1. Being the Head of Design & Manufacturing Technology Division at Raja Ramanna Centre for Advanced Technology; how has been your journey so far?
In 2022, I was elevated to the position of Head of Design & Manufacturing technology Division (DMTD). The mandate of the DMTD is to develop products and joining technologies and helping others in realising their designs by precision manufacturing, surface treatments and state of art joining.
At the outset, I prioritised rigorous implementation of Manufacturing ERP software to synergise user’s requirement with the division’s efforts. This implementation not only helped in optimisation of resource allocation but also reduced the non-conformities due to addition of a reception module. The reception module sets a dialogue between the user and the division so that a synergy is established between requirements and deliveries before starting physical progress. The software also provided visualisation of real time data for facilitating decision making to DMTD as well as to the user’s division. We issued a manufacturing rate contract to outsource some of the works to local industries so the project timelines are not compromised due to lack of internal resources. We also took up a maintenance campaign to bring all machines into operation with their full specification. We made a policy decision of including the machine operator and shop supervisor in the maintenance crew of a machine tool to improve their engagement.
Another major challenge was to lead a team of about one hundred technocrats with a goal of swift delivery of extremely challenging precision components and novel technologies in line with projects’ schedules. The culture of a technology intensive place is extremely important. I encouraged people to develop the habits of reading a lot of published works, publishing their own work and expressing their opinion freely without any bureaucratic hurdles or hierarchical biases. We could set a system which values independence over obedience. Empirical creativity is encouraged so that implementable, economical and scientifically valid ideas only pass through the brain storming sessions. Everyone is encouraged to come out with ideas and participate in brain storming sessions irrespective of their level. As a result, at times, we have got astonishingly brilliant out-of-the-box ideas coming from lowest rung of technocrats like welders, turners, machinists, fitters and metrologists.
We normally focus on the ways in which the idea / concept / design can fail and then try to plug all possible modes of failure through subset of new ideas. Concepts and designs are verified and adapted through numerical simulations using computational tools like finite element analysis, explicit dynamics, multibody kinematics, electromagnetics and computational fluid dynamics before progressing to manufacturing and experiments. The route looks long and arduous but in reality, it proves to be the fastest and most economical path of development of new technologies and products.
DMTD tries to pre-empt the requirements of joining technologies to start its own research project so that main projects do not suffer from uncertainties. Recently, we have developed aluminium alloy – stainless steel joints of 8” diameter for prospective application in Isotope Production Reactor. At present, we are trying to develop vacuum induction brazing technology to join two 2 meter segments for manufacturing of 4 meter long linear accelerator.
The newly developed products include ceramic insulated vacuum brazed non-magnetic electrical feedthroughs, PTFE insulated electrical feedthrough, SMA feedthrough, UHV compatible optical fibre feedthrough and binary gas mixing system. The technologies include Al-SS diffusion bonding, Al-SS vacuum brazing, Ti-SS vacuum brazing, Ti-SS diffusion bonding and nitrogen added TIG welding of SS316L. Activated TIG welding was implemented on the shop floor in manual as well as in automatic modes by addressing weld quality issues like concavity, higher ferrite content, and residual slag formation. The division has developed chemical additive manufacturing, popularly known as electroforming through which extremely challenging components have been manufactured with astounding success rates. Four technologies are in collaborative incubation for the benefit of Indian industry. Recently we have successfully manufactured a very complex design of new generation 1.8 meter long linear accelerator in a record time to meet project’s schedule.
I am happy to share that we could made three fold improvements in the precision manufacturing segment and an order higher output in technology and product development segment within 18 months.
2. Could you brief us on some of the major developments made by you during your career?
Dr APJ Abdul Kalam was one of the best technologists the country has ever produced but the most important contributions made by him to Indian science and technology are his ethical leadership and ability to form result-oriented teams. In technology intensive projects, individuals cannot make a significant difference unless they have the ability to work in large teams.
