 4 & 5: shear strength pounds & kilograms Column 6 & 7: nugget diameter inches & millimeters 72 72 73 73 73 3-5.6. Results: Strength VS. size 74 3-5.7. Discussion 74 3-5.8. Results: Weld nugget size vs. % heat 75 3-5.9. Discussion Not a trivial problem 75 76 3-5.10. Recommendations for further experimentation Note 1: problem with high % heat Note 2: problem with raising tap Note 3: value of this method is shown Note 4: problem from inadequate written records 76 77 77 77 78 3-6. Experiment: Weld strength and size relationship in one aluminum application 78 3-6.1. Purpose 78 3-6.2. Resources 78 3-6.3. Procedure 79 3-6.4. Results 80 3-6.5. Discussion 80 3-6.6. Results: Weld nugget size vs. strength 81 3-6.7. Discussion 81 3-6.8. Results: Weld % heat vs. shear strength 82 3-6.9. Discussion Aluminum surface preparation problem Recommended aluminum surface preparation Inadequate amount of data However data was adequate for the conclusion! 82 82 83 83 83 3-6.10. Recommended additional exp. Note 1: number of data points Note 2: conclusions about aluminum, resistance welding from this experiment should be limited Note 3: limitations from absence of rec. Note 4: even experiments with problems should be reported Conclusions from both experiments Typical experiment size 84 84 84 85 85 86 86 3-7. Weld size and strength data from US Government Military Specification Mil-W-6858D Effect of metal strength on the weld strength requirement Sources for weld strength and size data 88 89 89 3-8. Adequate written records When weld strength is difficult to measure in production Inadequate data even from good setups Later on without written records 89 90 90 90 3-9. Example of unshared findings 91 3-10. Note about the remainder of the book 91 Chapter 4 PROCESS WINDOWS 4-1. Process window introduction Common example 93 93 4-2. Weld % heat and weld current Tip-off: weld % heat not absolute Limitation of weld % heat process window 93 94 94 4-3. Other weld characteristics goals Process window goals Electrode sticking 95 95 96 4-4. Fragile weld schedules 96 4-5. Preliminary view 96 4-6. Squeeze time process window Squeeze time periods 97 97 4-7. Shift to shift variations During second shift During first shift Remedy Common problems Solution discussion 98 98 99 99 99 100 4-8. Undersized air supply components 100 4-9. Pressure switch initiation Another way for pressure switch utilization 101 102 4-10. Weld current process window 102 4-11. Weld time process window Benefits of longer weld time 103 104 4-12. Hold time process windows Weld valve mechanical delay note Perils of long hold time 105 106 106 4-13. Electrode force process window 108 4-14. Process window summary 109 4-15. Experiment: Weld current and time windows 110 4-15.1. Performance objective Develop weld current and time windows for optimum welding 110 110 4-15.2. Resources 110 4-15.3. Weld current window procedure 111 4-15.4. Weld current window data 111 4-15.5. Weld time window procedure 112 4-15.6. Weld time window data 112 4-15.7. Conclusion 112 4-15.8. Recommendations Added weld sample tests Added experimental goals 112 113 113 Chapter 5 WELD LOBES 5-1. Weld lobe introduction Lobe determines the center 115 115 5-2. Weld current range 116 5-3. Weld time range 117 5-4. Weld lobe for current and time 117 5-5. When to start with a current and time lobe 118 5-6. About the shape of a lobe 119 5-7. Experiment: Weld lobe for current and time 119 5-7.1. Performance objective 119 5-7.2. Resources 120 5-7.3. Weld current and time lobe procedure 120 5-7.4. Weld current and time lobe data 121 5-7.5. Weld current and time result 122 Chapter 6 WELD FORCE LOBES 6-1. Introduction 123 6-2. Weld current and force lobe 123 6-3. Why current and force lobe development A case for current and force lobe first 123 124 6-4. Note: look at slope, pulsation………. 