A plasma arc torch comprises an electrode, a tip, and a shape memory alloy (SMA) starter. The electrode and the tip that are aligned concentrically with a gap therebetween. The electrode is adapted for electrical connection to a cathodic side of a power supply and the tip is adapted for electrical connection to an anodic side of the power supply during piloting. The SMA starter comprises a SMA starter element disposed between the electrode and the tip and is configured deform when heated. A deformation of the SMA starter element draws a pilot arc that extends at least partially through the gap between the electrode and the tip.

A welding or additive manufacturing system includes a contact tip assembly having first and second exit orifices. A wire feeder is configured to deliver a first and second wire electrodes through the exit orifices. An arc generation power supply is configured to output a current waveform to the wire electrodes simultaneously, through the contact tip assembly. The current waveform includes a bridging current portion, and a background current portion having a lower current level than the bridging current portion. The bridging current portion has a current level sufficient to form a bridge droplet between the wire electrodes before the bridge droplet is transferred to a molten puddle during a deposition operation. Solid portions of the wire electrodes do not contact each other during the deposition operation. The bridge droplet is transferred to the molten puddle during a short circuit event between the molten puddle and the wire electrodes.

Systems and methods to provide welding-type arc starting and stabilization with reduced open circuit voltage are disclosed. An example welding-type power supply includes: power conversion circuitry configured to convert input power to welding-type power; and control circuitry configured to: control the power conversion circuitry to output a voltage pulse at a first voltage; determine whether the power conversion circuitry outputs current during the voltage pulse; in response to determining that there is less than a threshold output current during the voltage pulse, control the power conversion circuitry to turn off an output or output a second voltage that is less than the first voltage; and in response to determining that the power conversion circuitry outputs at least the threshold output current during the voltage pulse, control the power conversion circuitry to output the welding-type power.

Systems and methods to provide welding-type arc starting and stabilization with reduced open circuit voltage are disclosed. An example welding-type power supply includes: power conversion circuitry configured to convert input power to welding-type power; and control circuitry configured to: control the power conversion circuitry to output a voltage pulse at a first voltage; determine whether the power conversion circuitry outputs current during the voltage pulse; in response to determining that there is less than a threshold output current during the voltage pulse, control the power conversion circuitry to turn off an output or output a second voltage that is less than the first voltage; and in response to determining that the power conversion circuitry outputs at least the threshold output current during the voltage pulse, control the power conversion circuitry to output the welding-type power.

A method comprising an arc ignition phase (IP), an arc-stabilizing phase (AP) and a stable arc phase (SP). The arc stabilizing phase comprises an initial sub-phase (IS) comprising the step of feeding at least one hot wire (4, 12) at constant feed speed and a main sub-phase (MS) comprising the steps of feeding said hot wire at constant feed speed and feeding at least one cold wire (22) at constant feed speed. The stable arc phase comprises the steps of continuously adjusting the feed speed of the hot wire and continuously adjusting the feed speed of the cold wire. The invention also relates to a welding apparatus (1) for carrying out the method. The welding apparatus comprises a hot wire feeding means (150), a contact means (2), a cold wire feeding means (35) and a control unit (31). The control unit is adapted to control said hot wire feeding means to feed the hot wire at a constant feed speed during the initial sub-phase, feed the hot wire at a constant feed speed during the main sub-phase and to continuously during the stable arc phase adjust the feed speed of the hot wire. The control unit is adapted to control said cold wire feeding means to feed the cold wire at a constant feed speed during the main sub-phase and continuously during the stable arc phase adjust the cold wire feed speed.

A method comprising an arc ignition phase (IP), an arc-stabilizing phase (AP) and a stable arc phase (SP). The arc stabilizing phase comprises an initial sub-phase (IS) comprising the step of feeding at least one hot wire (4, 12) at constant feed speed and a main sub-phase (MS) comprising the steps of feeding said hot wire at constant feed speed and feeding at least one cold wire (22) at constant feed speed. The stable arc phase comprises the steps of continuously adjusting the feed speed of the hot wire and continuously adjusting the feed speed of the cold wire. The invention also relates to a welding apparatus (1) for carrying out the method. The welding apparatus comprises a hot wire feeding means (150), a contact means (2), a cold wire feeding means (35) and a control unit (31). The control unit is adapted to control said hot wire feeding means to feed the hot wire at a constant feed speed during the initial sub-phase, feed the hot wire at a constant feed speed during the main sub-phase and to continuously during the stable arc phase adjust the feed speed of the hot wire. The control unit is adapted to control said cold wire feeding means to feed the cold wire at a constant feed speed during the main sub-phase and continuously during the stable arc phase adjust the cold wire feed speed.

An arc welding system includes a temperature determination module and a parameter optimization module. The temperature determination module is configured to determine, from among a plurality of possible temperature categories, a temperature category of an electrode during an interruption to an arc welding process on a workpiece based on a comparison of information indicative of a duration of the interruption to one or more timing thresholds. An electric arc between the electrode and the workpiece is extinguished during the interruption. The parameter optimization module is configured to set one or more current parameters of an output current to be applied to the arc welding process when the arc welding process restarts. The current parameters are based on the temperature category of the electrode determined by the temperature determination module.

An arc welding system includes a temperature determination module and a parameter optimization module. The temperature determination module is configured to determine, from among a plurality of possible temperature categories, a temperature category of an electrode during an interruption to an arc welding process on a workpiece based on a comparison of information indicative of a duration of the interruption to one or more timing thresholds. An electric arc between the electrode and the workpiece is extinguished during the interruption. The parameter optimization module is configured to set one or more current parameters of an output current to be applied to the arc welding process when the arc welding process restarts. The current parameters are based on the temperature category of the electrode determined by the temperature determination module.

An example system includes an additive manufacturing tool configured to receive a wire from a wire feeder, to receive current from a power source, and to supply the wire to a workpiece during an additive manufacturing process, and a mechanical oscillation system configured to mechanically oscillate a structural component toward and away from the workpiece, wherein the structural component is external to the wire feeder and the power source.

An example system includes an additive manufacturing tool configured to receive a wire from a wire feeder, to receive current from a power source, and to supply the wire to a workpiece during an additive manufacturing process, and a mechanical oscillation system configured to mechanically oscillate a structural component toward and away from the workpiece, wherein the structural component is external to the wire feeder and the power source.