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Cyan Tec to improve nuclear decommissioning efficiency for UK Nuclear Research Centre

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Cyan Tec Systems has been selected to design and build an exciting custom laser welding system for the Nuclear Advanced Manufacturing Research Centre (Nuclear AMRC), one of seven High-Value Manufacturing (HVM) Catapult centres funded by Innovate UK. The Nuclear AMRC in Rotherham will be taking delivery of the turnkey system before the end of 2017. Cyan Tec, based in the UK’s high-tech heartlands in Loughborough, has extensive experience in integrating high power fibre-delivered lasers in large systems for automated laser welding and cutting.

Bjoern Kraemer, a Laser Engineer at the Nuclear AMRC, outlined the reasons Cyan Tec were chosen following an open and competitive tendering process:

“Cyan Tec provided the best response to the Nuclear AMRC’s tender process. They not only addressed all of our requirements in an appropriate manner, they also showed great knowledge and professionalism by presenting their innovative solutions at the right level of detail and providing a selection of options. Cyan Tec provided a competitive and unique turnkey solution with a comprehensive service package which will satisfy all our demands for a high-quality manufacturing solution.”

The Nuclear AMRC helps UK manufacturers win work in the civil nuclear sector and assists them in the development of new technical capabilities and processes. Situated on the Advanced Manufacturing Park in South Yorkshire, the Nuclear AMRC research facility offers an array of state-of-the-art equipment for machining and fabrication, supported by in-house engineers and researchers, all of which are made available to manufacturers to use in collaborative R&D projects.

Cyan Tec’s advanced laser cell will further enhance the welding capabilities of the Nuclear AMRC to support manufacturing process development for key nuclear components. One example is the duplex steel boxes used to store hazardous waste from Sellafield and other decommissioning sites – laser welding can significantly reduce manufacturing times and costs while maintaining a high quality of weld seams. The innovative Cyan Tec welding cell will be used to develop and optimise these welding processes, as part of a programme to save hundreds of millions of pounds over the life of the decommissioning programme.

The system is designed for deep penetration welding for R&D of laser and hybrid laser and arc welding. With the highest power Disk laser in the UK, delivered by fibre optic cable, the system will have a wall-plug efficiency higher than 30% and is fully protected against back reflection which is vital in high power welding of reflective materials.

Integrated with a 6-axis gantry system, the overall cell has the capability of delivering a simultaneous MIG weld for deep penetration hybrid welding with hot wire or cold wire feed.  The system includes a large tilt and turn manipulator which can carry components up to 15 tonnes and overall the advanced CNC controller is able to interpolate all 8 axes simultaneously to weld complex seams with perfect results. Such a system is a challenge for an integrator of automation and CNC systems, but falls easily within the capabilities of Cyan Tec’s team of experienced laser integration engineers.

With such a high average laser power delivered by fibre optics, and a system capable of steering the beam in all directions, laser safety is extremely important.  Cyan Tec have developed their own safety solution, comprising an active guarding laser safety enclosure of dimensions 10 m x 7 m and 6 m high. The safety system has an actively monitored cavity wall with instant shut-down in the event of any break-through of the outer layer.

Modern motion systems are faster, have higher accuracy and vastly-improved repeatability compared to previous generations. Cyan Tec Systems has experience of integrating robots and CNC systems with lasers from all the major suppliers and can offer expert advice on the most appropriate solution for laser processing. Standard and bespoke systems are offered with a full service from design through manufacture; a large installed base worldwide is supported by a dedicated team of engineers.

The innovative Cyan Tec design configuration is shown in the image below.

Robot Laser Welding Cell is Flexible & Fast

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To address the needs of the white goods and automotive industries in particular, expert system builder Cyan Tec Systems of Loughborough has developed a standard multi-axis robotic laser welding cell incorporating a 6-axis robot combined with a 2-axis tilt-and-turn manipulator to give the ultimate flexibility with 8 programmable axes. Such a system can work on large components or assemblies and present them in such a way to reduce the complexity of the robot moves and compress the overall cycle time.

More and more welding tasks are becoming automated as the lack of availability of skilled and experienced manual welders, and the requirements to achieve stringent and repeatable quality and higher throughput, drive production away from conventional joining processes towards laser welding.  In addition to this, the current trend in reshoring production from abroad promotes a high degree of automation which minimises the impact of international differences in labour rates, and reduces the cost and uncertainty associated with long distance logistics via sea or air freight.

