Miller Millermatic 255 MIG Welder Review [ Welding Beast]

Last Updated on May 2022

Besides excellent welding skills and knowledge, the right equipment is paramount for a seamless MIG welding process. One of those tools you need to get tasks done efficiently in your workshop is a good welding machine.

The introduction of the Miller Millermatic 255 MIG welder by Miller Electric LLC is undoubtedly a timely solution for professionals looking for smaller, high-performance welders for light fabrication and manufacturing projects.

This welding beast harbors a considerable selection of technological features that make it easy to set up and use, unlike outdated equipment, which can be quite frustrating for beginners.

In this Miller Millermatic 255 review, you are going to learn why this welder is an ideal tool for reducing downtime and increasing productivity at your welding workshop.


Easy-to-use Panel

Miller Millermatic 255 comes with an intuitive 7-inch color LCD that allows for straightforward parameter selection. The display comes to life immediately when you toggle the power switch located at the right side of the panel. The ideal position of the power switch saves you from the hassles of groping for the button hidden at the back of the machine.

The font is large for easier readability, and this, coupled with simple language, effectively eliminates the need to consult your user manual from time to time. This way, you cut the setup and change over time, while increasing weld time by an incredible scale.

Above the display are backlit Pulse and Auto-Set buttons that illuminate when active, whereas the soft-key buttons below the screen help change functions depending on the screen displayed. You can use the knobs at the sides to tweak the parameters to your liking.

The display provides you with the right gas and polarity settings for your preferred welding process, enabling you to complete the set up in no time. The easy-to-interpret connection images displayed on the screen take the Millermatic’s ease-of-use a notch higher.

The screen also flags common issues and warns the operator of loose or improperly installed cables. The prompts come in understandable words and symbols, not codes that will need you to refer to the Millermatic 255 MIG user manual.

Predefined Settings with Auto-Set Elite

Millermatic 255 welder’s Auto-Set Elite feature offers you predefined parameters, so that you set up your process effortlessly and do your job right, regardless of your welding skills level.

You activate this feature by pressing the Auto-Set button, upon which the button will illuminate, and process information will appear at the bottom of the display. When operating in this mode, you should see “Auto-Set MIG” displayed at the top of the screen.

The two left buttons (under the ‘’Material & Gas’ tab) allow you to select the wire and welding gas type. Use the center button to choose the wire diameter, between 0.023 inches and 0.045 inches. You will observe the chosen diameter above the “Wire” tab on the screen.

The last two buttons on the right allow you to select the material thickness, which is displayed on the screen too.

The Auto-Set feature also gives you more control by allowing you to fine-tune the parameters to your preferred settings by tweaking the wire feed and voltage knobs on the left and right side of the panel. During this adjustment, a bullseye on the screen represents the factory default settings.

By turning off the Auto-Set, you operate your Miller Millermatic 255 in manual mode, whereby you use the right knob to adjust wire feed speed and the left knob to control the input voltage. Be sure to refer to the comprehensive parameter chart located inside the hinged door when setting your parameters manually.

Higher-quality Welds with Pulse MIG

The Millermatic 255 welder offers pulse MIG welding both in Auto-Set mode and manual operation.

“Pulse Auto-Set MIG” is displayed when using pulse mode with Auto-Set. In this operation, “Arc Length” replaces the voltage reading, and voltage continuously varies with the wire feed speed.

When pulsing with manual mode, “Pulse MIG” is displayed at the top of the screen. The mode is set up by pressing the left button at the bottom of the display and subsequently setting the wire type, gas type, and wire thickness using knobs on the panel’s sides.

Pulse MIG comes with several benefits, including little spatter, high deposition rates, less distortion and warping, and generally better weld appearance. With minimal welding spattering, the weld looks better, and the cleanup process is easier and quicker.

Millermatic 255 automatically transitions between hot setting and cooler setting to deliver the above perks during the Pulse mode. Something else about pulse MIG is that it allows you to work with a broader range of material thicknesses.

Most beginners may not be synonymous with the difference between Pulse MIG and conventional MIG welding.

In conventional MIG welding, short-circuit transfer takes place. A continuous wire electrode is fed towards the base metal through the welding gun. The wire immediately heats when it comes into contact with the metal, forming a globule in the process.

