miller xmt 350 cc/cv manual

Technical Specifications

Miller XMT 350 CC/CV delivers dual‑mode AC/DC output, 208/230 V AC and 460 V DC, up to 70 A. It supports 350 W (AC) or 250 W (DC) welding, with CC/CV control, 2‑port (MIG/MMA, TIG) config, 12.5 × 9.5 × 4.5 in, 15 lb, UL‑listed, CE‑certified. 100 % duty cycle. 24/7. ETA! Input 2 kW, 50/60 Hz. 100 % duty. BETA!

AC/DC Power Supply

The Miller XMT 350 CC/CV is engineered with a robust dual‑mode power supply that seamlessly switches between AC and DC operation. The unit accepts a standard 208 V ± 10 % or 230 V ± 10 % AC input at 50 Hz or 60 Hz, and a 460 V ± 10 % DC input for high‑current welding tasks. Internally, the power supply employs a high‑efficiency 2 kW transformer coupled with a full‑bridge rectifier that delivers clean, low‑harmonic output. The AC mode provides a 350 W output with a 70 A maximum current, while the DC mode offers up to 250 W with a 70 A peak. The design incorporates a dual‑transformer architecture that allows independent regulation of the AC and DC paths, ensuring optimal voltage regulation and minimal ripple. The power supply features an active cooling system with a 120 mm fan and a temperature‑controlled shutdown to protect the internal components. It meets UL 60950‑1, CE, and CSA standards for safety and electromagnetic compatibility. The input power is converted to a stable 12 V DC rail that powers the control electronics, and a 48 V DC rail that supplies the inverter stage. The inverter uses a 400 MHz switching frequency to minimize audible noise and electromagnetic interference. The overall efficiency of the AC/DC power supply is rated at 88 % at full load, with a typical input current of 10 A for AC mode and 8 A for DC mode. The power supply also includes a built‑in surge protection circuit that limits input voltage spikes to 1.5 kV, protecting the inverter and the welding output. The unit’s compact footprint of 12.5 × 9.5 × 4.5 in and a weight of 15 lb make it suitable for mobile welding applications. Its modular design supports optional accessories.

Current and Voltage Capabilities

The XMT 350 CC/CV offers a versatile current and voltage envelope tailored for both industrial and field welding. In AC mode, the unit can deliver a continuous current up to 70 A, with a voltage range adjustable from 30 V to 200 V for MIG/MMA processes. The DC mode provides the same 70 A peak, but the voltage can be tuned from 30 V to 150 V, accommodating TIG welding and high‑current short‑circuiting. The device supports a 10 A minimum current for fine‑tune precision, and a 10 V minimum voltage for low‑power applications. The current regulation is achieved through a closed‑loop CC/CV system that maintains a constant voltage or current as required. The voltage output can be set in 1 V increments, while the current can be adjusted in 0.5 A steps, allowing precise control over the weld pool. The device’s input voltage tolerance is ±10 % of the nominal 208 V/230 V AC or 460 V DC, ensuring stable operation in varying supply conditions. The internal power electronics are designed to handle up to 2 kW of input power, translating into a maximum output of 350 W (AC) or 250 W (DC). The current and voltage ranges are fully programmable via the touch‑screen interface, and the system logs all settings for repeatability. The XMT 350 CC/CV also features a built‑in voltage drop compensation that automatically adjusts the output to maintain the desired current under load changes. This capability is critical for maintaining weld quality when switching between different electrode or wire diameters. The overall current and voltage performance make the XMT 350 CC/CV a reliable choice for both high‑volume production and on‑site repair tasks. The unit also supports rapid mode switching, allowing the operator to transition between AC and DC with minimal latency, which is essential for multi‑process jobs. Additionally, the XMT 350 CC/CV provides a 5 % tolerance on output voltage under load, ensuring consistent arc stability even when the input supply fluctuates. The device’s firmware includes a self‑diagnostic routine that monitors current ripple and voltage sag, alerting the user to potential issues before they affect weld quality. For applications requiring high‑precision welding, the XMT 350 CC/CV offers a fine‑tune mode that reduces the current step size to 0.1 A, enabling micro‑current control for delicate work. The current and voltage capabilities are also supported by a comprehensive user manual that details calibration procedures, safety guidelines, and troubleshooting steps. The XMT 350 CC/CV’s design incorporates a 5 kW power module that can be swapped for higher‑current applications, and the unit’s modular architecture allows for future firmware upgrades without hardware replacement.!!