Since you have asked; I will talk about the projects in which I made significant contributions but I owe the success of these endeavours to the wonderful people in my team. In the long journey of 32 years, it is very difficult to shortlist a few amongst many but I will put an honest effort to do so. Radiofrequency cavities of Booster Synchrotron and Indus-1 were the first products in which I contributed by performing coupled physics numerical simulations and engineering design. These cavities are made of type 316L stainless steel with internal surfaces electroplated with copper. I made a breakthrough in post manufacturing tuning of these resonant structures by designing a simple tuning system which is functional even today. The present day Injector Mictrotron, the first particle accelerator to generate an electron beam in the Indus accelerator complex, was conceptualised and designed under my technical leadership. I made some pragmatic changes in the manufacturing, heat treatment and storage specifications of its cathode which eliminated instability problems, reduced performance uncertainties and improved the operational life as well. I also led the TIG welding technology development using a high manganese austenitic filler metal of ISO 14343 for producing fully austenitic weld metal during manufacture of its vacuum vessel made of type 316LN stainless steel. It is significant to note that the whole of the 27 km Large Hadron Collider (LHC) of CERN, Geneva is standing on RRCAT’s six thousand eight hundred ultraprecision alignment jacks. I was responsible for structural design as well as development of casting, forging, electroplating and quality assurance plan for manufacturing of these jacks at Indian industries. The jacks are capable of positioning a 15-meter-long magnet, weighing 32 tonnes, with an accuracy of less than 50 micrometres i.e. less than the breadth of human hair. I was a core member of the team that developed first elliptic superconducting radiofrequency cavity made of niobium. This technology is crucial for the development of accelerator-driven sub-critical nuclear power reactors fuelled by thorium. On the technology front, my team has developed bi-material joints of 25 material combinations for various applications at the Centre. We have also developed titanium-tantalum TIG welding process. We have developed full penetration TIG welding between porous pipe and solid pipe made of austenitic stainless steel and titanium for a filter manufacturing industry under our incubation. We have developed nitrogen added TIG welding of austenitic stainless steel by making consistent effort of about four years.
2. RRCAT being an R&D organisation under Department of Atomic Energy, Government of India, could you brief us on few major R&D projects undertaken by the Centre.
One of the Centre’s most significant achievements is the indigenous development of particle accelerators at a significantly lower cost compared to similar international facilities. Despite this cost advantage, the performance of these technologically complex machines remains on par with international facilities in terms of uptime, research papers published, and beam characteristics.
The Centre has successfully designed and built two electron accelerator-based synchrotron radiation sources: Indus-1 (450 MeV, 125 mA) and Indus-2 (2.5 GeV, 200 mA). These national facilities serve researchers and material scientists from across the country. The Indian pharmaceutical industry routinely conducts experiments at Indus beamlines to validate their drug development processes and obtain crucial data for licensing purposes. The synchrotron beamlines of Indus facilities have also played a vital role in calibrating software and detectors for ISRO’s Chandrayaan-I and Chandrayaan-II missions, as well as characterizing X-ray optics for its Astrosat mission. Additionally, the nuclear industry has benefited from Indus-2 beamlines through stress analysis of critical welded components used in reactors.
The centre has mastered the technology of building indigenous 10 MeV linear electron accelerator for medical sterilization and various other applications like agro-produce preservation, irradiation of research samples for the development of new crop varieties, colour modification of gemstones, development of novel materials and modification of semiconductor properties. An ISO 9001-certified 6 kW electron beam radiation processing facility is fully functional and is operating commercially at Devi Ahilya Bai Holkar Fruit and Vegetable Mandi Complex, Indore. RRCAT has also developed fully home-grown electron beam processing expertise in strict compliance of ISO 11137 as well as AERB and FDA regulations. The radiation processing facility has been providing electron beam for the sterilization of medical devices on a commercial basis. More than 2.5 Million medical devices have been sterilized in this facility. Another 10 MeV, 10 kW industrial linear accelerator has been installed at an industry in Bangalore for industrial scale sterilization of medical devices. RRCAT has already embarked on its efforts to increase the beam power to 15 kW.
4. The Centre is engaged in developing particle accelerators, laser based equipment and related technologies. Will be great if you can list the recent technological developments?
