Why does fiber cut cheaper

Indeed, the differences in the cost of electricity for CO2 and fiber lasers can be multiple. Of course, this applies to sheet metal cutting up to 3-4 mm, but beyond this limit, contrary to what representatives of other brands claim, a fiber laser is also much more economical in terms of electricity consumption.
For thin sheets, the CO2 laser speed is achieved with the fiber laser at half the output power of the CO2 laser.
CO2 lasers actually have an efficiency of about 10%, but this only applies to the energy efficiency of the source and has nothing to do with how much power the laser consumes during operation as a whole machine.

Suppose we are considering a 4kW CO2 laser. at 10% efficiency, 40kW is required to power it. The laser is powered by RF electricity. and since the high-frequency power supply also has limited efficiency, the resonator itself actually consumes about 50kW of energy.
Another energy-consuming element of the CO2 laser is the turbine that accelerates the gas mixture to enormous speeds. The power of this turbine is about 8kW.
But it is not everything. If we put 58 kw and we have 4kW at the output, then 54kW must be collected in the form of heat. The cooler takes about half of what it is able to receive from the cooled system, so it will be approx. 29kW.
So we already have 83kW, and there is also a dedusting system of at least 3kW, a vacuum pump, etc.
These calculations give a total of 86kW not counting the laser axis drives. Let’s say let it be 90kW. And exactly this power value is given in the instructions for the 4kW laser that we have. For comparison, our other 2.6kW laser gives 60kW of power. So it’s roughly proportional.

And now for comparison the fiber laser:
2kW of IPG laser output power requires exactly 6kW of power.
So, about 4kW is left to dissipate. As the source in question can work at a higher temperature than CO2, to disperse these 4kW, a 1.5kW cooler with a refrigerator is enough, which will give us a total of 7.5kW. After adding the dust collector and accessories, it will be about 12kW.
So even when comparing not only the resonator itself, but the whole machine, because this is what the user is interested in, the advantage of the fiber laser is at least 7 times.

However, for larger thicknesses, to make sense, you should compare a CO2 laser and a fiber laser with the same power. So let’s count again 4kW laser takes 12kW + 3kW refrigerator gives 15kW + dust collector and drives give 19kW, so 4 times less.

As for the cutting speed, the basic rule is that there is no type or thickness of sheet metal at which a CO2 laser would be faster than a fiber laser of the same power.
This is because the light from the fiber laser can be focused more, i.e. obtain a higher concentration of energy, and the light from the fiber laser is better absorbed by metals than CO2 laser light. Often, manufacturers of CO2 lasers compare a 4kW CO2 laser to a 2kW fiber laser for thicker sheets, and in this case it will actually be in favor of CO2, but this comparison does not make sense.

The truth is, CO2 and fiber laser manufacturers have a specific interest in discouraging their customers from opting for fiber lasers. Simply, most of them produce the CO2 source themselves, and since the price of the source is about half the price of the laser, half of the profit on the laser comes from the profit on the source. If someone orders a laser with a fiber resonator, which they will have to order from IPG, the producer will earn half of the laser and IPG’s half. For this reason, to achieve a comparable profit, the laser manufacturer has to produce 2 fiber lasers instead of one CO2. Large companies that have so far produced CO2 lasers must of course also offer fiber lasers so that their competitors do not suspect that they are not developing, but this is not the best business for them.

A fiber laser also uses less cutting gas. Due to the behavior of light during focusing, the shorter the wavelength, the more the beam can be focused. Due to the fact that the wavelength of fiber laser light is ten times shorter than that of CO2 lasers, the possibility of focusing increases significantly, and this allows the use of smaller nozzle diameters than in the case of a CO2 laser, which directly reduces gas consumption.