The blob pinches off at the speed of wire feeding and subsequently flows into the puddle. This process occurs rapidly and repeatedly, creating the crackling noises common in MIG welding.

Contrarily, there is no contact between the wire electrode and weld puddle in MIG pulse welding. The process is achieved with high-speed manipulation of the machine’s electrical output and is designed to be spatterless. Additionally, it comes with an added advantage of transferring less heat to the metal, thereby reducing the chances of a burn-through.

In pulse MIG welding, a globule is formed at the end of the electrode in each pulse. The current is added to the right amount to push the metal globule across the arc into the puddle. Subsequently, the current lowers during the “background current” phase, thus contributing to generally lower heat input.

It’s this cooling-off phase that makes pulsed MIG the ideal technique for welding thinner materials, coupled with lower wire feed speed and less distortion.

Portability and Convenience at their Best

The Millermatic 255 is available as an inverter power supply, a design that paves the way for the machine’s smaller size while cutting its weight by as much as 60% when compared to the Millermatic 252 model. With the smaller size, comes more room for welding.

The welder weighs about 80 pounds, so you don’t have to deal with much weight when dragging it around your workshop or loading it into a truck.

With an optional two-cylinder or one-cylinder EZ-latch running gear, moving with this machine around the job site is hassle-free. Besides, you don’t need any tools to secure the welder to the running gear. You only have to clamp them together with quick fasteners.

Disconnecting the machine from the running gear is a pretty quick procedure. You only need to loosen the latch retaining knob and rotate the latches. Following the disengagement, it becomes easier to work with your welder in more confined spaces.

The carrier back frame has holes through which you can run a safety chain to secure your cylinder in place.

The carrier comes with a sizable storage cabinet, which is ideal for storing consumables, safety gear, and other welding accessories. No more misplacing your accessories or carrying too much stuff on your hands when moving around the job site. For more information on the top rated  mobile welding storage carts [Read Our Full Review]

Millermatic 255 welder’s Auto Line technology is a flexibility and portability feature you can’t simply overlook. It allows for the hookup with any single-phase voltage supply in the range of 208V-240V, meaning that you can work virtually anywhere with your Millermatic 255, regardless of the AC power type available on the job site.

With Auto-Line technology, this welding beast does not require manual linking, meaning you won’t have to hire an electrician to link it to AC power. Just plug in the welder, and you are good to go. The technology also absorbs and smoothen voltage dips and spikes, thereby helping maintain quality arc throughout the welding process.

Power and Versatility, All in one Piece of Equipment

You can’t help but love the power and versatility that comes with Millermatic 255 MIG welder. Thanks to the rated output of 230A at a 60% duty cycle, you can handle considerably demanding projects for an extended period without worrying over excess heat generation. The machine can comfortably weld a maximum thickness of ½ inches.

This welder’s output range enables you to work with different metals, including aluminum, steel, and stainless steel. Millermatic 255 is also a multi-process welder with MIG, pulse MIG, and flux-cored welding capabilities.

This smart welder comes with the capability to save your favorite welding settings into programs, which save you the hassles of resetting your machine repeatedly. Consequently, you increase productivity and maintain consistent weld quality. The maximum number of programs you can save is four.

Saving and recalling your settings is straightforward.

In manual mode, push the “PROG” button to display the four white program tabs on the screen. The tabs appear above the first four buttons from the right.

Save the weld settings ready by pushing and holding a program button of your choice for about two seconds. The screen should display “Saved” when the program is saved successfully.

To recall your settings, press the program button to reveal the four program tabs. Once you press a button under a particular program tab, the tab will turn blue, and the saved settings will be shown.


Whereas there is no shortage of MIG welding machines, Miller Millermatic 255 welder kicks your welding experience a notch higher.

Millermatic 255 has virtually everything you could be looking for in a MIG welder, right from versatility, excellent performance, to portability. The easy-to-use smart features loaded into this machine, including the Auto-Set Elite and Program mode, play a significant role in reducing set up time, increasing productivity, and maintaining high weld quality.

The fact that you can seamlessly undertake light and considerably heavy-duty welding projects with this relatively smaller welder also makes it an ideal choice for your next MIG welder purchase.

9.3 Total Score

User Rating: 3.17 (30 votes)

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