HBS ARC 800 with a PMH-12 gun is an industrial stud welder working by the drawn arc method. A transformer rectifier system delivers a current of 800 A at a working voltage of 30 V, and you dose the energy with a time from 5 to 1000 ms. The supply is 3 x 400 V with a slow blow 35 A fuse, the housing has protection class IP23.
What this machine is for
This is equipment for permanently welding in threaded studs from M3 to M12 and plain pins of 2 to 10 mm diameter into material thicker than 2 mm. It goes to heavy steel structures, to shipyards and power generation when fixing thermal insulation studs and assembly pins, to bodies, frames and machine housings, and also to series production, where a short preparation time and repeatability count.
The process needs no electrodes and no wire. After the trigger is pressed an electromagnet lifts the stud, a pilot arc strikes, and right after it the main arc at 800 A. It melts the face of the stud and a thin layer of sheet under it. After the set milliseconds have counted down the current breaks off, and the spring in the gun drives the pin into the hot pool. The joint sets across the whole section, so in a break test it is usually the stud itself that fails, not the weld.
The machine handles three variants of the process. With a ceramic ferrule you work on thicker studs and sheet in non alloy steel: the ceramic shields the heat zone from oxygen, and when the stud is pressed in it acts as a mould that lays an even fillet around the pin. Once it has cooled you break the single use ferrule off with a hammer. Under gas shielding, at a flow from 8 to 16 l/min, you give up the ceramic, you get less spatter and a cleaner profile around the joint, which is usually chosen on stainless steel. The short cycle, that is a time below 100 ms, serves for welding a stud quickly on thinner base material.
You do not adjust the current steplessly. The machine works at full power, and you change the portion of heat only with the discharge time. The manual gives reference points for non alloy steel: about 45 ms for an M6 thread, 80 ms for M8 and about 180 ms for M12.
Stud welding differs from welding in that the whole joint is made in one short discharge, across the whole section of the pin at once. There is no bead here, no filler and no torch movement, but there is a very short time and a very high current. That is why three things decide the result: the discharge time, the gun lift that sets the arc length and the force of the spring that drives the pin into the pool. You pick the settings once, on samples, and then repeat them over the whole run.
The transformer rectifier build gives an advantage over an inverter here. A heavy transformer coupled with a semiconductor switching system takes pulses of 800 A repeated at short intervals without trouble, it stands up to dirt and mains swings, and diagnostics comes down to simple components. The price is a high machine weight and no stepless current adjustment.
Features and equipment
- A transformer rectifier build: a large current reserve and resistance to dust and mains swings, greater than in inverter systems.
- Digital time setting from 5 to 1000 ms: the only, but precise way of dosing the energy, matched to the stud diameter and the type of coating.
- Microprocessor control with a self test after the start and error codes: on overheating or a fault the system blocks welding.
- Five diodes on the panel: ready state, tripped protection and lock, the electromagnet switching on, the signal from the trigger and proper contact of the stud with the sheet.
- PMH-12 gun with a control and a power cable: adjustment of the lift, that is the arc length, and of the spring force, which decides the dynamics of driving the pin into the pool.
- A panel with gas distribution: a multi pin control connector, strong current sockets that limit voltage drops at 800 A and gas ports with a solenoid valve dosing the shielding to the head.
- A gas test from the panel: you fill the hose with gas before the first weld, so the first pool is shielded.
- A gun lift test: you check the electromechanics and the force of the coil that lifts the stud, without striking an arc, which helps to spot wear of the gun or worn contacts.
- Fan cooling switched on by temperature: it runs when it has to, so less dust gets inside while the machine rests.
- Three variants of the process: with a ceramic ferrule, under gas shielding at a flow from 8 to 16 l/min and a short cycle below 100 ms on thinner base material.
- A built in mains filter: it puts the supply in order when working on a building site and in installations with changing voltage quality.
Technical data
| Model | HBS ARC 800, stud welder |
|---|---|
| Method | drawn arc, ARC stud welding |
| Welding current | 800 A |
| Weld time | from 5 to 1000 ms, digital adjustment |
| Threaded studs | from M3 to M12 |
| Plain parts | diameter from 2 to 10 mm |
| Minimum material thickness | over 2 mm |
| Working voltage | 30 V |
| Open circuit voltage | 70 V |
| Supply | 3 x 400 V, 50 or 60 Hz |
| Fuse | 35 A slow blow |
| Duty cycle | 5% |
| Shielding gas flow | from 8 to 16 l/min |
| Cooling | fan controlled by temperature |
| Protection class | IP23, working class S |
| Gun in the set | PMH-12 |
What you get
- HBS ARC 800 welder
- PMH-12 gun with a control and a power cable, with lift and spring force adjustment
- cabling and earth clamps
What to watch out for
The supply is 3 x 400 V at 50 or 60 Hz, a slow blow 35 A fuse, a 5% duty cycle. The working voltage is 30 V, the open circuit voltage 70 V. Cooling is by a fan switched on by temperature, the housing has protection class IP23 and working class S, so the machine takes a building site but not flooding.
At a current of 800 A a strong magnetic field arises, which can deflect the arc. It shows as one sided melting of the joint, and the only working remedy is a symmetrical placing of the earth clamps around the welding point, above all on edges and bends. The surface must be free of rust, paint and grease, and hard rolling scale has to be ground off, otherwise the arc burns unsteadily and pores form in the joint.
For sheet of about 1 mm this machine does not suit, because the energy is too high. For thin walled housings and body parts capacitor machines are provided. You check the quality of the settings with a break test: on a correct weld the pin breaks under the thread or tears out a piece of material, and does not come away along the smooth surface of the face.
This unit is sold
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