The Kemppi FastMig X 350 is a modular MIG/MAG system built on an industrial inverter, made up of a power source, a WFX 300T wire feeder and a FastCool 10 liquid cooler. It gives 350 A at an 80% duty cycle and 330 A at 100%, on a 400 V supply. The set of modules weighs about 200 kg.
What this machine is for
This is a set for the heat loads of multi shift and automated lines. 330 A at a 100% duty cycle means work without breaks for cooling, and 350 A at 80% gives reserve for deep welds on heavy sections. The inverter holds a linear arc characteristic also when the mains voltage in the plant jumps, which matters in series production, where every bead has to come out the same.
The materials listed in the description are carbon steels, stainless steels and aluminium alloys. The X37 and X38 digital panels with a Polish menu give access to pulse and double pulse, and the memory holds the Work Pack base of synergic curves and the WiseFusion process, which shortens the arc and concentrates the heat in the axis of the groove. The buyers are heavy industry, makers of semi trailers and tanks, process engineering of pipelines and workshops that weld aluminium.
The applications listed are work on stainless steels in the chemical and food industry with pulse, welding of sections with changing geometry with the WiseFusion process, bodywork of special vehicles with double pulse, deep tack welds in wagon bogies and in cranes, pipe roots with the optional WiseRoot software and large aluminium frames, which need a constant heat reserve from the cooler. The source description also points to pressure joints and pipelines tested for penetration, for which the machine is prepared once you buy the software modules.
Features and equipment
- Inverter power source 350 A: the inverter architecture holds the current at the set level and does not pick up voltage dips when the plant mains swings.
- FastCool 10 liquid cooler: the pump forces fluid through the torch package, so the neck and the copper threads of the tip do not overheat above 300 A and there are no stops for cooling.
- Separate WFX 300T wire feeder: the drive sits in its own case controlled over the interconnection cable, with a motor and toothed pressure rolls that guide soft aluminium wires without slipping and without bending them in the teflon liner, also when the conduit adds resistance. You carry the feeder itself onto a truss or onto scaffolding, without rolling the whole set across the shop.
- X37 and X38 digital panels: two modules with a Polish menu, run from one knob, which sort the parameters into readable tabs and shorten the training of a new operator. Polish naming lowers the risk of a mistake when you copy settings from a work sheet, for example the pulse time.
- Work Pack software: a factory base of synergic curves for stainless, carbon and aluminium wires, matched to the material thickness, so you do not set parameters by trial and error and by the sound of the arc. The curves are tied to given gas mixtures, so a change of gas needs a change of program.
- WiseFusion process: the circuit actively shortens the short arc and the spray arc, the heat stays concentrated in the axis of the groove, the weld goes deeper to the root and no excess metal builds up at the sides. In return the torch has to be led exactly in the axis, because a short arc forgives less.
- Pulse: the current oscillates without a short circuit and detaches drops in a steady rhythm, so the face is smooth and the balls of spatter at the sides of the weld need no grinding.
- Double pulse: a slower modulation with a cooling phase is laid over the pulse frequency, so the face looks like a bead laid by the TIG method. Useful on thin aluminium skins, at the cost of a slightly lower deposition rate.
- Hot Start and Crater Fill: a lift of the current at the start makes cold material flow and limits cold laps, and a soft fade at the end fills the crater, so no shrinkage and no crack is left behind. The functions help on closed sections tested for deflection and on pressure pipelines, but too much lift at the start can burn through the root in a thin pipe, so you match the value to the wall thickness.
- Ready for the optional Wise and MatchLog modes: the board supports paid WiseRoot, WiseThin, WisePenetration and MatchLog keys, bought separately against the number of the main board.
- Cable package: a 5 m torch hose with thermal insulation for a 400 A load and a short interconnection cable between the source and the feeder. Large conductor cross sections limit resistance losses, so at maximum load less heat escapes into the cables.
Technical data
| Brand | Kemppi |
|---|---|
| Type | modular MIG/MAG system with pulse |
| Supply voltage | 400 V |
| Maximum welding current | 350 A |
| Current at 80% duty cycle | 350 A |
| Current at 100% duty cycle | 330 A |
| Cooling unit | FastCool 10, liquid cooling |
| Cooling given on the data sheet | gas |
| Wire feeder | WFX 300T, separate |
| Torch cable | 5 m, 400 A load |
| Software as standard | Work Pack, WiseFusion |
| Control panels | X37 and X38, Polish menu |
| Weight of the modules | about 200 kg |
| Welding current given on the data sheet | up to 400 A |
What you get
- Kemppi FastMig X 350 inverter power source with X37 and X38 panels
- WFX 300T wire feeder
- FastCool 10 liquid cooler
- torch cable 5 m for a 400 A load
- interconnection cable between the source and the feeder
What to watch out for
The data sheet gives gas cooling and current up to 400 A, and the source description gives the FastCool 10 liquid cooler and 350 A at an 80% duty cycle, so confirm both values on the module plates. The set weighs about 200 kg, for transport you need a pallet truck or a tail lift, and across the shop you move it on the trolley wheels. The 400 V supply needs a power socket. You check the cooling circuit for leaks at the torch on a regular basis and top it up with the anti corrosion fluid the maker provides for.
The interconnection cable between the source and the feeder is short, so for work a dozen or so metres away you buy a longer package, the maker offers 10 and 20 m versions. The feeder guides and rolls have to stay clean, because swarf on the contacts spoils arc stability with pulse. You blow the dust off the boards and the heat sinks, and you protect the panel cover from grinder filings. The Wise processes other than WiseFusion are paid and tied to the board number. Work with pulse is loud in the high frequencies, so hearing protection is a must here.
This unit is sold
This machine has already gone to a customer. Similar units are listed below, and if you want the same model, leave your contact details in the form and we will let you know when the next one arrives.

