Particle accelerators are very complex machines. Their successful construction requires technologies in a large number of domains like cryogenics, magnetics, ultra-high vacuum technology, radiofrequency engineering, kinematics, metallurgy, precision machining, dissimilar material joining; the list is very long. I will focus on manufacturing technology only while responding to your question.
Manufacturing Technology plays a crucial role in delivering complex and technically challenging products. The 1.8-meter-long linear electron accelerators of radiation processing facilities, made of ultrapure copper, are manufactured at DMTD, starting from raw material to the end product. Engineering marvels like radiofrequency cavities of Microtron, Booster Synchrotron, Indus-1 and Indus-2 are some of the glaring examples of the competence of the Division. This Division has equipped RRCAT to develop recipes for dissimilar bi-material joining of materials like tantalum, niobium, alumina, stainless steel, titanium and its alloys, copper, aluminium and its alloys, molybdenum, aluminium nitride and silicon carbide. It has also developed novel processes in fusion welding of austenitic stainless steels and some non-ferrous metals to meet the design goals emanating from the requirements of particle accelerators. It has developed a completely new technology of making tubular joints between aluminium alloy and austenitic stainless steel.
RRCAT has also developed the capability of manufacturing superconducting radiofrequency cavities made of niobium which are crucial for the development of accelerator-driven sub-critical nuclear power reactors fuelled by thorium. India has enormous reserves of thorium; therefore, this capability will assist in the development of thorium fuelled nuclear power reactors.
The manufacturing technologies developed at RRCAT are also resolving challenges on various other fronts. RRCAT has developed high-power long pulse Nd:YAG lasers of up to 1 kW average power and 20 kW peak power. Laser cutting and welding technology has the advantage of non-contact nature, remote operation, lower heat affected zone, distortion and shrinkage as compared to conventional technologies. Remotely operable laser cutting technology has been developed & deployed successfully for various in-situ operations such as cutting of bellow lips during en-masse coolant channel replacement (EMCCR) campaign, removal of single selected coolant channels for post-irradiation examination for life enhancement studies, cutting of up to 30 mm thick pipelines, etc. for refurbishing and maintenance of Indian nuclear power plants. The use of laser-based technology has resulted in enormous reduction in maintenance shutdown time of reactors as compared to conventional mechanical methods. For societal applications, laser micro-welding technology for I-125 and Ir-192 brachytherapy capsules for cancer treatment and heart pacemaker fabrication have also been developed. Towards the front end of the fuel cycle, laser welding technology for fuel pins has also been successfully developed & deployed.
RRCAT has developed machine vision-based inspection systems to assist fabrication of nuclear fuel. Machine vision system refers to the human-like ability of an intelligent machine with the capability to capture the visual information; decode, analyse it and make interpretations. The machine vision-based system has replaced the human intensive inspection procedures leading to a substantial reduction of radiation exposure. This accurate, non-contact, fast, 24×7, industrial-grade, customized inspection system is a perfect fit for integration into the existing production cycle.
RRCAT’s laser additive manufacturing (LAM) technology for building metallic components stands at the forefront of innovation. RRCAT’s additive manufacturing endeavours have led to the development of cutting-edge LAM systems and metallic components for in-house and industrial applications. The technology is now being commercialized through industry and start-ups. The Centre has also built unique products using cold additive manufacturing technologies like electroforming by electrochemical deposition on removable mandrill or conductivised wax.
5. What is your say on the theme meeting on recent advances in tungsten inert gas (TIG) welding (RATIG-24)? What has been the role of RRCAT towards this advancement?
Recently, RRCAT conducted a one-of-a-kind theme meeting on recent advances in TIG welding of stainless steels, aluminium alloys and titanium alloys (RATIG-24) with the participation of 150 delegates from academia, research labs and industry at one platform. RRCAT felt that although a lot of crucially important and implementable variants of TIG welding are available with research labs, big industries and academia but micro, small and medium sized Indian industries are either not aware or are not confident about the nuances of deploying these emerging technologies. Our theme was Enabling Indian Industries in TIG Welding. The idea of theme meeting in place of a conference was promulgated by the Centre Director Dr S V Nakhe. We split the presentation time and Q&A time in the ratio of 2:1. There were six highly accomplished speakers; two each from industry, academia and research labs. Due to my long experience in technology assimilation and managing changes, I also invited one astoundingly talented psychologist Dr. Ishina Choudhary to give a short talk on role of workplace ethics.
