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CONFERENCING IN CREWE: Matthew Dale shares three applications of laser technology presented at ILAS 2019.

In March I had the pleasure of attending ILAS, the Industrial Laser Applications Symposium hosted by the Association for Industrial Laser Users (AILU).

The two-day user-oriented conference--at the palatial Crewe Hall in Cheshire, UK--was packed with talks on welding, cutting, additive manufacturing, drilling, marking, process monitoring and much more. It provided me with a great opportunity to step away from my desk (and an inbox filled with the many product press releases and success stories of laser manufacturers), and really delve into the world of users and the exciting applications they address on a daily basis with laser technology.

Below are three applications that caught my eye.

Electrifying aerospace

Clive Grafton-Reed, Rolls Royce's global process owner for laser processes, opened the first speaker session by saying that laser processing is on the rise and facing new challenges in the aerospace industry.

Laser marking, for example, is now being increasingly used to add fine marks to aircraft parts to increase their traceability and to combat fraud. Lasers are also being used more and more to drill cooling holes in the turbine engines of aircraft--the number of which has increased from tens of thousands to hundreds of thousands of holes per engine over the years, according to Grafton-Reed (see feature, page 18).

New challenges in laser processing are arising, however, due to the advent of electrification in aerospace --which Grafton-Reed said needs to happen to meet the 2050 emission and noise targets set by the Advisory Council for Aviation Research and Innovation in Europe (ACARE). Engine C[O.sub.2] and NOx emissions must be reduced by 75 per cent and 90 per cent respectively by 2050, while aircraft noise must be cut by 65 per cent --considerably lower than currently achievable.

'This is a huge challenge,' Grafton-Reed said. 'Some of the engines in development will close a large part of this gap, but we have a long way to go.'

After its success developing an electrical propulsion system for ships and hybrid-electric systems for trams and trains, Rolls-Royce is now pursuing electrification in aerospace, and has announced its intention to break the electric airspeed record to demonstrate its commitment to electrification. This will be done by a fast, small, all-electric single-seater demonstrator aircraft being built by Rolls-Royce, scheduled to fly for the first time in 2020. This project is in partnership with battery manufacturers, with funding from the UK government.

In another collaboration with Airbus and Siemens, Rolls-Royce is producing a hybridelectric aircraft demonstrator, E-Fan X, which will be on the scale of today's single-aisle aircraft. The demonstrator will operate both on standard kerosene aircraft fuel and electrical power stored onboard. This will require the integration of a 2MW electric propulsion unit and a 2.5MW power generation system from Rolls-Royce, in addition to a 2MW battery from Airbus and a 2MW motor from Siemens --which will power the electric propulsion unit.

'This is where we're going and this is where the laser industry will be coming along with us,' said Grafton-Reed. 'Applications such as drilling, welding, cladding and marking--all of those have got to be better by being faster, producing tighter process results and being more efficient.'

While he assured attendees that current laser applications in aerospace are not going to disappear--turbines still need to be optimised further to offer greater efficiency, lower emissions and lower required maintenance--Grafton-Reed emphasised the growth of electrical systems in aerospace will require new laser processes. These will involve copper welding for battery production, dissimilar materials welding, and the processing of new alloys. Each of these new processes will require further research before they can be made reliable enough for production.

Grafton-Reed concluded by highlighting that closed-loop or 'near-closed' loop process control will be an absolute necessity for guaranteeing the quality of these processes, when producing electrical systems with ultra-high reliability. 'I sincerely believe that we can't just put a robust process in, we're going to have to monitor it and control it extremely closely. And we have to have a lot more data coming out of the processes in our factories so that we can confirm everything is absolutely on the button.'

Process control will be key for achieving 'green button' processing, which Grafton-Reed described as 'a machine operator only ever being faced with two choices throughout every step of an application --either yes or no, to either continue processing, or cease processing'.

Compact cutting for de-commissioning

Two years ago, at ILAS, Rolls-Royce's on-wing technology specialist James Kell impressed attendees by introducing a small, flexible, fibre-fed laser probe containing a number of focusing optics and a steerable mirror. The firm developed the device for deploying in aircraft engines, using a snake-like robot to perform blending repairs on turbine blades. The way that laser light could be delivered to such a tight space to carry out a complex application was, to me, nothing short of astounding.

At this years' symposium I was reminded of Kell's talk when Dr Simon Kirk, a research fellow at the United Kingdom Atomic Energy Authority (UKAEA), described to attendees how it--in collaboration with TWI and Cranfield University--has been developing compact laser cutting and welding heads for decommissioning components in its fusion reactors.

Whenever a component in a fusion reactor needs to be removed and replaced, the many cooling pipes surrounding it have to be cut and re-welded. These pipes have an inside diameter of 90mm--no larger than a pint glass, Kirk said--and walls that are 5mm thick. To this end, the UKAEA has been developing prototype in-bore robotic tools that can perform laser cutting and welding processes in these pipes.

