Lorch V30 AC/DC, used TIG welder

The Lorch V30 AC/DC is an inverter TIG power source for alternating and direct current, with an MMA mode. In TIG you set from 3 A to 300 A, in MMA from 10 A to 250 A, and the duty cycle is 300 A at 50% and 200 A at 100% at a temperature of 40 °C. The supply is 3 x 400 V with a 16 A slow blow fuse.

What this machine is for

With alternating current you weld aluminium and its alloys, with direct current high alloy steels, acid resistant steels and titanium. The lower limit of 3 A gives control over material thinner than 0.5 mm, where a plain power source burns through the sheet, and the upper 300 A pulls thicker vessel walls. Under continuous load the machine holds 200 A, so you make long circumferential joints with no breaks.

The maker aimed this model at plants that make critical joints: process equipment, pressure vessels, heat exchangers, pipework in the food industry, repairs and production of aluminium parts in transport, among them trailers and fuel tanks, and precise assembly work on special steels and on titanium. Repeatable parameters come from work in line with WPS welding procedure specifications and with the requirements of the ISO 3834 standard.

TIG is welding with an arc that burns between a non consumable tungsten electrode and the material, under argon, with filler fed by hand or with no filler at all. The process is slow, but it gives full control over the pool and a clean weld with no spatter, which is why it goes where the joint is sent for testing and has to be tight. Alternating current adds a cleaning phase that breaks the layer of aluminium oxide, because without it the arc will not fuse into the material. Direct current runs acid resistant steels and titanium, where a narrow heat affected zone counts and where shielding is needed from the root side as well.

Digital control shortens the time it takes to reach the parameter. Instead of a plain linear characteristic the machine uses ready welding curves, reacts to changes in the arc and sorts out the ignition phase and the current rise on its own. For the welder that means less risk of tungsten inclusions and of lack of penetration in hard positions, and for the plant a repeatable result when the operator changes.

The third group of tasks is the covered electrode. The MMA mode from 10 A to 250 A helps with service and repair work, where a gas shield will not stay over the pool, for example in wind or in a trench.

Features and equipment

• SmartBase: a base of welding curves in the controller matches the supply parameters to the method and the material, leads the ignition phase, the current rise and the arc stabilisation, so it shortens the setting up of the machine.
• TipTronic: a memory for 100 welding jobs with the full cycle, from the gas pre flow time, through the pulse, to the current down slope. You call the programs from the panel or with the buttons in the torch handle.
• Alternating current frequency up to 200 Hz: a higher frequency narrows the arc and gives a narrow, deep penetration and exact guiding along the edges of sheets of different thickness.
• AC balance control: you set the ratio between the cleaning phase, which breaks the layer of aluminium oxides, and the fusion phase, which protects the tungsten electrode against heavy wear.
• Fast pulse: it lowers the heat put into the material, so thin walled parts distort less and hot cracks appear less often in the heat affected zone.
• MACCS cooling system: the air ducts are parted from the control boards, so welding dust does not settle on the electronics.
• Housing that takes a fall from up to 60 cm without loss of function, with transport handles.
• MMA mode from 10 A to 250 A: the covered electrode for repairs and rebuilding.
• Integrated liquid cooler in the version with the set: it takes the heat from the torch during long work at high current, so the handle stays cool and the electrode and the gas nozzle work longer.
• The full TIG cycle in every job: gas pre flow time, start current, up slope, working current, down slope and gas post flow, that is everything that decides how the crater is closed and how the cooling weld is shielded.
• Up and Down buttons in the torch handle: you change the program at the part, without going back to the panel, which shortens the changeover on parts with different wall thickness.

Technical data

What to watch out for

The machine needs a 3 x 400 V connection with a 16 A slow blow fuse. A 50% duty cycle at 300 A means five minutes of welding in a ten minute window, work with no limit starts at 200 A, and the data refer to an ambient temperature of 40 °C. You will use the 3 A current only with a well prepared electrode and clean material, because at such energy every trace of dirt shows in the weld.

For work on aluminium count on the accessories: a tungsten electrode for alternating current, a well matched nozzle and gas shield, and argon of the right purity. A high AC frequency narrows the arc, but it also wears the electrode faster, so you set the balance with care and not at the maximum of the cleaning phase. On thin sheet below 0.5 mm you need firm support of the part and a backing bar, otherwise the material will run away in spite of the 3 A current.

The shop catalogue data give liquid cooling, while the documentation describes the cooler as part of the set, so before you buy confirm whether it comes with a liquid cooled torch. When you work with a liquid cooled torch you check the fluid level and the flow before the first arc. Program control from the handle works only with a torch that has Up and Down buttons.

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