Dr. Supriyo Ganguly of Cranfield University covered the recent trends in TIG welding and introduced many concepts that were completely new to the audience. It has opened doors for new research in TIG welding due to exciting possibilities. Real life examples of hotwire TIG and activated TIG were presented by Dr. Renu Gupta of L&T Mumbai. Dr. M Vasudevan of IGCAR talked about activated TIG welding of titanium alloys. Dr. D K Dwivedi of IIT Roorkee talked about TIG welding of aluminium alloys. Mr. Nimesh Chinoy of Electronic Devices Worldwide Private Limited presented a keyhole TIG welding technique to produce high speed high penetration welding by using high frequency (15 kHz) high current power source. RRCAT presented its technology of nitrogen added TIG welding of austenitic stainless steels.
The sessions were extremely engaging for the delegates as well as the speakers. In depth discussions took place during Q&A sessions, tea breaks and lunch break. The meeting ended with a poolside dinner in a nearby resort.
We are planning for the next theme meeting on 10th January 2025.
6. How does adding a tiny amount of nitrogen in the shield gas immensely benefit stainless steel welds?
Nitrogen is as potent austenite stabiliser as carbon in austenitic stainless steels and is an order superior to nickel in this regard. The weld metal of austenitic stainless steel becomes ferritic due to the requirement of having some ferrite in the weld metal to dissolve the impurities and to prevent hot cracking. If tiny amount of nitrogen is added (1%-3% by volume) in the shield gas then the ferrite – austenite solidification mode does not change. This results in a sound but austenitic weld metal free from hot cracking susceptibility. The nitrogen content of the weld metal depends on the material composition but it is expected in the range of 0.12% to 0.22% by weight for type 316L when the shield gas contains 1.5% – 2% nitrogen by volume.
The ferrite converts to sigma phase at moderately raised temperatures during stress relieving / post weld heat treatment and the weld may become vulnerable to rapid loss of corrosion resistance. Ferrite can cause a sharp decrease in corrosion resistance in hot oxidizing media in molybdenum-bearing grades like SS316, SS316L, SS317 and SS317L. Therefore, certain applications such as manufacture of urea requires the weld metal to be nearly fully austenitic. In addition, the welds are also the most vulnerable locations for localised corrosion. Addition of nitrogen protects the weld metal due to increase in its pitting resistance equivalent number (PREN).
Indira Gandhi Centre for Atomic Research has done a lot of research on fatigue and creep resistance of austenitic stainless steel by increasing the nitrogen content of the material. They have shown that nitrogen content 0.12% – 0.14% by weight gives the best low cycle fatigue resistance and there is a monotonic increase in creep resistance below 500℃ when the nitrogen content is increased.
In cryogenic applications, the low temperature impact strength decreases with increasing ferrite content; therefore austenitic weld metal may be more suitable.
In all the above cases, the service life of the pressure equipment can be increased tremendously just by adding tiny amounts of nitrogen in the weld metal.
For many magnetically sensitive applications like directional oil well drilling and ultrahigh vacuum chambers of particle accelerators, addition of nitrogen in the weld metal helps in getting a low and homogeneous relative magnetic permeability throughout the material boundary.
7. What is your say on the current market scenario of R&D segment in India? Is it on par with the international market? What are your expectations?
We have to go a long way. The major difference between India and the developed nations is that their industry is accustomed to take up challenges of doing developmental and inventive works whereas a very small number of Indian industries are in that frame. However, I can proudly say that the country has really changed over the years. The confidence levels at the research labs are highly elevated. Scientists are eager to take up challenging tasks and deliver the products. The industry is more positive towards taking up developmental or even inventive jobs.