The prototype laser tools include a novel miniaturised laser head design to fit in the pipe and apply the laser processes at a short standoff distance of around 25mm. The heads include a clamping function that stabilises and aligns them in the pipe, and a rotary function that enables the laser to be used to either cut or weld around the entire inside of the pipe. The clamping function of the welding tool also includes a large pneumatic actuator that clamps onto either side of the gap and pulls together so the weld can be performed. While the cutting tool was trialled with a similar feature, which would work the other way and pull the sides of the cut apart, Kirk noted trials revealed this function wasn't particularly needed.

The trials demonstrated that the cutting head could achieve full penetration cuts on 5mm-thick pipes made of two types of steel (P91 and 316L) in approximately 34 seconds. The laser binds the kerf material to the exit side of the cut, which significantly reduces the amount of secondary waste that later needs to be dealt with. For the initial demonstrator trials the quality of the cuts was not a primary concern, Kirk said, but explained later that further development of the cutting head and processing parameters could, in the future, make it possible to produce cuts that are re-weldable.

Trials of the welding head, on the other hand, demonstrated that, while full penetration welds could not be achieved on steel pipes of the required 5mm thickness, pipes that were 3mm thick could in fact be welded successfully. The power required to perform welding at 5mm thicknesses could not be sent through the head, Kirk commented.

The power that could be sent through the welding (and cutting) head successfully was up to 2.3kW. Kirk added that while a lot of individual components were rated to about 5kW, the cooling systems of the heads--argon gas flowed through the central optical cavities--can only hold on for so long at this power. An additional issue, Kirk said, was the laser spot size used for welding and cutting was limited to around 0.8mm. This was due to the short standoff distance of around 25mm between the head and the pipe, which means only very short focal length optics can be used.

One tool, three applications

On day two of the symposium, an upcoming technology that caught my attention was the multifunctional processing head under development in the European Horizon 2020 project ModuLase, coordinated by TWI, which began in late 2016 and is due to continue for another nine months.

The new processing head, according to Dr Jon Blackburn, manager of TWI's laser and sheet processes group and vice president of AILU, will be capable of performing three processes: welding, cutting and cladding. This will be achieved through three interchangeable end effectors--one for each process. Currently these end effectors have to be changed manually. However, Blackburn assured that this will eventually be done via an automated robotic tool changer.

What drew my attention to this multi-functional system was the interest it has sparked among manufacturers. The technology was originally intended for job shops and tier-2/3 manufacturers, that not only undertake a lot of highvariety projects at relatively low volume, but who also might not have the budget to procure a range of different processing heads, or the expertise required to support a wide variety of applications. Blackburn said the project has since attracted a lot of attention from larger, tier-1 manufacturers as well, which have expressed interest in using the new processing head to develop multi-functional production cells that would allow them to compress the footprint of their factories.

The processing head features a new, automatically driven re-configurable optics technology, called Beam Forming Unit (BFU), which has been developed to deliver a range of energy distributions suitable for welding, cutting and cladding. In this way, downtime due to changing from one process to another will be considerably reduced.

Process monitoring capabilities are also offered by the new system, both through a beam splitter and multiple camera-based CMOS sensors that are able to measure back-reflected radiation in wavelengths ranging from the visible to the infrared. This gives the operator the ability to determine whether each process is being performed to the required quality during processing.

The system is able to handle powers up to 10kW and is targeted for use with continuous wave (CW) fibre lasers. All the powder and gas required for the three types of process it offers will be delivered through a gas delivery unit (GDU).

The user interface of the processing head is linked to a knowledge database comprising the cumulative experience of TWI and its partners, which can be searched by operators to obtain the optimal parameters for a process. The optics of the processing head can then be reconfigured automatically via on-board intelligent algorithms, using the selected parameters, to deliver the required beam caustic for the process.

With the hardware developed TWI is now in the process of performing lab-scale validation trials of the system, referring to the industrial case studies selected in the project, covering the automotive and power industry sectors. The whole system will then be delivered to CRF, the research arm of Fiat and a project partner of ModuLase, in Q2 this year so they can use it in one of their production cells, for validation in a manufacturing environment. Prior to this, TWI has tested the system on the same materials and sheet thicknesses that Fiat deals with--dual phase, 600 MPa, zinc-coated steel at a sheet thickness anywhere between 0.8 to 1.6mm--and has been able to achieve results that match the quality and geometry specifications of Fiat's welding applications, and at the same level of productivity.

'Then, with the same process head but with a slight adjustment a minute or two later, we were able to cut out the bits of the material that Fiat want to cut, using the same laser and the cutting end effector,' Blackburn concluded.

The ModuLase project has received funding from the European Union's Horizon 2020 research and innovation programme and is an initiative of the Photonics and Factories of the Future Public Private Partnerships.
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Title Annotation:SHOW REPORT: ILAS 2019
Author:Dale, Matthew
Publication:Laser Systems Europe
Date:Jun 22, 2019
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