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### Transcript of Jim Cuhel Welding Engineer Miller Electric Mfg. Co

• Slide 1
• Jim Cuhel Welding Engineer Miller Electric Mfg. Co.
• Slide 2
• Short Arc RMD Taking Control Time(mS) Voltage (volts ) Current (amps) Typical STD MIG Waveform 150 IPM.035" S-6 912914916918920922924926928930 00 650 12100 18150 24200 30250 36300 42350 Voltage Current Time(mS) Voltage (volts) Current (amps) Typical RMD Waveform 150 IPM.035" S-6 108109.5111112.5114115.5117118.5120121.5123 00 550 10100 15150 20200 25250 30300 35350 40400 Voltage Current
• Slide 4
• What Is RMD? Current Voltage Current (amps) Time (Ms) 300301.5 303 304.5306307.5309310.5 0 50 100 150 200 250 300 WET PINCHCLEAR BLINK PREDICT BLINK ARC BALL BACKGROUND PRE-SHORT
• Slide 5
• dl Wire Puddle Necking Region Power Density in the Necking Region Molten Wire
• Slide 6
• Time Power in Necking Region Necking Begins Short Circuit Clears (standard MIG) Detect Clearing Event Reduce Current (hence, power) Short Circuit Clears at Much Lower Power Level (RMD)
• Slide 7
• Slide 8
• Heat Input Arc Heating Term Resistive Heating
• Slide 9
• How Much Energy is Needed to Burn off the Incoming Wire? First we need to bring the wire temperature from something near room temp up to the melting point of the wire: Temperature Change: Heat Input Required to Effect Temperature Change: (where C=specific heat of material and M wire = Mass of the wire being heated) Then, we need to supply sufficient energy to cause a phase transformation from solid to liquid (we need to melt it): (where H m =latent heat of fusion of material) So, the total* energy required to burn off the incoming wire is:
• Slide 10
• Putting This Knowledge to Use Heat In = + I 2 (t)*I(t)*
• Slide 11
• ARC ON Little l I(t) I(t)* I 2 (t)* 1/2 -Jset Arc Heating Resistive Heating Jset = (Heat in @ Stickout) Error Term ARC OFF Jset
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