The Insquare takes care of daily maximum performance.

The TIG Inverter welding units offer professional performance all along the line. Five models, 320 A to 600 A, for DC and AC current fulfil even highest demands for industrial applications. Professionals are enthusiastic about the perfect technique and the easy operation of the Merkle Insquare welding units.

  • IGBT inverter power sources.
  • 3-phase inverter with low primary current.
  • Stable arc in AC over the full range due to square wave or noise reduced wave.
  • Continous setting of the welding frequency in AC.
  • MMA/stick electrode welding.
  • Perfectly smoothed DC gives outstanding welding characteristics in TIG and electrode welding.
  • DC high frequency pulse for concentrated arc (see page 6).
  • Perfect arc ignition over the whole range due to separate ignition circuit.
  • A minimum of radiation caused by the HF-ignition unit.
  • Efficient cleaning in AC.
  • Special filters mounted to avoid radiation.

Multitude of control functions

  • TIG welding process:
    TIG DC minus, TIG DC plus*
    TIG DC minus with start impulse*
    TIG AC ”noice reduced“*
    TIG AC ”square wave“*
    TIG AC ”sinusodial“*.
  • MMA/Electrode welding process:
    Electrode minus, electrode plus*
    Electrode ”sinus“*
    Electrode ”square wave“*.
  • 20 programmable jobs.
  • 2 welding currents separately adjustable;
    in 4-stroke recallable by a short touch on the
    torch trigger or using a welding torch with
    two triggers.
  • Adjustable parameters: gas pre-flow and gas post-flow time,
    start and fi nal current, timer for current up and down slope.
  • Parameter pre-selection by 2 switches.
  • 2 large LED-displays with pre-indication and Hold function for
    current, voltage, time and frequency.
  • Pulse device and spot welding.
  • High frequency pulsation up to 5 kHz.
  • Current remote control with potentiometer at the torch (option).
  • High frequency (HF) or lift arc ignition.
  • 2-stroke, 4-stroke, 4-stroke with 2 currents.
  • AC-frequency setting: 50–200 Hz*.
  • AC-balance: continuous setting of the plus/minus from
    9 % to 91 %*.
  • Hand-, torch or foot remote control (optional).

Merkle TIG welding torches with Quick TIG System

  • Only few spare parts.
  • Torch cap and back cap form one single part.
  • Double button torch switch.
  • Torch with integrated potentiometer (option).
  • High-flexible torch lead with partial leather protection.
  • Ball joint at the handle.

Generous handling with highest comfort!

The display of the Merkle Insquare series has been designed to the like of the real professionals.

Well-arranged operation panel, digital display and the easy adjustment of all welding parameters provide highest functionality and safety in the daily work. And the new, lockable glass front of the models Insquare W 321 and W 421 offer even more protection of unintentional changing of the welding parameters.

Perfect welding for all applications!

The welding units are specially designed for industrial use and are optimally suitable for manual, automatic or robot operation. A PLC or a robot controls the following parameters:

  • Welding current.
  • Welding frequency (AC-mode).
  • AC balance

Hand welding

Automated welding

Robot welding

High frequency DC pulse

The machines of the series Insquare come as a standard with the high frequency DC pulse. The arc can be pulsed with a frequency up to 5 kHz. The arc characteristics provide outstanding opportunities in TIG DC welding that are not available in the normal TIG arc:

Standard TIG weld

High frequency DC pulse weld


  • Extreme arc constriction.
  • Arc similar to plasma welding.
  • Less heat input.
  • Higher welding speed.
  • Extremly stable arc.
  • Perfect for corner welds.

Technical Data