Capacitor discharge welding (CD welding)

EXPERT has been building and developing pulse transformers for capacitor discharge welding for many years. The process is characterised by the fact that large amounts of energy can be introduced into the workpiece within a relatively short time (typically 5 ms to 100 ms). The energy for the welding process is stored on capacitor banks. By selective discharge via a matching transformer, a current pulse is generated which welds the components together. The welding process itself is a projection welding process in most applications.

Due to the high energy input, the process also enables the welding of large-format components and critical material pairings. This process is used to weld gear wheels for gearboxes in the automotive industry, for example.

Another characteristic is the optimal energy utilisation. During the welding process, only very small heat-affected zones are created in the component. The energy used is almost exclusively used to melt the material directly at the joint.

Welding currents of up to 1,000,000 A have already been achieved in systems with EXPERT transformers.

Another advantage of capacitor discharge welding is the relatively low mains load, as the capacitors act as an energy buffer and can be recharged evenly during the breaks between the welds.

The systems are mainly used in large-scale production in automated joining stations.

In this process, the matching transformer (impulse transformer) not only assumes the function of optimal energy feed into the joining process. With its properties, it also decisively influences the temporal course of the welding current (pulse shape) and thus decisively influences the welding process.

EXPERT has many years of experience in the dimensioning of pulse transformers in the high current range. Our own calculation and simulation tools enable the optimum design and adaptation of the transformer to customer-specific requirements. We are also happy to support you with our experience in optimising your welding process.

An overview of various transformers is listed below. This represents a selection. The given data for Ipeak (peak current), tpeak (current rise) and t50% (pulse width) are calculated for a typical machine impedance and give an orientation.

