In the summer of 2020, the Shiprepairing Center «Zvyozdochka» a pilot laser metal deposition plant, developed by the Institute of Laser and Welding Technologies at the St. Petersburg State Maritime Technical University (SPbGMTU) as part of the federal target program "Research and Development in Priority Areas for Russian Science and Technology Sector in 2014-2020". The shipyard has already been visited by camera crews from local, regional and federal TV channels. Journalists asked how this device, which is essentially a 3D printer, works. We asked people directly involved in the introduction of the new plant, designed for direct laser deposition of marine engineering parts, to tell us about the novelty.
Deputy General Director –Head of the Center for PropulsionSystems:
Modern technologies are evolving all over the world and Zvyozdochka is not lagging behind.In 2017, we became an industrial partner of the St. Petersburg State Marine Technical University and allocated 60 million rubles for developing a pilot plant. The key participant of the project was the Ministry of Science and Higher Education of Russia, which provided the university with a federal subsidy. This cooperation has become a new form of relations between enterprises and institutions, providing support for our science and assured the application of scientific developments in production. The plant, together with the technology of its application, was the first evidence of the effectiveness of such cooperation.
The equipment was delivered to the Center of Propulsion Systems (CPS) last year, the plant is already running and pilot testing is underway. This area of technology is certainly new not only for us, but also for the entire domestic shipbuilding industry. There are no ready-made solutions here yet.
Our specialists are testing various types of powders. We receive prototypes in the form of small plates and give them to the central laboratory of the enterprise. These have to undergo a set of tests and studies, so that later we can focus on a certain type of powder, temperature and other process parameters when producing metal parts.
After receiving these results, we’ll start manufacturing tooling and fixtures. We cannot immediately switch to standard products, although we have already carried out studies and even decided on a specific order. If we achieve the required parameters on the prototypes, a decision will be taken to use the products on standard structures. We plan to use them primarily on podded propulsors and thrusters. The latter include a lot of components and systems, where we will certainly find application for parts manufactured using the new technology.
Chief Engineer at the Center for Propulsion Systems:
The direct laser deposition process is layer-by-layer deposition of metal in the form of a powder that is melted above the part surface by a focused energy source, a laser beam. To implement this technology, an 8-axis direct laser deposition system is used. Complex parts are made using a robot manipulator and a 2-axis work table. The plant is capable of producing parts of 1300 mm in diameter, 500 mm in height and weighing up to 250 kg from various metals.
The main advantages of laser metal deposition on this plant over other additive manufacturing methods are the capability to produce sufficiently large parts and blanks of complex geometry, as well as a wide range of powder metal materials used: alloyed and stainless steels, titanium-based alloys, etc.
In traditional mechanical engineering, parts are made from blanks (castings, forgings, and rolled products). The use of the direct laser deposition method significantly reduces the allowances, thus cutting the final machining time for a product and significantly reducing its production man-hours. In addition, we produce a work-piece ourselves and can create a very complex shape that cannot be provided by traditional methods.
The new technology ensures also part weight optimization. Often there is a desire to reduce the weight of a part at the expense of its portion that «doesn’t work». This portion is usually located inside the part. With our know-how, this can be achieved by making the “internals” of the part in the form of a mesh, honeycomb structure, or even hollow.
Finally, the additive technology makes it possible to repair and recondition marine engineering parts by laser powder surfacing.
Set-up and test engineer:
This is a completely new and very interesting process. I’ve never seen anything like this before. Since it is a pilot plant, difficult issues arise sometimes that need to be solved quickly. All the process parameters that the developer provided us with are approximate. They need to be fine-tuned. However, unlike the laboratory, it is very important at a manufacturing site to quickly manufacture defect-free parts.
So far, we are designing and making quite simple models by selecting various parameters and varying them to achieve the required indicators. Then we’ll move to complex shape parts.
Despite the robotization, the human factor is still at the forefront. A machine does what we program. Accordingly, the final result depends on our minds. There are two ways for writing programs: either in the programming and modeling environment, or directly from the plant control panel. So far, we are using remote control, because this allows us to vary the parameters in a wider range. We experiment, analyze the result, make changes to the process parameters or accept them.
It takes half an hour to produce simple parts, such as prototype plates. In the case of complex and large-sized parts, the machine may work continuously for about a hundred hours, that is, more than a week. This is absolutely normal practice. The plant is ready for this mode. Only the operator who controls the process is replaced. Two specialists are enough to directly operate the plant. We are already training people. In addition to the operator, engineers and programmers work on each product. I can’t say yet that we can do everything. The process of mastering the new equipment is still underway. We’re honing, honing and honing our skills.
Photo by Mars Biktimirov
Between 2011 and 2020, the Nevskoe Design Bureau carried out a number of outstanding projects, including the aircraft carrier Vikramaditya for the Republic of India