Automate to accumulate

Fibre and fibre-delivered lasers are now the dominant laser source for sheet metal cutting, taking market share from the older, more traditional CO2 laser. The speed of the shift to fibre technology has been remarkable considering the investment needed to buy and maintain laser equipment, but it’s not just about the source when it comes to sheet metal working.

‘In the past, laser system developments for sheet metal processing tended to revolve around increasing power,’ explained Dr Heinz-Juergen Prokop, head of machine tool development at laser system maker Trumpf. 

After that, Trumpf started to offer more processing assist tools, such as beam focus position control or cutting nozzle inspection.

‘Now, our machines are running well,’ Prokop continued, ‘but our customers find that production systems are getting more complex, lot sizes are smaller, their customers want to be served as fast as possible, and they find it more difficult to govern the volume of orders they receive. Therefore, we had to find solutions for that.

‘More of our customers say it’s not necessary to cut faster; instead they say help us, for example, to get the parts out of the machine faster.’

At the sheet metal processing trade fair, Euroblech, which takes place in Hanover, Germany from 25 to 29 October, Trumpf will be launching new machine concepts that fit these customer needs, in order to unload parts quickly and to network machines so that they are embedded in the logistics of the factory.

One problem with sheet metal processing is to get the parts out of the skeleton holding the sheets. This is especially true for thicker material, because if the parts are slightly tilted, they get stuck in the skeleton and cannot be removed with just a suction port. Trumpf will present solutions for this at Euroblech.

Automation solutions are also the way successful machine tool suppliers like Trumpf, Bystronic or Amada differentiate themselves from low-cost companies entering the market, noted Frank Gäbler, director of marketing at laser supplier Coherent. ‘Sheet metal processing is not necessarily all about the laser; the machine performance is critical,’ he said.

Giulio Amore, 2D laser product manager at Prima Power, which makes laser and sheet metal machinery, agreed: ‘Laser technology has now reached a very high consistency in terms of reliability and stability; automation and part handling are strongly required.’ He went on to say that, when calculating the cost of laser processing, the cost per hour of the operator is where the main savings can be made, especially in factories in Europe. The answer lies in automation and laser sorting systems, he said.

Fibre providers

Fibre lasers have largely taken over from CO2 machines in sheet metal cutting – their success, according to Dr Wolfram Rath, product manager at Rofin-Sinar Laser, being because of their high wall-plug efficiency, the nearly maintenance-free technology, as well as the high process efficiency at an affordable cost of ownership. Fibre lasers are also much faster than CO2 systems at cutting thinner metals of around 2-4mm thickness. Rofin supplies laser processing systems, and has recently been bought by Coherent.

At the Lasys trade fair for laser material processing, Dr Christian Schmitz, managing director of development and production at Trumpf, described CO2 lasers as retaining ‘niche’ markets, which shows just how far fibre laser technology has come, considering CO2 used to be called the ‘workhorse’ of the industry.

Prokop at Trumpf, speaking to Laser Systems Europe, commented that the company still thinks there is a place for CO2 lasers in sheet metal processing, a sentiment echoed by other system suppliers. Matt Wood, a senior product manager at Amada Europe, commented in an article about job shops in the Summer 2016 issue of Laser Systems Europe that ‘subcontractors that need to process a wide range of materials and thicknesses are still not convinced that fibre lasers are good for cutting thicker material’. He added: ‘These companies have gone down the route of the latest CO2 technology, which I can’t say I’m surprised about in a way because, in my experience, fibre lasers still aren’t comparable to CO2 systems for cutting thicker aluminium and stainless steel. For high quality cutting in thick materials, then the CO2 laser is still the way to go.’ Amada continues to sell CO2 lasers to subcontractors replacing older machines, according to Wood.

‘The strength of CO2 lasers is nitrogen cutting,’ added Prokop. To date, fibre lasers do not offer equivalent cutting quality when using nitrogen compared to CO2 systems. This is normally not required by the majority of laser users, according to Prokop, but some customers need to have cut surfaces that are almost like a mirror, he said.

In addition, many operators are used to CO2 lasers. ‘If there is a problem with the [CO2] machine then the operator knows that they have to change the focus position, for example, to fix it. With solid-state lasers, the results are sometimes different, which the operator has to get used to. We have a lot of customers that say our operators are familiar with CO2 systems and therefore we’re going to buy CO2 lasers again,’ stated Prokop.

Fibre lasers, however, are getting better at cutting thicker material and still producing a high quality edge, something they have struggled with in the past, according to Gäbler at Coherent. That’s done by changing the mode of the laser using a beam converter in between the cutting head and the laser, he said.

