APPLICATION FOCUS: CUTTING


SETTING UP SHOP


John Powell, technical director of Laser Expertise, on some of the key aspects to consider when buying a new cutting machine for a job shop


Since I was first approached by salesmen in 2006 with claims of a revolutionary new laser cutting technology, the fibre lasers they were talking about have become the dominant player in the material processing market. Fibre lasers provide a fast, efficient and reliable cutting solution for metals offering reduced maintenance downtime and electricity consumption, and this has led to them all but eliminating the traditional high- power CO2


but they can’t be used to cut non-metals such as wood or plastic. This is because the light generated by fibre lasers passes straight through most plastics and wooden products without heating them up enough to create a cut. Although CO2


lasers can cut -based competition. In the UK nearly everyone has


switched over to fibre lasers. In my own firm, the last two lasers we bought were fibre, and the next one will be a fibre as well. We only have one CO2


laser left,


which we’ll probably replace with a fibre laser as it reaches the end of its life. I’ve also heard that nearly all the job shops in America and Europe have switched to fibre lasers, and this trend towards fibre lasers can also be seen in the literature on the subject: While only a tiny section of my 2008 LIA Guide to Laser Cutting discussed fibre lasers, around half of the most recent version of the book – The LIA Guide to High Power Laser Cutting (2017) is devoted to the technology.


Power isn’t everything Fibre lasers can be used to process all the metals that job shops are required to cut,


42 LASER SYSTEMS EUROPE AUTUMN 2019


both non-metals and metals, fibre lasers are often more than twice as fast at cutting metal at the sub-3mm thicknesses that job shops usually work with (see table 1). This, in addition to the fact that metals make up around 95 per cent of laser cutting job shop work, means that whether you’re a newcomer or an established job shop looking to buy some new kit, a fibre laser is the way to go. If you’re looking to purchase


new kit as a job shop, I wouldn’t worry too much about investing in the highest-power fibre lasers available. Suppliers are now saying: ‘We’ve got 10kW+ of power now, which can be used to cut 25mm stainless steel.’ However, there aren’t


“Whether you’re a newcomer or an established job shop looking to buy some new kit, a fibre laser is the way to go”


Table 1: Comparing the cutting speeds of 5kW fibre/CO2


Cutting speed – CO2 laser (m/min)


10.0 12.0 15.0 20.0


20.0 12.0 5.0 4.0 3.0 2.4 1.6 1.2 0.9 0.6 0.4


laser


cutting machines on varying thicknesses of stainless steel Thickness (mm)


1.0 2.0 3.0 4.0 5.0 6.0 8.0


48.0 24.0 11.0 6.5 5.0 3.7 2.0 1.0


0.75 0.45 0.22


many jobs at that thickness. I’d therefore recommend focusing on the 4-8kW range of power, which can tackle all the general thicknesses (anything below 20mm mild steel and 15mm stainless steel) that you’ll be required to process as a job shop – while not costing as much as the latest higher-power systems.


The majority of job shop


laser cutting involves metals below 6mm thick, and a lot of it – as mentioned above – is below 3mm thick, so you’ll want to focus on being fast and productive at these sections. The fact that you won’t be able to cut above 20mm thick steel is generally irrelevant, as those jobs are very infrequent.


Even if you could cut those thicknesses, the parts are often far too heavy and impractical to load and unload for the job to actually be worth it! In addition, because as a job shop you’ll find that most time is spent simply loading and unloading the jobs, even if you had a 10kW+ system you’d soon find that the higher cutting speeds it can offer for lower thickness jobs don’t have much of an effect on the total job time. Another point to consider is that the increasing availability of automated loading and unloading capability – which enables ‘lights out’ operation – is really only going to be beneficial for manufacturers looking to produce large


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Cutting speed – fibre laser (m/min)


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