Maximum Output

The Miller XMT 350 CC/CV is engineered to deliver peak performance for demanding welding tasks. Its maximum output is defined by a dual‑mode AC/DC architecture that supports up to 70 A of continuous current in both AC and DC configurations. In AC mode, the device can produce a maximum power of 350 W, while in DC mode it delivers 250 W, ensuring that welders have sufficient energy for a wide range of electrode types and wire diameters. The power module is rated for 2 kW of input power, which translates into a robust 70 A output at 460 V DC or 208/230 V AC. This high‑current capability is complemented by a closed‑loop CC/CV control system that maintains a stable voltage or current under load variations, providing consistent arc quality even when switching between thin‑wire and heavy‑gauge applications. The XMT 350 CC/CV also features a rapid‑switching power supply that can toggle between AC and DC modes in less than 50 ms, allowing operators to adapt to multi‑process jobs without downtime. The maximum output is further supported by a 5 kW power module that can be swapped for higher‑current models, making the unit scalable for future needs. Safety is integrated through a built‑in over‑current protection that limits the output to 70 A, preventing damage to both the machine and the workpiece. The device’s firmware includes a diagnostic routine that monitors output voltage ripple, ensuring that the maximum output remains within specified tolerances. For industrial environments, the XMT 350 CC/CV’s maximum output is ideal for high‑volume production lines, while its compact design keeps the overall footprint at 12.5 × 9.5 × 4.5 in, weighing only 15 lb. This combination of power and versatility makes the XMT 350 CC/CV a choice for welders seeking for high maximum output performance!

Port Configuration

The Miller XMT 350 CC/CV features a versatile port layout for a wide range of welding tasks. The unit has two main output ports: a 2‑wire MIG/MMA port and a 3‑wire TIG port. Both are 1‑inch round connectors; the MIG/MMA accepts 1‑wire or 2‑wire cables, while the TIG port is designed for 3‑wire cable, ensuring proper polarity. A separate 1‑inch input port allows the device to be powered from a 120 V or 240 V AC outlet via a standard IEC‑60320 C14 connector. The rear panel also holds a 1‑inch “Auto‑Line” port for automatic line‑sensing and a 1‑inch “Pulse” port for pulse‑controlled output. The quick‑connect system uses a 1‑inch NEMA 4X style connector, providing a secure, weather‑resistant connection suitable for field use. All ports are rated for continuous current and are protected by built‑in over‑current and short‑circuit protection. The ports are arranged on the rear panel for easy access, and each port has a dedicated LED indicator that displays the current mode and status. The Auto‑Line port can be set to automatically detect line voltage and adjust the output accordingly, providing a plug‑and‑play experience. The Pulse port can be configured to generate pulse waveforms with adjustable frequency and duty cycle, useful for pipe welding and other specialized applications. All ports are protected by a built‑in fuse and short‑circuit protection, ensuring safe operation even under heavy load. The modular design also supports optional adapters for specialized cables to meet specific welding requirements for optimal performance! Enjoy precise control!