Data sheet Type Pulse energy[kJ] U1N [V]
Secondary voltages U20 [V] Ipeak[kA] tpeak[ms] t50%[ms]
TIM0030/0004 X-20,0-30-2000-T 1,2 2000 20,0 12 2,2 7,0
TIM0080/0001 X-7,5-80-3000-T 6 3000 7,5 22 7,0 23,0
TIM0100/0012 X1-10,0-100-2000-TM 5 2000 10,0 65 5,0 14,0
TIM0120/0001 X-45,0-120-900-TM 6 900 15,0 40 2,8 7,0
TIM0120/0001 X-45,0-120-900-TM 6 900 22,5 46 2,3 5,0
TIM0120/0001 X-45,0-120-900-TM 6 900 45,0 66 1,3 2,7
TIM0150/0002 9/1-20,6-150-3300-TM 10 3300 20,6 122 4,0 9,0
TIM0180/0001 9-50,0-180-3000-TM 5 3000 25,0 107 2,4 5,0
TIM0180/0001 9-50,0-180-3000-TM 5 3000 50,0 134 1,5 3,0
TIM0190/0001 X-61,0-190-3200-TM/M8 12 3200 61,0 51 4,2 10,5
TIM0230/0001 X1-20,6-230-3300-TM 15 3300 20,6 136 5,0 12,0
TIM0250/0001 10/1-10,0-250-3000-T 20 3000 10,0 295 13,0 24,0
TIM0250/0004 10/1-11,0-250-3300-TM 20 3300 11,0 114 10,0 25,0
TIM0250/0005 10/2-22,0-250-3300-TM 20 3300 11,0 110 10,0 26,0
TIM0250/0005 10/2-22,0-250-3300-TM 20 3300 13,2 123 9,0 20,0
TIM0250/0005 10/2-22,0-250-3300-TM 20 3300 16,5 141 7,8 19,0
TIM0250/0005 10/2-22,0-250-3300-TM 20 3300 22,0 166 6,2 14,0
TIM0250/0007 10/2-26,4-250-3300-TM 20 3300 13,2 124 9,0 24,0
TIM0250/0007 10/2-26,4-250-3300-TM 20 3300 16,5 143 7,7 18,0
TIM0250/0007 10/2-26,4-250-3300-TM 20 3300 22,0 168 6,2 14,0
TIM0250/0007 10/2-26,4-250-3300-TM 20 3300 26,4 183 5,4 11,0
TIM0260/0001 X-48,2-260-2750-TM 10 2750 12,1 92 6,2 16,0
TIM0260/0001 X-48,2-260-2750-TM 10 2750 24,1 138 3,8 7,5
TIM0260/0001 X-48,2-260-2750-TM 10 2750 48,2 162 2,5 4,5
TIM0350/0001 X-91,7-350-3200-TM 6 3200 91,7 50 2,0 4,0
TIM0350/0002 X-48,8-350-4000-TM 26 4000 12,2 111 9,5 27,0
TIM0350/0002 X-48,8-350-4000-TM 26 4000 24,4 175 5,9 14,0
TIM0350/0002 X-48,8-350-4000-TM 26 4000 48,8 242 3,5 6,5
TIM0350/0003 X-44,0-350-3300-TM 25 3300 11,0 107 7,5 28,0
TIM0350/0003 X-44,0-350-3300-TM 25 3300 22,0 173 5,3 12,0
TIM0350/0003 X-44,0-350-3300-TM 25 3300 44,0 250 3,2 6,0
TIM0350/0004 X-44,4-350-3200-TM 38 3200 11,1 106 12,0 36,0
TIM0350/0004 X-44,4-350-3200-TM 38 3200 22,2 175 7,7 18,0
TIM0350/0004 X-44,4-350-3200-TM 38 3200 44,4 254 4,6 9,0
TIM0350/0005 X-48,8-350-4000-TM 26 4000 12,2 111 9,5 27,0
TIM0350/0005 X-48,8-350-4000-TM 26 4000 24,4 175 5,9 14,0
TIM0350/0005 X-48,8-350-4000-TM 26 4000 48,8 242 3,4 6,5
TIM0360/0001 10-25,6-360-3300-TM 30 3300 12,8 142 8,0 16,0
TIM0360/0001 10-25,6-360-3300-TM 30 3300 15,3 151 7,0 14,0
TIM0360/0001 10-25,6-360-3300-TM 30 3300 19,2 173 6,0 12,0
TIM0360/0001 10-25,6-360-3300-TM 30 3300 25,6 191 5,0 9,0
TIM0380/0001 X-133,3-380-1000-T-M8Pr 10 1000 44,4 36 4,0 11,0
TIM0380/0001 X-133,3-380-1000-T-M8Pr 10 1000 66,7 44 3,2 7,0
TIM0380/0001 X-133,3-380-1000-T-M8Pr 10 1000 133,3 64 1,8 3,5
TIM0380/0002 X-125,0-380-1500-TM-M8Pr 36 1500 125,5 106 4,0 7,5
TIM0380/0003 X-59,1-380-1300-T 13 1300 29,5 134 3,7 7,5
TIM0380/0003 X-59,1-380-1300-T 13 1300 39,4 153 3,0 6,0
TIM0380/0003 X-59,1-380-1300-T 13 1300 59,1 177 2,2 4,0
TIM0380/0004 X-125,0-380-1500-TM-M8Pr 36 1500 125,0 106 4,0 7,5
TIM0400/0003 X-41,3-400-3300-TM 40 3300 10,3 104 11,0 40,0
TIM0400/0003 X-41,3-400-3300-TM 40 3300 13,8 130 10,0 35,0
TIM0400/0003 X-41,3-400-3300-TM 40 3300 20,6 177 7,4 20,0
TIM0400/0003 X-41,3-400-3300-TM 40 3300 41,3 265 5,0 9,0
TIM0400/0009 X-22,0-400-3300-TM 40 3300 11,0 108 11,0 45,0
TIM0400/0009 X-22,0-400-3300-TM 40 3300 13,2 125 10,0 32,0
TIM0400/0009 X-22,0-400-3300-TM 40 3300 16,5 146 8,5 22,0
TIM0400/0009 X-22,0-400-3300-TM 40 3300 22,0 182 7,0 19,0
TIM0410/0001 X-45,0-410-900-T 12 900 22,5 114 5,2 11,0
TIM0410/0001 X-45,0-410-900-T 12 900 30,0 132 4,0 8,0
TIM0410/0001 X-45,0-410-900-T 12 900 45,0 143 3,8 5,8
TIM0410/0002 X-45,0-410-900-T 18 900 22,5 131 5,0 9,0
TIM0410/0002 X-45,0-410-900-T 18 900 30,0 151 3,9 7,5
TIM0410/0002 X-45,0-410-900-T 18 900 45,0 173 2,8 5,5
TIM0600/0001 X-48,8-600-4000-T 52 4000 12,2 125 11,0 40,0
TIM0600/0001 X-48,8-600-4000-T 52 4000 24,4 210 7,0 19,0
TIM0600/0001 X-48,8-600-4000-T 52 4000 48,8 312 4,2 8,0
TIM0650/0001 X-27,5-650-3300-TM 60 3300 13,8 142 10,0 35,0
TIM0650/0001 X-27,5-650-3300-TM 60 3300 16,5 164 9,5 30,0
TIM0650/0001 X-27,5-650-3300-TM 60 3300 20,6 193 8,5 24,0
TIM0650/0001 X-27,5-650-3300-TM 60 3300 27,5 236 7,0 17,0
TIM0850/0001 10/2-61,1-850-3300-TM 36 3300 30,6 214 5,5 12,0
TIM0850/0001 10/2-61,1-850-3300-TM 36 3300 36,7 234 4,9 10,0
TIM0850/0001 10/2-61,1-850-3300-TM 36 3300 45,8 260 4,0 8,0
TIM0850/0001 10/2-61,1-850-3300-TM 36 3300 61,1 295 3,2 6,5
TIM0860/0001 10/2-53,2-860-3300-TM 36 3300 26,6 197 6,1 13,5
TIM0860/0001 10/2-53,2-860-3300-TM 36 3300 31,1 213 5,5 11,5
TIM0860/0001 10/2-53,2-860-3300-TM 36 3300 41,3 248 4,3 9,5
TIM0860/0001 10/2-53,2-860-3300-TM 36 3300 53,2 279 3,6 6,5
TIM1000/0002 X-480,0-1000-4000-PT100 20 4000 120,0 56 2,1 5,5
TIM1000/0002 X-480,0-1000-4000-PT100 20 4000 160,0 63 1,8 4,5
TIM1000/0002 X-480,0-1000-4000-PT100 20 4000 240,0 83 1,3 2,8
TIM1000/0002 X-480,0-1000-4000-PT100 20 4000 480,0 109 0,7 1,3
TIM1600/0001 X-47,8-1600-3300-TM 80 3300 23,9 228 8,7 24,0
TIM1600/0001 X-47,8-1600-3300-TM 80 3300 28,7 257 7,6 18,0
TIM1600/0001 X-47,8-1600-3300-TM 80 3300 35,9 296 6,6 15,0
TIM1600/0001 X-47,8-1600-3300-TM 80 3300 47,8 350 5,3 12,0
TIM2000/0001 X-68,8-2000-3300-TM 120 3300 34,4 304 8,0 22,0
TIM2000/0001 X-68,8-2000-3300-TM 120 3300 41,3 340 7,0 16,0
TIM2000/0001 X-68,8-2000-3300-TM 120 3300 51,6 386 6,0 13,0
TIM2000/0001 X-68,8-2000-3300-TM 120 3300 68,8 451 5,0 10,0