Three options at one current level
A fabrication workshop that welds sections and sheet from 3 to 20 mm needs a MIG/MAG machine of 400 A with a separate wire feeder and liquid cooling. At this level the choice comes down to three options. Each has a different price on the invoice and a different account after three years.
The figures in the table are indicative and net, for a set with a wire feeder, an interconnection cable 3 to 5 m long, a torch and an earth cable. A specific quote can differ by more than ten percent either way.
| Option at 400 A | Net price, indicative | Duty cycle declared by the manufacturer | Care after the purchase |
|---|---|---|---|
| Used premium (Migatronic, Fronius, Kemppi) | 22,000 to 28,000 PLN | 400 A at 60 to 100 percent | first year of the service package in the price, replacement machine for the time of repair |
| New, Spartus or Magnum class | 12,000 to 18,000 PLN | 400 A at 35 to 60 percent | 24 months of manufacturer warranty |
| New premium | 45,000 to 70,000 PLN | 400 A at 60 to 100 percent | 24 to 36 months of manufacturer warranty |
Duty cycle: compare it at one current
The duty cycle is given for a period of 10 minutes at an ambient temperature of 40 degrees Celsius, in line with EN 60974-1. 60 percent at 400 A means 6 minutes of arc and 4 minutes of cooling in every period.
A comparison makes sense only when both figures refer to the same current and the same conditions. Putting 400 A from one data sheet next to 320 A from another says nothing. Set the current at which you really work, and ask for the duty cycle at that current, at 40 degrees ambient and with the supply voltage within the tolerance from the rating plate.
How many metres of weld that is
Take one working point: a fillet weld a5, wire 1.2 mm, current 280 A. A metre of such a weld is roughly 2 to 3 minutes of pure arc. A machine that has 100 percent at 280 A lays that metre and starts the next one. A machine that has 60 percent at 280 A stops after 6 minutes and cools for 4 minutes, so it loses about two metres in every 10 metres.
With one welder per machine the difference shows in metres per shift, not in a table. On thick parts and long runs the duty cycle stops being a data sheet parameter and becomes a production schedule.
Where cheaper machines lose current
The current on the rating plate is often measured at a supply of 400 V and a temperature of 20 degrees. At 380 V, with a long extension lead and 30 degrees in the hall, the machine drops lower. Ask for three points of the duty cycle, at 40, 60 and 100 percent; if the data sheet gives only one, ask for the rest in writing.
The second thing is the wire feeder. Four drive rolls and a metal housing keep the wire steady at 1.2 mm and with a long cable. A feeder with two rolls slips more often with hard cored wire and needs the pressure corrected, although this depends on the model.
What a day of downtime really costs
A workshop rate of 120 to 200 PLN net per hour of a station is revenue, not the cost of downtime. When the machine stands still you do not lose that revenue in full, because you then carry no cost of consumables, gas and energy, and part of the work you catch up later or at a second station. You lose the contribution margin and you add extra costs.
The account looks like this: the cost of a day of downtime equals the lost contribution margin plus extra costs, minus what you catch up elsewhere. Put in your own figures, and below are the assumptions taken in this article.
- Contribution margin of a station: 60 PLN per hour of arc, after consumables, gas, energy and the pay of the welder.
- Arc time: 6 hours a day, which gives 360 PLN of margin a day.
- Half of the delayed work you catch up at a second station or in overtime, so the lost margin is 180 PLN.
- Extra costs of a day of downtime: overtime premium, moving people around, a courier for a part, sometimes a penalty for a deadline. We assume 120 PLN.
- Together 300 PLN for a day of downtime without a replacement machine.
- With a replacement machine provided for the time of repair only the changeover and the drive are left, which is 100 PLN a day.
You can see from this why what counts is not the failure rate itself, but the time to clear the fault and whether you have anything to work with meanwhile. A machine for which the service workshop has the part on the shelf and arrives within 48 hours is cheaper than a machine that has to be sent to the importer for three weeks. That is why in our service package we provide a replacement machine for the time of repair: that item lowers the cost of downtime from 300 PLN to 100 PLN a day.
Parts, consumables and what you use up every month
The torch, contact tips, nozzles, liner and rolls are a cost that does not depend on whether the machine is new. A workshop welding on one shift spends roughly 150 to 400 PLN net a month on this. This item looks the same in all three options, so it is not in the comparison below.
The difference starts with machine parts. Do not take any number of years here on trust, ours included. Ask directly for three catalogue numbers: the power module, the control board and the feeder motor, for the declared period of their availability in writing and for how many pieces are in the country. If the answer is that they will be ordered if needed, put two weeks of downtime into the account and price them with the model from the previous section.
Who answers for the machine after the purchase
A new machine has a manufacturer warranty, usually 24 months, sometimes 36 after registration. With a used one there is no commercial warranty, but the price includes the first year of the basic service package. You buy further years, and then repairs come out cheaper, a periodic inspection is added and you get priority in the queue. The practical difference is that with a used machine you talk to the service workshop that took this machine apart before the sale.
We check every unit in our service workshop against the current standards. In the product card we describe the load test, the state of the wire feeder, the cooling unit and the interconnection cable, and what has been replaced. You get the inspection report with the extended service package. We describe the method in the service section.
With a new machine, also work out what the paperwork is really worth, because the terms of a 5-year warranty on a welder (guide in Polish) include exclusions you need to ask about before buying.
