A technical and commercial comparison of fibre laser and CO2 laser cutting - Part 1

Since the advent of commercial fibre and disk laser cutting machines, there has been a lot of controversy about the performance of these devices – particularly in comparison to their more established CO2 counterparts. In the early days, the sales staff promoting fibre technology would often declare that the new lasers would completely take over from CO2 technology very quickly – but this has not happened. Even taking into account the entrenched position of the older technology, fibre and disk lasers have not been as widely accepted as was predicted, although they have been proven to out-perform CO2 lasers in certain important areas.

This paper presents a discussion of the advantages and disadvantages of both types of cutting technology from a commercial point of view – written from the perspective of a laser cutting job shop owner trying to decide between buying a fibre or CO2 laser cutting machine.

A quantitative comparison of the two machines is surprisingly difficult – having given several talks on the subject the best analogy we can give is that it's like comparing a sports car with a family car. Fibre lasers have been the subject of a lot of job shop interest for a few of years now – but what are they and what's the big deal – and what, for that matter, is a fibre delivered disk laser? In some ways it's a bit like being back in the 80's when CO2 laser sales folk were full of high-tech jargon and the job shop owners had to sift through all the sales talk nonsense to work out what M2 meant, and whether or not it was important.

In fact, as far as a job shop manager is concerned there is no real difference between a fibre laser and a fibre delivered disk laser. The differences between them are similar to the differences between the various technology batteries you can get for your torch. As long as the torch helps you to avoid stepping in the dish of cat food during a power cut, what do you care if it runs on Lead Zinc batteries or Star Trek diLithium crystals?

So – for the remainder of this article I will use the term fibre laser to mean both fibre and disk lasers (the technical term for both is 'high brightness 1 micron lasers'). Background information CO2 laser cutting machines have been the main workhorse of the laser cutting world since the 1970's. A typical high power CO2 job shop machine has a power of 4 or 5 kW and is used to cut Stainless steel up to 15 mm thick, aluminium up to 8 mm thick, and mild steel (with oxygen assist) up to 20 mm thick and wood or plastics up to 40 mm. (These are commercially typical figures – higher power machines are available and these are not the maximum thicknesses which can be cut at 5 kW).

Fiber and disk laser technologies are a direct extension of Nd:YAG lasers – which have enjoyed a niche in the laser cutting world since the 1980's. Originally Nd;YAG lasers were used either where fine detail (eg Clock hands) needed to be cut, or where the application demanded that the laser be fed to the workpiece by an optical fibre (e.g. on an automotive production line where space is at a premium). Fibre and Disk lasers are the more efficient, more powerful big brothers of the early Nd:YAG machines.

Multikilowatt powers are available and these machines can cut thinner section (3 mm [0.12in] or less) metals considerably faster than CO2 lasers of the same power. The choice between the two types of machine from a job shop point of view is not straight forward – both machines have advantages and disadvantages. In a meeting in the UK last year, the world's leading laser cutting expert – Dr. Dirk Petring, summed up the Fibre laser situation by saying that, 'If you comparethe CO2 and fibre laser performance for thin section metal cutting, the CO2 laser is dead'. Within hours I heard a fibre laser cutting salesman misquoting this as 'The CO2 laser is dead as far as cutting is concerned – Dirk Petring sayKids Nike Cortez