The Miller XMT 350 CC/CV is engineered for portability and field deployment, with a compact footprint that balances performance and ease of transport. The overall dimensions are 12.5 inches (31.75 cm) in width, 9.5 inches (24.13 cm) in depth, and 4.5 inches (11.43 cm) in height, giving a total volume of approximately 537 cubic inches (8,800 cm³). The unit’s mass is 15 lb (6.8 kg), which includes the internal power supply, inverter board, cooling fan, and all ancillary components. This weight allows a single operator to carry the machine on a standard work cart or a lightweight pallet, and it meets the ergonomic requirements for most mobile welding rigs. The chassis is constructed from a lightweight aluminum alloy frame, which provides structural rigidity while minimizing overall mass. The front panel features a recessed handle that distributes weight evenly, and the rear panel is reinforced to support the power cord and cable connections without compromising the unit’s balance. The XMT 350’s dimensions and weight are optimized to fit within the standard 3‑by‑4‑foot (1.1 by 1.2 m) work area, ensuring that operators can maneuver the machine around tight spaces and access hard‑to‑reach weld locations. The compact size also facilitates storage in standard tool trailers or on‑site storage racks. For field technicians, the 15‑lb weight is well within the recommended limit for handheld or semi‑handheld equipment, reducing fatigue during prolonged use. The design incorporates a low‑profile cooling system that keeps the unit’sheight to a minimum Designed for field use.

Certifications and Standards

The Miller XMT 350 CC/CV complies with a comprehensive suite of international safety, quality, and environmental standards, ensuring reliable operation across diverse welding environments. It is UL Listed (UL 2230) for North American use, CE‑marked for the European Economic Area, and CSA Certified (CSA Z462) for Canadian markets. The inverter meets IEC 60034‑1 for motor safety, IEC 61000‑4 for electromagnetic compatibility, and ISO 9001:2015 for quality management. Environmental compliance is achieved through RoHS Directive 2011/65/EU, WEEE, and REACH, eliminating hazardous substances such as lead, mercury, cadmium, and hexavalent chromium. The device also satisfies the FCC Part 15 Class B limits for radio frequency emissions, ensuring minimal interference with other equipment. Miller’s commitment to safety is further evidenced by the inclusion of a built‑in arc‑flash protection system that adheres to NFPA 70E guidelines, providing a minimum arc‑flash protection level of 80 J/cm². For industrial use, the XMT 350 is compliant with OSHA’s 29 CFR 1910.269, guaranteeing that the equipment meets the required electrical safety standards for hazardous locations. The unit’s thermal management system is validated against IEC 60335‑2‑40, ensuring safe operation under high ambient temperatures. Finally, the XMT 350’s design incorporates the ISO 14001:2015 environmental management framework, demonstrating Miller’s dedication to sustainable manufacturing practices. Together, these certifications provide users with confidence in the machine’s safety, performance, and regulatory compliance across global markets!!!

Operating Modes

The XMT 350 offers versatile operation: MIG/MMA (GMAW) for robust arc welding, TIG (GTAW) for precision, Auto‑Line for automated processes, FieldPro for manual control, and adjustable pulse/constant current settings. Each mode is selectable via intuitive interface, ensuring optimal performance across tasks.!

MIG/MMA (GMAW) Capability

The Miller XMT 350 CC/CV is engineered for high‑performance MIG/MMA (GMAW) welding across a wide range of materials and thicknesses. Its dual‑mode AC/DC output supports 208/230 V AC or 460 V DC, delivering up to 70 A of continuous current. The inverter’s advanced power‑regulation circuitry provides a stable, low‑noise arc, essential for clean welds on thin sheet metal and robust joints on thicker plates. With a 350 W AC or 250 W DC power rating, the unit can handle 0.5 mm to 25 mm carbon steel, stainless steel, and aluminum alloys, offering adjustable voltage, current, and polarity settings to match electrode or wire type. The built‑in pulse‑control feature allows precise pulse frequency and amplitude modulation, improving weld penetration and reducing spatter. The XMT 350’s 2‑port design enables simultaneous MIG/MMA operation on two workpieces, while the integrated 2‑way selector switch lets users switch between AC and DC modes without interrupting the weld. The device’s ergonomic interface includes a full‑color LCD, intuitive rotary encoder, and programmable memory for custom settings, making it suitable for both field and shop applications. Safety is enhanced by built‑in over‑current protection, short‑circuit detection, and a robust chassis that meets UL and CE standards. The XMT 350’s compact footprint (12.5 × 9.5 × 4.5 in) and lightweight construction (≈15 lb) facilitate easy transport, while its 100 % duty cycle ensures continuous operation during demanding welding tasks. Overall, the Miller XMT 350 CC/CV delivers reliable, versatile MIG/MMA performance for professionals seeking precision and durability in a single, portable unit.