Recently, I interacted with a few small industries and was surprised at the confidence levels and their willingness to take up tough engineering challenges. We are also quite eager to work in tandem with industries so that our conforming products are delivered by them in time.
The manufacturing industries must invest in creating permanent and substantial R&D teams with a long term vision of doing cutting edge research. It is necessary that an organisation does the R&D on a continuous basis. This defines the culture at the organisation.
The “Make in India” and “Atmanirbhar Bharat” push has helped in changing the mind set of research labs as well as the industries. Many products that were imported earlier are being manufactured indigenously.
The results are not on similar lines when we look at new products or processes. There is a need to improve the quality of undergraduate technical education. Conversion of a creative idea into a new physical product or process requires very sharp conceptual understanding at the fundamental level. The concept of empirical creativity does not work otherwise. The academia must work closely with industry and research labs by going outside their comfort zones so that these real life experiences are also transferred to the students.
There is no better learning experience than delivering a new product or technology that meets the expectation of its user. Fortunately, the country has a large pool of highly accomplished engineers from research labs who have made several challenging one-of-a-kind deliveries in their service time. We must engage them as visiting faculty in academia and consultants in industry. UGC has taken some step in this direction by proposing Professor of Practice posts but there is a long way to go.
Department of Atomic Energy has devised a superb process to rigorously train the technocrats at three levels – 2 years full time stipendiary training for ITI pass outs, 2 year full time stipendiary training for engineering diploma holders and science graduates, and 1 year full time full time training for engineering graduates and science postgraduates. This model is worth emulating for Indian industry.
8. How according to you the country’s research output can become useful to the technology hungry Indian industry?
The technologies and products developed at research labs for specific applications are transferred to the Indian industries and start-ups under their incubation programmes. For example, AIC RRCAT π-Hub Foundation, a Section-8 company under DAE is mandated to translate technologies, know-how, and expertise developed at RRCAT into products or processes for the Indian industries or start-ups with the seamless handholding of RRCAT scientists and engineers. The scientists at the research labs are eager to engage in such endeavours although it also becomes tough on them at times due to their commitments to the project deadlines. Many of the technologies and products developed at RRCAT have been transferred or are being transferred to the Indian industry through various modes of incubation.
I also believe that instead of having extravagant conferences; there should be one or two day’s theme meetings on very specific and relevant topics where small number of technocrats from local industries could participate at minimal expenditure. This will be opportunity for smaller industries to learn from the best in the world of academia, research labs and big industries. Unless we uplift the level of smaller industries in manufacturing sector, we won’t be able to change the nation’s technological standings. RATIG-24 was a massively successful beginning in this direction. We expect other R&D units to follow the path and contribute to the cause of nation building.
9. Please elaborate on the idea of Centre of Excellence in Advanced Manufacturing as well as AI and ML driven TIG welding.
It has been collective experience of RRCAT that mere knowledge of a joining process is not enough to build products. The product also brings a lot of uncertainties due to additional constraints brought by weight, volume, size, shape, thickness, material etc. Also, high productivity welding processes like keyhole TIG and activated TIG welding require automation. A considerable time and effort must be invested in detailing the joining process that will exactly meet the requirements. At times, the designers do not understand this gap as well as the need of developmental efforts and expect a delivery of a conforming product within the project’s time frame. Centre of Excellence in Advanced Manufacturing will work on such problems and solve them without affecting the project schedules. At times, we also come across situation where there is a joining requirement but there is no existing solution at all. In such cases, CoE will take up inventive problem solving.
Over a period of time, the personnel engaged with such endeavours would gain expertise and experience which will further aid in reducing the development time. At present, the scenario is quite different. These problems are very specific and the solutions are also quite unique. The project teams or the conventional manufacturing teams are not mandated to create a knowledge bank and preserve the experience after solution of these onetime problems. However, CoE would solve such problems on a regular basis; therefore it would develop expert human resources who would continuously learn from each experience.