CO2 lasers have reached their optimum power, according to Prokop. Trumpf introduced an 8kW CO2 system, but for niche applications. ‘Most customers only require 6kW; this is the optimum as the market shows,’ he said.

By comparison, cutting speed is still increasing with laser power when using solid-state systems, especially for cutting thicker material above 3-4mm. Trumpf has an 8kW solid-state system in the cutting market, with 10kW and 12kW under development.

A consequence of higher power is greater automation, as Gäbler noted: ‘If laser machines become more powerful, then the machine dynamics and the mechanical setup also have to be advanced – you need to be able to translate the higher power into greater throughput and better quality. The higher power has to yield a tangible benefit for the customer.’

Gäbler also observed a trend to more automation in welding. ‘Manufacturers are trying to get complete solutions from one company, not only the laser but the welding head, the diagnostics and the process control,’ he said. ‘There are more laser companies selling optics as a complete subsystem, and I also see optics suppliers now selling lasers for welding.’

The direct diode approach

One of the benefits of fibre lasers over CO2 systems is their superior wall-plug efficiency. Direct diode lasers are even more energy efficient, and companies like Laserline and Teradiode have started offering high-brightness systems for metal processing. So will direct diode lasers usurp fibre lasers in the future for sheet metal working?

‘Direct diode lasers are competitive with fibre lasers for welding and surface treatment applications like cladding or heat treatment, where you don’t need a high brilliance beam,’ explained Gäbler. In these applications a beam parameter product (BPP) of 8mm x mrad or even 20mm x mrad is sufficient.

However, high power direct diode laser cutting needs a beam parameter product of 4mm x mrad or better. ‘There is limited availability of such lasers as yet,’ Gäbler added. ‘Plus, decisions about which laser technology to use also include other considerations, such as laser reliability, cost of ownership and the vendor’s service model. We know that companies are working on products that excel in all these areas, but it’s still early days.’

‘We think the diode laser has a future because it’s the most energy efficient laser, even more so than fibre lasers,’ commented Prokop at Trumpf. ‘It’s also easier to manufacture, but because at the moment volumes are low, the diodes are expensive. We think that the technology has a future though.’

Trumpf is developing and selling direct diode lasers, mostly for soldering to date, although it is developing cutting lasers using direct diode. ‘It’s more difficult to get the brightness and the beam quality with this technology, because there’s a limit to combining beams through a 100µm fibre at high power,’ explained Prokop. ‘New dense coupling technology shows that it is possible to combine slightly different wavelengths on the same spot to give high brightness. Trumpf is also working on this.’

Rofin will present a 4kW direct diode laser for welding at Euroblech. ‘Today, the direct diode laser is already used for sheet metal welding tasks,’ stated Rath. However, he added that fibre lasers have big advantages over diode alternatives when it comes to cutting, namely higher beam qualities and higher output powers, which can be achieved at lower costs and comparable wall plug efficiencies. Rath also noted that there is more choice when it comes to fibre lasers – Rofin’s fibre lasers are available with output powers from 500W to 8kW.

Factories of the future

‘The introduction of Industry 4.0 will continue to transform sheet metal processing,’ commented Amore at Prima Power, thanks to sharing, collecting and managing data to adjust process parameters and improve production. Industry 4.0, or the fourth industrial revolution, looks to use automated solutions and data exchange to make factories more productive.

Alongside its fibre laser source, Prima Power is developing process sensors and software to manage the performance of the laser system and production reporting.

Trumpf has established a software subsidiary called Axoom, a platform that aims to help manufacturing firms organise their shop floors. ‘In the future, we think it will be possible to have a nearly automatic flow of processing orders, from an initial customer enquiry all the way to invoicing,’ commented Prokop.

Bystronic is also developing smarter laser tools; it’s most recent fibre laser, ByStar Fiber, is based on a control system that includes new sensors to measure and analyse the cutting process.

The big system suppliers like Trumpf face competition from smaller firms offering low-cost lasers. Prokop said that cheaper machines don’t have the same stability or tools that assist the operator. In addition, the more established laser system suppliers offer better service, spare parts, training, and knowledgeable sales staff to consult with on applications.

‘We are lucky that the market is still growing and that Trumpf hasn’t lost volume yet, but we have to find solutions that will be the next step, such as fully automated systems,’ Prokop commented. ‘Industry 4.0 or smart factories are part of that trend.’ He added that it’s not just the western countries, but also China, and the Asian markets in general, that are interested in solutions offering easy order processing, and that give key production data at different processing steps.

‘Trumpf’s vision for the future is to have autonomous laser systems that can control the cutting process, ending finally in the autonomous factory,’ Prokop concluded. ‘This will perhaps take more than 10 years, but step by step we will get there.’ 

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Sheet metal working