Kemppi Kempomat 2500 is a transformer MIG/MAG welder for the workshop and lighter production. You set the current from 40 to 250 A, at a 30% duty cycle the machine gives 250 A, at 60% it gives 180 A, and in continuous work 140 A. You choose the voltage with a switch of 10 steps, and the built in two roll feeder takes spools up to 20 kg with a diameter of 300 mm.
What this machine is for
The build rests on a transformer with a rectifier circuit, without elaborate electronics. The copper winding and the mechanical contactors take dust and rough conditions, and the manufacturer allows work at a temperature from minus 20 to 40 degrees C. The machine works only on direct current and handles solid wires from 0.6 to 1.2 mm, cored wires from 0.8 to 1.2 mm and, with a certain reservation, aluminium ones from 1.0 to 1.2 mm. The settings are fully manual, without synergy, so the operator has to know how to match the voltage to the feed.
An interesting solution is the two earth sockets on the front, marked I and II. They change the hardness of the arc by connecting the earth at a different point of the choke coil. Socket I gives a harder arc, with sharper penetration, which suits thin sheet and wires from 0.6 to 1.0 mm under CO2 shielding. Socket II gives a soft arc, meant for thicker fillers and stainless materials, with visibly less side spatter. This is a mechanical control, so it cannot be knocked out of tune by accident from the panel, and the effect shows at once in the behaviour of the pool. In practice it is worth having two earth points ready and moving the plug depending on the material.
The KMW Timer module adds 2T and 4T modes and spot and cyclic welding. In spot mode the machine cuts the energy after a set time whatever the trigger is doing, so all the tack points have the same volume. Cyclic welding interleaves heating phases with pauses, which limits distortion on delicate products and protects the edges against running. The manufacturer aimed this model at mechanical workshops, at metal shops working continuously up to 140 A, at thin walled production and at sheet metal service shops. The uses listed are the spot module on thin car bodies in the automotive trade, repairs of building equipment on thicker sections at a current up to 250 A, work on acid resistant steels with a soft arc from earth socket II and welding with cored wire at a steady speed within the range from 0 to 18 m/min.
Features and equipment
- Transformer with a rectifier circuit and a current range from 40 to 250 A: a reserve of output for thicker sections, with work at a temperature from minus 20 to 40 degrees C.
- Duty cycles of 250 A at 30%, 180 A at 60% and 140 A at 100%: three points that tell you the real output of the station.
- Stepped voltage control in 10 steps: from settings around 17 V for galvanised parts to full fusion in thick walls, without the risk of surges on controllers.
- Built in two roll drive with rolls 32 mm in diameter and a wire speed from 0 to 18 m/min: steady feeding of steel and flux cored wires and, to a degree, of aluminium ones.
- Chamber for spools up to 20 kg with a diameter of 300 mm: rarer changes of material and fewer stoppages in production.
- Two DIX earth sockets, I and II: a mechanical change of the arc hardness, harder for thin sheet and wires from 0.6 to 1.0 mm in CO2, soft for thicker fillers and stainless steel.
- KMW Timer module with 2T and 4T modes: two step for short jobs, four step takes the need to hold the trigger off your hand and closes the gas flow after the end.
- Spot welding with a time setting: the feeder and the transformer cut the energy at the end of the interval, so the tack points come out the same.
- Cyclic welding: the machine interleaves heating phases with pauses itself, which limits thermal distortion and protects the edges of thin parts.
- Wire burn back time control: a potentiometer in the drive compartment sets the burn back after the rolls stop, so the wire does not bake into the contact tip and does not stay in the freezing crater.
- Cold wire feed button: you push the filler through the liner without a voltage of the order of 17 to 35 V and without opening the solenoid valve, so you do not lose gas.
- Adaptive cooling of the power source: the fan starts after 15 seconds under load and runs for as long as 10 minutes after the last arc, cooling the bridge and the transformer, and in the breaks it does not draw in dust.
- Thermal protection of the windings: once the allowed load is passed the machine blocks the process and signals it with a yellow lamp until it cools down.
- Euro torch connector: you pick the accessories from a widely available standard.
Technical data
| Manufacturer | Kemppi Oy |
|---|---|
| Model | Kempomat 2500 |
| Supply | 3 x 230 V or 3 x 400 V, 50 to 60 Hz |
| Current range | from 40 to 250 A |
| Duty cycle 30% at 40 degrees C | 250 A |
| Duty cycle 60% at 40 degrees C | 180 A |
| Duty cycle 100% at 40 degrees C | 140 A |
| Number of voltage steps | 10 |
| Wire feeder | 2 roll, from 0 to 18 m/min |
| Steel and stainless wire diameter | from 0.6 to 1.2 mm |
| Wire spool | up to 20 kg, diameter 300 mm |
| Dimensions | 930 x 440 x 860 mm |
| Weight | 80 kg |
| Torch cooling | gas |
What to watch out for
The supply is 3 x 230 V or 3 x 400 V at 50 or 60 Hz, so before you connect it check which version this unit is set to. The duty cycle at a temperature of 40 degrees C is 250 A at 30%, 180 A at 60% and 140 A at 100%, so for work without breaks you count on 140 A. Going over the load ends in a thermal cut out and a break for cooling, so it is better to plan the work for the lower value.
The torch is cooled by gas, without a liquid system, and the settings are manual, without synergy, which needs an experienced operator or a good table of parameters at the station. The drive is a two roll one, so it feeds hard steel wires surely, while soft aluminium wire is a harder material for it, especially with a longer torch. The machine weighs 80 kg and measures 930 x 440 x 860 mm, to move it you need a pallet or a truck. The rolls and the liner are matched to the diameter of the wire. The wire burn back time is set with a potentiometer in the drive compartment, so a correction after a change of feed needs the housing opened.
How we sell used machines
This unit was checked in our service workshop in Krotoszyn with measurements to PN-EN 60974-4 and a load test. The price includes the first year of the basic service package: an inspection with cleaning of the machine and a validation measurement. Further years can be added. We ship across the European Union, collection in person by appointment.
