Energy

Interview with Dr. Wojciech Suder

by Fleming. Team

We have asked our prominent trainer - Dr. Wojciech Suder (Research Fellow in the Welding Engineering and Laser Processing Centre at Cranfield University), about the future of laser welding, its advantages / disadvantages, interesting cases and much more.

1. What do you expect from laser welding in the future? Is there going to be a wider use/application than today?

"If you think how great flexibility and control of the applied energy, combined with directionality and precision is possible with lasers, I have no doubt that their use in industry will be rising in the future. I believe that due to significant improvement in reliability, efficiency and decrease of cost per kW of power output, the lasers will dominate many welding applications. Key aspect in this is the knowledge of benefits and limitations of the process and understanding of the basic principles, as well as good working practice and education of future engineers. Like every new technology it requires new mind set and willingness across industry to achieve major step change in welding technology. This will be necessary to facilitate the demand for cleaner, more efficient, more flexible and greener technology, imposed by legislation and competition. I envisage increase in use of lasers across all spectrum of material joining, but definitely the biggest in all mass produced goods and high tech applications."

2. Where do you see the advantages/ disadvantages of laser (keyhole) welding?

"Laser welding has many advantages, but the most important is its precision. This applies to two aspects. With lasers it is possible to accurately specify the amount of energy that is required to weld a particular part and this energy can be precisely applied. We have a choice of applying the same energy on a large or a small spot size with many variants of pulse shaping, beam profiles etc. Secondly, the directionality and non-contact nature of laser processing ensure that the material is heated only at the point where is exposed to the laser. The lasers are also easy to interface and implement into fully automated production machines.""Speaking of disadvantages the main one is the vast amount of variables that can be changed and have an effect on the response of the material, but this is linked with lack of knowledge of the process. It is very tempting to develop processing parameters based on engineering approach by tailoring welding power and travel speed to penetrate the material. But in such a case we rely on luck rather than on full comprehension of the process, which can undermine robustness of our process. Robust laser processing requires basic knowledge of the process principles and rules that need to be followed. Like every advanced technology, also laser welding requires better accuracy of the set-up, and stricter control of welding parameters, as compared to traditional welding techniques. Often most problems originate when we try to apply lasers to the existing set-up without taking into consideration additional accuracy requirement and with limited understanding of it. We just have to remember that laser welding is not the best option for everything."

3. Can you tell us some interesting case you worked on? What part of your research are you most proud of?

"The most interesting project that I worked recently was on development of technology for joining of carbon fibre composite with metal for light weight structure applications. We came up with an idea of using special sandwich structure with multiple layers consisting of metal and composite. Each of these layers was welded together by means of multiple cylindrical stiffeners, which resulted in relatively complex lightweight structure with optimum combination of stiffness, toughness and weight. However this approached required hundreds of welds to be performed in a short period of time under the strict requirement of energy control to make sure that each stiffener was welded to the plate but without extensive heating of composite. Also during the assembly stage a series of precisely drilled holes had to be made in each metallic component of the sandwich structure to enable perfect fit of the structure before welding. After many iterations using various drilling techniques and welding processes the most successful outcome was achieved with laser processing. In this case the same laser was used for drilling of holes and welding of the cylindrical stiffeners. This demonstrates great versatility of lasers, where two completely different processes, such as welding and drilling, could be achieved on one machine just by appropriate control of applied energy. Also with laser the production rate was much faster than with conventional processes."

4. When somebody says “welding” people usually think of it as a very dangerous kind of job. Have you ever suffered an injury during your work?

"No I have never had any injury during work. Although welding is perceived as dangerous and dirty environment, but when you comply with safety regulation and follow a few golden rules it is completely safe environment. The biggest danger of laser welding results from the fact that we cannot see the danger because most of lasers emit in invisible range of radiation spectrum. By the way in arc welding also the invisible UV radiation is the most harmful. There is a wide range of different screening methods and interlock systems, which are commonly used to minimise the danger to a safe level. In most cases all ancillary equipment, such as robots and manipulators is usually more dangerous than welding itself."

5. Can you give us a little teaser on what our delegates can expect from the training? You have been working at the Cranfield centre for several years, and our course gives them the opportunity to visit the Welding Engineering and Laser Processing Centre. What can they expect?

"As a research and academic institution we have been exposed to a broad spectrum of technology and therefore can build our own opinion on the suitability of a given process. Also since we do not have any profit from selling equipment we can give you an honest and unbiased opinion regarding the best solution to a given welding problem/application, unlike equipment manufacturers, which will try to convince you that their system is the best for the job. The delegates can expect comprehensive but yet compact training on all the most important aspects of laser processing, knowledge of which is necessary to ensure robust processing. In our lab you can see many state-of-the-art welding processes in action, from high power laser welding, laser cutting to micro processing and marking, as well as other non-laser welding processes, such as arc welding, additive manufacturing and other innovations. Our enthusiastic and knowledgeable research staff will be happy to answer any intriguing question on any aspect of welding technology."

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