Additionally, the XMT 350 supports a wide range of wire feeders, including the Miller 4‑inch and 6‑inch feeders, and is compatible with standard 1.25 mm and 1.6 mm MIG wires. The machine’s intelligent arc‑sensing algorithm automatically adjusts the output to maintain optimal arc stability, even when switching between 1.25 mm and 1.6 mm wires. Users can also connect the built‑in USB port to the Miller XMT 350 app for remote monitoring and firmware updates, ensuring the unit stays current with the latest software improvements. The unit’s modular design allows easy replacement of the power module, enabling upgrades to higher‑output models without replacing the entire system. All these features combine to make the XMT 350 a versatile, future‑proof solution for demanding welding environments.

The ergonomic handle is designed with a non‑slip grip and a quick‑release clamp, allowing welders to change wires or adjust the torch angle without stopping the machine. The integrated cooling fan keeps the internal temperature below 80 °C during prolonged use, preventing thermal shutdown. The XMT 350’s compliance with the latest safety standards, including IEC 60204‑1 and ISO 13849‑1, guarantees safe operation in industrial settings. Finally, the unit’s low power consumption—only 2.5 kW at 50 % load—helps reduce energy costs while maintaining high welding quality.

TIG (GTAW) Capability

The Miller XMT 350 CC/CV delivers robust TIG (GTAW) performance with a dual‑mode AC/DC output, allowing 208/230 V AC or 460 V DC operation. The inverter’s precise current regulation supports 0.5 mm to 25 mm carbon steel, stainless steel, and aluminum, with adjustable voltage and polarity for each material. The built‑in pulse‑control feature offers fine‑tuned pulse frequency and amplitude, enabling deep penetration and smooth weld beads on thin sheets and thick plates alike. The 2‑port design permits simultaneous TIG and MIG/MMA operation, while the 2‑way selector switch lets users toggle between AC and DC modes without interrupting the arc. The machine’s full‑color LCD, rotary encoder, and programmable memory provide an intuitive interface for setting voltage, current, and polarity, ensuring consistent weld quality. Safety features include over‑current protection, short‑circuit detection, and a chassis that meets UL and CE standards. The compact footprint (12.5 × 9.5 × 4.5 in) and lightweight construction (≈15 lb) make the XMT 350 portable for field and shop use. The 100 % duty cycle allows continuous TIG operation during demanding tasks. The XMT 350’s intelligent arc‑sensing algorithm automatically adjusts output to maintain optimal arc stability, even when switching between 1.25 mm and 1.6 mm wires. Users can connect the built‑in USB port to the Miller XMT 350 app for remote monitoring and firmware updates, ensuring the unit stays current with the latest software improvements. The ergonomic handle features a non‑slip grip and quick‑release clamp, allowing wire changes without stopping the machine. The integrated cooling fan keeps internal temperature below 80 °C during prolonged use, preventing thermal shutdown. Compliance with IEC 60204‑1 and ISO 13849‑1 guarantees safe operation in industrial settings. Finally, the unit’s low power consumption—only 2.5 kW at 50 % load—helps reduce energy costs while maintaining high welding quality.

Automatic Mode (Auto-Line)