The Hyperion MAR30WF is a standard system built by Cyan Tec using a 6-axis robot carrying a compact laser welding head from a multi-kW fibre laser source. The tilt and turn manipulator has an integral indexing system allowing parts to be safely unloaded and re-loaded during the welding cycle by an operator outside the Class 1 safety enclosure. Welding by laser is a non-contact process, where the laser beam is typically some distance from the final focusing optic. For best results a pipe delivers Argon assist gas which prevents oxidisation, leaving a bright and oxide-free weld which is capable of coating or painting after welding without any need for post-weld cleaning.

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Image: Standard Multi-axis robot laser welding cell

A highly efficient laser welding cell can be modified to process new products by simply re-programming the software and re-tooling for new configurations. Using a dedicated cell with a standard design gives the benefit of reduced cost and lead time for the capital equipment, as custom machinery is limited to the final tooling and the welding path programme.

Laser welding has the benefits of low heat input and excellent repeatability.  The accuracy and consistency reduces the amount of material required in flanges and enables novel joint arrangements since only single-sided access is required (unlike resistance spot welding).

Modern robots are faster, with higher accuracy and repeatability than previous generations. Cyan Tec has experience of integrating robots and lasers from all the major suppliers and can offer expert advice on the most appropriate solution for laser processing, paint spraying, assembly, test as well as many other applications. Standard and bespoke systems are offered with a full service from design through manufacture, a large installed base worldwide is supported by a dedicated team of engineers.

How is laser welding better than TIG?

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Arc welding as a production process took a long time to become established, but has nevertheless been around since the 1940s.  Although the laser was only invented in 1960, it quickly became established as a production process and by the 1980s was starting to be used in high volume manufacturing.  Recent advances which have improved the beam quality and efficiency of lasers, make the laser an even more advantageous solution to high volume or automated industrial joining.

Weld quality and consistency

Laser welding enables the quality and consistency of welding to be readily controlled and consistently maintained.  Since the laser head makes no contact with the workpiece and there is no electrode which can become worn, eroded or damaged there is no need for a tool change where the electrode needs to be reground or sharpened, as is the case with TIG.  The lack of electrode dressing in laser welding results in higher uptime and longer time between maintenance interventions.  Also, there is no risk of contamination of the weld material with Tungsten from the TIG electrode tip when striking the arc.

Lower heat input

With laser welding the heat input to the metal being welded is lower which means there is a smaller heat affected zone (HAZ) and the distortion of the assembly is vastly reduced making complex and accurate assembly more achievable, especially in an automated setting.

laser weld microTIG weld

TIG welding (left) typically exhibits higher heat input into the surrounding material – Laser welding (right) is capable of finer welds, with a much smaller heat-affected zone

In addition, the lower heat input means that a weld can be placed close to sensitive electronics or other heat-sensitive materials without risk of damage or failure.  An example of this is in cardiac pacemakers and defibrillators where the external weld seam is directly above a heat-sensitive battery and micro-electronics which cannot withstand a temperature over 80 degrees C.

Throughput – higher welding speed

Weld speeds are generally higher with laser welding, especially with modern high power continuous wave (CW) fibre lasers.  A high welding speed sometimes means that the motion system, for example the CNC system or robot contouring speed, is the limiting factor on cycle time rather than the process.

Cost per metre of weld

In processes where throughput is high it is common to find that the laser solution is more efficient and results in a lower cost per metre of weld.   Interestingly, there are processes which combine laser and arc welding to achieve deeper penetration and higher welding speeds.  These hybrid processes typically use a combination of laser welding to heat the metal efficiently to melting point and arc welding to provide deposition of droplets into the weld pool and enhanced penetration and weld strength over either process as a stand-alone procedure.

No finishing of the weld

With inert gas shielding, a laser weld in stainless steel or aluminium normally requires no post-processing (grinding or dressing) after welding, the weld finish is bright and oxide free and can be typically coated or painted without further cleaning steps.

Access difficult areas

Since the laser beam is a “line of sight” process, the laser can pass through gaps in a structure to weld areas from the rear, where it would not be possible to introduce a TIG electrode.  Using a camera to view through the laser optics, it is easy to align the beam to a precise feature and perform welds in difficult-to-reach parts of the structure.

What about gaps?

One disadvantage of laser welding is that it tends to rely on good contact and minimum gap between parts to be joined.  With either a laser process or a TIG weld, there is a need to ensure that gaps are minimised or avoided to ensure good results.  With the addition of wire feed, which adds a certain complexity to the process, it is possible to fill gaps or build up areas for additional strength.

Conclusions

For ease of automation, consistent quality and lack of post-processing there are clear advantages to using laser welding.  Where welding is to be applied manually, TIG welding has greater flexibility and lower capital cost for the equipment.