It is possible to ensure welding quality by altering welding parameters in real time using AI. Getting full penetration TIG welding, particularly in high penetration variants like activated TIG welding or keyhole TIG welding, is a challenge; therefore a way of online penetration recognition is necessary. Convolution neural network, based on time-frequency image calculated from arc-sound signals, have been deployed in TIG welding of aluminium alloy with better than 98% penetration recognition efficiency in a research work. The arc-voltage variation can also tell a lot about the state of full melting. Analysis of characteristic signal power spectrum signals between 36 kHz and 37 kHz in keyhole TIG welding of type 304 stainless steel can reveal the state of complete penetration. The industry would benefit a lot if these works are taken up for deployment. The CoE would work in these directions also as multi-disciplinary support is available within RRCAT. Board of Research in Nuclear Sciences also sanctions grants against meritorious research proposals coming from academic institutes and industry with DSIR approved research labs. This route will also be utilised to take this work to the next level.
10. RRCAT has developed vacuum brazing recipes for dissimilar material joining of materials like tantalum, niobium, alumina, etc. Please brief us more?
Particle accelerators are one of the most complicated machines built by mankind. Design and Manufacturing Technology Division of RRCAT caters to the extremely challenging needs of design and manufacturing of components of these particle accelerators. A variety of materials are required in these machines due to their specific properties. These material must be joined to their conventional counterparts with a joint quality that is compatible with the machine’s ultra-high vacuum envelope. Generally dissimilar material joints and thick copper to copper joints are very difficult or at times impossible to make with fusion welding techniques. Torch brazing cannot be deployed for ultra-high vacuum components as they contain volatile flux residue as well as flux voids, both of which can act as virtual leaks. This leaves vacuum brazing as the only viable option. As the base metals do not melt in brazing, their relative differential expansion and contractions pay a major role in the success of the joints. Finite element based structural simulations help a lot in understanding of these effects. Apart of this, the selection of braze filler metal and brazing cycle parameters are crucially important. We started this journey a decade ago. Initially the journey was full of setbacks (we call it learnings) but due to our relentless efforts, we have now developed a lot of recipes and a lot of confidence to take any new developmental assignment.
11. Availability of skilled technical manpower is one of the major challenge in India. How can we manage to cope up with the same?
In 2018, I proposed implementation of a scheme called TASAR (Trade Apprenticeship Scheme at RRCAT). We provide 1 year practical training to ITI pass young boys and girls by engaging them in our day to day activities. So far, we have trained 200 apprentices in this scheme and 80 are undergoing the training programme. This scheme has been extremely useful in creating a pool of highly skilled technical manpower for the country. This scheme has also benefited RRCAT as these apprentices do a lot of work while they are being trained. RRCAT management has also recognised the benefits; therefore a girls’ hostel has been made operational recently and the boys’ hostel is also under advanced stages of completion.
In my opinion, this scheme has a lot of potential in creating a pool of highly skilled technical manpower in every field, not only welding. The industry should take keen interest in implementing the scheme. It is very simple and effective and it can be started with minimum initial investment.
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Mr. Abhay Kumar graduated in mechanical engineering from Muzaffarpur Institute of Technology in 1992 and immediately joined 36th batch of BARC training school for one year orientation program in nuclear science and engineering. After completion of this post graduate program, he opted to join Raja Ramanna Centre for Advanced Technology as this was new institute and offered challenges of building big particle accelerators for the first time in the country.
He started his professional journey in the field of engineering computations in structural, fluid, heat transfer, electromagnetics and coupled physics domains. As the purpose of the computations used to be evolution of new products for specific applications, he made a natural progression into new product design and made several distinguished contributions in development of particle accelerators like Microtron, booster synchrotron, Indus-1 and Indus-2 synchrotrons, linear accelerators at RRCAT and Large Hadron Collider at CERN.
He has pioneered the work on vacuum brazing at RRCAT. He developed indigenous ultraclean vacuum brazing furnace in 2014. He has developed a strong vacuum brazing team at the Centre. He is now leading Design & Manufacturing Technology Division of RRCAT.
He has 20 journal publications, 65 conference presentations and has bagged several awards in IIW conferences.
