TecArc Si 401 Pro MIG Welder 230V + SWF

The TecArc Si 401 Pro MIG Welder with separate wire feeder is a powerful and versatile welding machine, built in the UK for professional fabricators and workshops. Designed for reliability and performance, the Si Pro range offers smooth, stable MIG welding on mild steel, stainless steel, and aluminium. With a separate wire feed unit, it provides greater flexibility, improved wire delivery, and easy handling perfect for medium to heavy-duty welding applications.

We know many customers like the simplicity, reliability and cost of traditional transformer MIG welders and we don't disagree. However, UK & EU regulations mean we have had to re-design our complete range. We now have the best heavy duty inverter power outputs to compete with the best German and American machines.

Engineered for durability, these industrial MIG welders feature robust construction, user-friendly controls, and precise arc characteristics, making them ideal for both production environments and custom fabrication. The TecArc Si Pro MIG welder is a cost-effective solution for welders who demand consistent results, long service life, and excellent value.

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Key Features of the TecArc Si 401 Pro MIG Welder

• Wide Amperage Range (20-400 A)

  Enables welding from thin sheet metal up to heavier fabrication work. 

• High Duty Cycle

  At 60% duty cycle, it delivers ~370 amps, which means it can weld for long periods without overheating. Great for production environments. 

• Separate Wire Feeder

  Gives flexibility: you can place the feeder nearer to the welding site, reducing wire run, improving feed reliability, and keeping the power source out of dust/grinding zones. 

• 4-Roll All-Geared Wire Drive

  Ensures smoother, stable wire feeding, especially for softer wires like aluminium. Offers better grip and fewer feeding issues. 

• Infinitely Variable Voltage & Wire Speed Controls

  Allows fine control of welding parameters, tailoring the arc to material, thickness, type of wire. More precision = less spatter + better weld quality. 

• Digital Meters & Display

  Shows set and actual values during welding; helps with repeatability, precise setup, and easier monitoring. 

• Multi-Process Welding Capability

  Supports MIG/MAG, MMA (stick), and DC Lift TIG, plus spool gun option for aluminium. Very versatile. 

• Reversible Polarity & Trigger Modes

  Includes reverse polarity for gasless wire types, selectable trigger modes (2T/4T), and adjustable burn-back. Good control and flexibility in different welding scenarios. 

• Generator & Long Extension Cable Friendly

  Auto compensation for voltage drop, built to handle less-than-perfect power supply conditions. Useful for on-site or remote work. 

• Robust Build / UK Made

  British built, rugged construction, galvanised chassis, quality components, good support/spares. Gives confidence in durability and long-term investment value. 

• Suitable for Multiple Materials

  Capable of welding mild steel, stainless steel, aluminium, duplex, Hardox etc. Useful if you work with different metals. 

• Low Spatter, Smooth Arc Start

  Makes for cleaner work, less post-weld cleaning, better finish. 

• Safety & Efficiency Features

  Includes over-/under-voltage protection, cooling, robust wiring, built-in gas controls, etc

Supplied with S44 wire feeder, spool cover, MB36-3M MIG torch, regulator, 3M intercon lead, 3M earth lead and gas hose

Dimensions 

Power source case size: 330W x 550H x 620L

Wire feeder case size: 200W x 260H x 410L + extra for castors and wire spool cover