Auto-Line™ power management technology

Allows for any input voltage hookup (380–575 V) with no manual linking, providing convenience in any job setting. Ideal solution for dirty or unreliable power.

Meter calibration

Allows digital meters to be calibrated for certification.

Cooler Power Supply (CPS)

Is an integrated 120-volt dedicated-use receptacle for the Coolmate™ 3.5.


Feature operates the auxiliary cooling system only when needed, reducing noise, energy use, and airborne contaminants pulled through the cooler.

Wind Tunnel Technology™

Protects internal electrical components from airborne contaminants, extending the product life.


Power source cooling system operates only when needed, reducing noise, energy use and the amount of contaminants pulled though the machine.

Program memory

Features nine independent program memories that maintain/save your parameters.


Adjusts the length of postflow time based on the amperage setting, shielding your tungsten and eliminating the need to set the postflow time.


Provides DC arc initiation without the use of high frequency.

Blue Lightning™

High-frequency (HF) arc starter for non-contact arc initiation. Provides more consistent arc starts and greater reliability compared to traditional HF arc starters.

DC TIG Features

Exceptionally smooth and precise arc for welding exotic materials.
Pulse. Pulsing can increase puddle agitation, arc stability and travel speeds while reducing heat input and distortion. These models provide extended ranges.

DC Stick Features

DIG control allows the arc charac teristics to be changed for specific applications and electrodes. Lower the DIG setting for smooth running electrodes like E7018 and increase the DIG setting for stiffer, more penetrating electrodes like E6010.
Hot Start™ adaptive control provides positive arc starts without sticking.

What’s included

Pulsed TIG (GTAW-P)
Stick (SMAW)
Air carbon arc (CAC-A)
400: 6 mm maximum


General specification
Title Maxstar® 400
Industries Interests Precision metal fabrication
Tube mills
Pipe and tube fabrication
Tool and die
Exotic material fabrication
Pressure vessel fabrication
Material Thickness
Weldable Metals Thin to thick material.
Special alloys
Input Voltage 380–575 V
Input Phase 3-phase power
Input Hz 50 Hz
Amperage Range 3–400 A
Current Type DC
Rated Output 300 A at 32 V, 60% duty cycle
Max Open Circuit Voltage 75 VDC
Weld Output CC
Net Width 349 mm (13.75 in.)
Net Height 629 mm (24.75 in.)
Net Length 559 mm (22 in.)
Net Weight 61 kg (134 lb.)
Warranty 3 Years
Miller’s True Blue Warranty