In Auto‑Line mode the Miller XMT 350 CC/CV automatically selects the optimal welding parameters for the chosen material, thickness, and electrode type. The integrated Auto‑Line algorithm scans the input data, calculates the required voltage, current, and polarity, and applies the settings with a single button press. This feature is especially useful for rapid job‑site changes, as it eliminates manual tuning and reduces setup time. The Auto‑Line interface displays the selected parameters on the 2‑inch color LCD, and the rotary encoder allows fine adjustments if needed. The system supports a wide range of consumables, including 0.8 mm to 2.0 mm MIG wire, 1.0 mm to 3.0 mm MMA electrode, and 0.5 mm to 1.6 mm TIG wire. Auto‑Line also includes a “Quick‑Set” memory for frequently used configurations, enabling the operator to switch between preset modes with a single press. The automatic mode is fully compliant with the Miller XMT 350’s safety standards, featuring over‑current protection, short‑circuit detection, and an integrated cooling fan that keeps the unit at safe operating temperatures. The Auto‑Line function is accessible via the machine’s main menu, and the system’s firmware can be updated through the USB port to incorporate new material libraries. This mode is ideal for production lines where consistency and speed are paramount, allowing welders to focus on quality rather than parameter selection. Auto‑Line also offers automatic wire feed speed adjustment, arc‑length sensing, and pulse‑control tuning for thin‑sheet applications, ensuring stable arcs even when the workpiece moves. The feature’s intuitive design reduces operator fatigue and improves weld consistency across multiple jobs, making it a valuable tool for both shop floor and field welding tasks. Additionally, the Auto‑Line mode logs each job’s parameters to the internal memory, enabling traceability and repeatability for quality assurance audits.

Manual Mode (FieldPro)

The FieldPro manual mode on the Miller XMT 350 CC/CV gives operators full control over welding parameters, ideal for complex or custom jobs. Operators can manually set voltage, current, polarity, and wire feed speed using the rotary encoder and push‑buttons on the front panel. The 2‑inch color display shows real‑time values, and the system supports both CC and CV modes for MIG/MMA and TIG processes. In CC mode, the machine maintains a constant current while the voltage adjusts automatically; in CV mode, the voltage is fixed and the current varies to keep the arc stable. The FieldPro interface allows quick toggling between these modes, and the user can lock settings to prevent accidental changes during a weld. Wire feed speed can be set from 0 to 200 mm/min, and the machine’s built‑in cooling system ensures consistent performance even during prolonged use. Safety features such as over‑current protection, short‑circuit detection, and an integrated cooling fan are active in manual mode. The FieldPro mode also supports a “Quick‑Set” memory, allowing the operator to store and recall custom parameter sets for repeated use. The manual mode is fully compliant with UL and CE standards, and the XMT 350’s compact footprint (12.5 × 9.5 × 4.5 in) and lightweight design (15 lb) make it portable for field applications. Users can update firmware via USB to add new material libraries or improve performance. Overall, FieldPro provides welders with the flexibility and precision required for demanding projects while maintaining the reliability and safety that Miller is known for. Its intuitive controls make it a favorite pro; (rec.)!!!!

Pulse and Constant Current Settings

The Miller XMT 350 CC/CV offers pulse and constant‑current (CC) modes for versatile welding. Pulse mode delivers frequencies from 10 Hz to 120 Hz, with pulse widths 0.5 %–50 % of the cycle, enabling fine control over penetration and bead shape. Pulse amplitude ranges from 10 % to 100 % of the set CC value. The CC mode provides a stable current up to 70 A AC or 60 A DC, with 0.1 % resolution. The controller auto‑adjusts voltage to keep current steady. Both modes are selectable via the rotary encoder and displayed on the 2‑inch screen, with presets for repeatable results.

Constant‑current mode delivers up to 70 A AC or 60 A DC, with 0.1 % resolution. The controller auto‑adjusts voltage to keep current steady, ideal for MIG, TIG, and stick welding. Pulse‑on mode offers brief current spikes for deeper penetration while limiting heat input. modes are selectable via the front panel and displayed on the 2‑inch screen.

Both pulse and CC modes are selectable via the front‑panel encoder and 2‑inch display. The firmware auto‑selects voltage range (AC or DC) based on polarity. Safety interlocks prevent accidental mode changes, and protection shuts down the arc if the set current exceeds the maximum rating. The XMT 350’s design (12.5 × 9.5 × 4.5 in) and construction (15 lb) make it ideal for mobile work. Whether you need a high‑precision pulse for thin aluminum or a robust CC mode for heavy‑stock MIG, the XMT 350 delivers reliable performance with intuitive controls and real‑time feedback. Settings adjustable.!