Industry News
Cost-effective cutting using power fiber lasers

Laser cutting is a process that is outsourced to specialist job shops. This article presents the affordability of cutting with medium power fiber lasers.

Across many industries today, laser cutting is a process that is outsourced to specialist job shops which are set up for the sole purpose of high volume, high quality metal cutting. These companies can accept on any given day a wide variety of metal types and thickness and so the machines they use require a great deal of flexibility and performance. This application note looks at the affordability of cutting with the medium power fiber lasers; it focuses on a specific case study where SPI works with a jobshop to create a machine at 50% of the cost of the more traditional laser cutting machines.

The high end laser cutting machines deployed in job shops can cost in the region of US$500K to buy and so need to be operated on a 2 or sometimes 3 shift basis to recover the return on this high capital investment.

To support the ROI calculation, the machine builders are encouraged to use ever more powerful lasers and claim faster and thicker cutting data for their machine. This eventually becomes a cycle of events which pushes up machine performance but also price and so reduces affordability. However there is another way to look at the requirements of industry to cut metal.

Affordable laser cutting

What if the end user (consumer electronics company, white goods manufacturers, HVAC supply etc) wished to keep the metal cutting in-house and not send it out to a specialist job shop? What would that mean for the performance and price requirements for the cutting machine?

A specific company tends to know how thick its metal parts will be, and so does not need to allow for a parts range of 1-25mm. A very high percentage of parts are made from metals less than 2-3mm thick. Companies only working on a single shift would only want a machine to run a single shift so lights out operation considerations do not apply. Volumes may not be so high and therefore speed not such a consideration.

 In fact a specific machine, going into a specific factory, may look very different from a general machine going into a job shop. But different in what way? One key consideration is not to lose the cut quality, in fact if anything to improve it, but to create a machine concept that is fully affordable to end user companies both due to capital cost and also operational cost savings.

Since the number of end user companies probably is a factor of 100 greater than the number of specialist cutting job shops then perhaps there is an opportunity for cutting machine builders similar to that from low cost airlines many years ago.

Machines built to a budget and specification purpose fitted to the end user market could move laser cutting into the factory and away from the specialist shop.

Key considerations

If we focus on 2-3mm thick metals and cease to make cutting speed the key criteria then a high quality but low cost beam source such as the SP 400C fiber laser from SPI can be applied. The all-in fiber delivery cable enables this to be straightforwardly coupled to a light weight and compact process head such as the “Fiber Mini” available from Laser Mechanisms Inc. This “flying optic” configuration leads to a number of benefits that impact the design and cost base of the cutting machine.

Cutting speeds at 1mm thickness in the region of 10m/minute will mean far less impact from acceleration and deceleration of the process head, which in turn enables a lighter frame with lower cost motion systems can be used. The lightweight process head at 2.5kg has little demand on the gantry weight bearing capability.

 Repeatability

A key feature of the fiber laser over other laser sources is the high energy density when the beam is focused to spot sizes in the range 30-100μm. This enables not only compressed air cutting of steels but also cutting of reflective materials such as brass, aluminium, and copper.

The same feature also enables the laser to cut highly intricate shapes or precision parts. This however places a requirement on the machine builder design the motion system to a repetitive position accuracy of +/-0.025mm. Components such as motors, encoders, drive systems, and gearbox must be specified accordingly.

Additionally the requirements on the CNC control to achieve the best performance mean that many component used are more typical of the world of laser beam source machines rather than that of plasma beam source machines.

Eye safety

Laser cutting machines based on 1μm sources need to take into account eye safety considerations at this wavelength. The laser radiation must be confined within a Class 1 laser safety enclosure resulting in machine designs such as the example shown in Figure 2.

Return on investment

The end user, as with the job shop, is always considering the return on investment possible from a capital purchase. The machine may cost 50% of the higher performance machines but will it pay for itself whilst cutting at half the speed.

Techinwest have shown their many customers that by using a beam source offering 90% better energy efficiency than C02 sources, and opening up the possibility of compressed air cutting the investment decision becomes easy. Often the machine may be compared to high definition plasma based machines but here other considerations come into play. The fiber laser can common line cut material and has a fine (0.1mm) cut kerf.

The combination of these offers the capability for highly dense nesting and so a material saving on each sheet of metal. Users can see this translate into many thousands of $ saving each year in metal.

Each company has different requirements for metal cutting and so SPI has created a cost calculator sheet looking at many of these aspects. In discussion with a particular customer we can usually determine the cost per meter cut from their current methods and the cost per meter cut from a fiber laser based low cost cutting machine. 

Source : Industry Sourcing

June 2017

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