Scenario A: 6 hours of arc a day, current up to 400 A
The same workshop, three machines, a horizon of 36 months. The assumptions written out plainly: the cost of a day of downtime 300 PLN without a replacement machine and 100 PLN with one, an inspection once a year, resale value estimated carefully. The number of days of downtime is an assumption as well, not a measurement: 4 days for the used premium, 5 days for the new budget machine working close to the limit of its duty cycle, 2 days for the new premium under warranty.
| Item, 36 months | Used premium | New Spartus or Magnum | New premium |
|---|---|---|---|
| Net purchase | 25,000 PLN | 15,000 PLN | 55,000 PLN |
| Preparation: start up, trolley, earth cable, training | 1,200 PLN | 800 PLN | 1,200 PLN |
| Service: 3 periodic inspections | 1,200 PLN | 1,200 PLN | 1,800 PLN |
| Parts and repairs outside the package and outside the warranty | 2,000 PLN | 3,000 PLN | 0 PLN |
| Downtime | 4 days x 100 PLN = 400 PLN | 5 days x 300 PLN = 1,500 PLN | 2 days x 300 PLN = 600 PLN |
| Resale value after 3 years | minus 15,000 PLN | minus 4,000 PLN | minus 32,000 PLN |
| Total, net cost of 3 years | 14,800 PLN | 17,500 PLN | 26,600 PLN |
On these assumptions the used premium comes out cheapest, the new budget machine dearer by 2,700 PLN, and the new premium the most expensive, because its purchase price is the highest despite the best resale value. If a day of downtime were priced with revenue of 1,200 PLN, the same three totals would grow to 19,200, 22,000 and 28,400 PLN, and the differences between the columns would largely be the work of one assumption. That is why we price downtime with the contribution margin and take the replacement machine into account.
Note that after this change downtime stops being the largest item of the account. The difference between the used premium and the new budget machine is now made by the loss of value and the cost of repairs, not by days of standstill. Downtime comes back into play only when you have no spare station and you work two shifts.
Scenario B: 2 hours of arc a day, current up to 250 A
The same workshop a year later, smaller orders, occasional work. The contribution margin is the same, 60 PLN per hour of arc, but at 2 hours a day that gives 120 PLN of margin a day. Half of it you catch up, the extra costs are lower, so we price a day of downtime at 120 PLN. We assume 1 day of downtime in each option, because at such a load the machine does not run close to the limit of its duty cycle.
The subject of the comparison changes as well. At a current up to 250 A you do not buy a 400 A machine, you buy a machine matched to the work. That is why the cheaper column holds a new 250 A machine for 6,000 PLN, not a 400 A machine for 15,000 PLN.
| Item, 36 months | New 250 A machine, budget class | Used premium 400 A |
|---|---|---|
| Net purchase | 6,000 PLN | 25,000 PLN |
| Preparation: start up, trolley, earth cable, training | 500 PLN | 1,200 PLN |
| Service: 3 periodic inspections | 900 PLN | 1,200 PLN |
| Parts and repairs outside the package and outside the warranty | 1,200 PLN | 1,200 PLN |
| Downtime | 1 day x 120 PLN = 120 PLN | 1 day x 120 PLN = 120 PLN |
| Resale value after 3 years | minus 2,000 PLN | minus 17,000 PLN |
| Total, net cost of 3 years | 6,720 PLN | 11,720 PLN |
Here the cheaper machine wins, and clearly so, by 5,000 PLN. Not because it is better, but because at 2 hours of arc a day and a current up to 250 A the reserve of power and the duty cycle have nothing to pay back, and the surplus of the purchase price stays in the machine for three years. The conclusion from both scenarios is one: the result is decided by the hours of arc, the working current and whether you have a spare station, not by the class of the machine itself.
When a used premium machine wins
A used premium machine makes sense when you weld several hours every day and need a current above 300 A. Machines of this class are designed for industrial work over many years, but how much is left in a specific unit is told by its mileage and the result of the check, not by its age alone. On top of that comes the support of a service workshop that knows the diagram and has access to parts.
The second case is welding aluminium and thin stainless steel, where the resolution of the settings and the library of synergic programs count. Pulse and double pulse in cheaper machines are sometimes simplified to a single slider, which on 1.5 mm sheet ends in burn through or a cold lap.
The third case is a workshop that already has one machine of that brand. Shared torches, rolls, cables and the same interface shorten the changeover and simplify the parts store.
When a new cheaper machine is the better choice
Scenario B above is the typical case: occasional work, up to 2 hours of arc a day, current up to 250 A. Then the duty cycle is not the bottleneck, and 24 months of manufacturer warranty and a low price of spare parts are worth more than a reserve of power.
The second situation is a standby station or mobile assembly work, where the machine travels in a van, stands in dust and gets damaged mechanically. There is no point in exposing a machine for 50,000 PLN to that. See what we have in the category new MIG/MAG.
The third situation is a workshop that is only starting and does not know its own workload yet. A cheaper machine for the first year is a sensible way to find out. An alternative is rental for a few months, because then you pay for the actual use and you do not freeze cash.
Four questions before the decision
- How many hours of arc a day you plan and at what current: that gives the required duty cycle at that one current.
- What your contribution margin per hour of arc is and how much of the delayed work you catch up at a second station: that gives the cost of a day of downtime.
- Who will repair the machine within 48 hours, whether they have the part on site and whether they will provide a replacement machine.
- What you get in the set: wire feeder, torch, earth cable, cooling unit, trolley, interconnection cable and its length.
Answers to these four questions settle the choice faster than a comparison of data sheets. If you have an old machine to hand over, we value it in our buy back and deduct it from the new purchase.
Let us count it on your figures
Give us the hours of arc, the material thicknesses, the working current and the contribution margin of the station, and we will prepare a comparison of two or three specific machines from stock, together with the three year cost counted with the same model. Call us or look straight into the category used MIG/MAG, where every machine shows a list of the set.