124 6-5. Note: Assumption of best electrodes 124 6-6. Note: Assumption of the best resistance welding process 125 6-7. The lobe gets to the answer quickly Weld lobe development cuts to chase real fast 125 125 6-8. Some cases that do not work Process window and lobe experiments analytically sort out conclusions: good or bad 125 126 6-9. Back to the current and force lobe 126 6-10. The chart 127 6-11. Discussion for weld current and force lobe result Good welds Bad welds Cold welds Hot welds 127 128 128 128 128 6-12. Weld force and time lobe A case for weld force and time lobe first 128 128 6.13. Back to the force and time lobe 129 6-14. The chart 129 6-15. Discussion for weld force and time lobe Good welds Bad welds Cold welds Hot welds 130 130 130 130 130 6-16. Summary 131 6-17. Weld lobe procedure (for optimum weld size with no expulsion) Resources: Machine setup: Complicating factors: Current window: Weld time window: Plot data Force lobe 132 132 132 133 133 134 134 134 6-18. Experiment: Weld lobe for current and force 135 6-18.1. Performance objective 135 6-18.2. Resources (same as Experiment 5-7) 135 6-18.3. Weld current and force lobe procedure 136 6-18.4. Weld current and force lobe data 136 6-18.5. Weld current and force lobe results 137 6-18.6. Conclusion 137 Chapter 7 WELD SCHEDULE EXAMPLE DEVELOPED FROM WELD LOBES 7-1. The setup 139 7-2. Seasoned electrodes 141 7-3. Worn electrode condition setup Electrode life observation Worn electrodes from factory production did not work for simulation Worn condition confirmation Electrode parallelism chart 141 141 142 142 143 7-4. The weld schedule chart 143 7-4.1. Weld schedules for bare and electroplate galvanized steel 144 7-5. Complicating factors For example 146 147 7-6. Use of the values The alternative 148 148 Chapter 8 PROCESS WINDOWS FOR OTHER SETTINGS 8-1. Introduction 149 8-2. Upslope Benefits of low starting heat Summary recommendation About the shape of a lobe Theoretical effect of upslope on the weld lobe process window Caution with some weld equipment Caution for certain aluminum materials and other materials that may be slope sensitive Note: sometimes slope without choice 149 150 151 151 151 152 153 153 8-3. Pulsation Typical pulsation weld schedule Theoretical effect of pulsation on the weld lobe process window Why go to the trouble Automobile wheel weld impulse schedule Impulse schedule for steel wheel welding Narrow flange width welding Pulsation equipment warning 154 154 154 155 155 155 156 156 156 8-4. Decay or temper current Theoretical current decay lobe in aluminum Summary decay current tip Other decay or temper studies 157 157 158 159 8-5. Stepper lobe for spot welding Problem One solution Advanced stepping of weld time and/or force 159 159 160 162 8-6. Current vs. force lobe results for bad fitting parts Test simulation for poorly fitting aluminum parts Use of electrically insulated shim 163 163 163 8-7. Experiment: Stepper lobe for current & weld count 164 8-7.1. Performance objective 164 8-7.2. Resources 164 8-7.3. Stepper lobe procedure 165 8-7.4. Stepper lobe data 166 8-7.5. Weld current vs. count lobe results 167 8-7.6. Conclusion 167 8-8. Experiment: Adjacent welds supplement 167 8-8.1. Performance objective 167 8-8.2. Procedure 168 8-8.3. Data for second weld 168 8-8.4. Results 168 8-8.5. Discussion Repeated for many applications in one facility Adjacent weld tip Remaining work 169 171 171 171 Chapter 9 EXPANDING PROCESS WINDOWS AND LOBES 9-1. List of process windows that can be developed Section summary 173 174 9-2. List of weld lobes that can be developed 175 9-3. List of weld characteristics to be indicated on a weld lobe chart Section summary 176 177 9-4. Three dimensional weld lobes Expanding the value of the experiment 178 178 9-5. Advanced experimental tools 179 9-6. Long weld time example 179 9-7. Avoid blindness from experimental plan 180 9-8. Design of experiments Not a substitute for the basics 180 181 9-9. Other applications Other manufacturing processes 182 182 9-10. Conclusion Resistance welding benefits, successful in certain large industries, are available to other industries 183 183 Please email with any questions. The unit may be packaged and shipped or can be picked up in Chattanooga, TN.
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End Time: 2024-09-27T14:56:19.000Z
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