Published on 04/02/2021
Alma started to explore the world of shipbuilding in 1982. At that time, the Chantiers de l’Atlantique shipyard at Saint-Nazaire was looking for a solution to minimize its material losses. Bearing in mind the tonnes of steel used to build a cruise liner, this represented savings that would be more than substantial. Alma had just been created, with the aim of promoting to industry the automatic nesting algorithms developed as part of a research project at the University of Grenoble. This was the starting point not only for our long-standing collaboration with the Saint-Nazaire shipyard, but also for development and deployment of our Cutting CAD/CAM software for shipbuilding right around the world. Today this software enables us to meet every specific shipbuilding need, and to be recognized as the major player in shipbuilding CAD/CAM applied to sheet metal working.
Apart from the need for good automatic nesting algorithms, what are the specifics relating to the shipbuilding industry? Or to put it another way, what are the characteristics of good shipbuilding CAD/CAM software? There are several answers to that question.
It should take into account the way a ship is built
First of all, it is important to understand how ships are built, because that determines the data (parts to cut, stock of sheets and offcuts). A ship is made up of blocks, progressively assembled starting from the middle, to achieve good balance. Each block consists of sub-assemblies, which in turn consist of floors and walls. So it is usually recommended to organize the data in blocks, to avoid mixing up parts from different blocks in the same nesting layouts. It is important not to complicate the logistics, which are already very demanding, and to simplify sorting of the cut parts so they can be sent to the sub-assemblies where they must be welded. Similarly, the material needs, which are often calculated before completing the detailed design of the ship, based on the initial versions of the parts resulting from the CAD, will be used to define the stocks of sheets necessary for each block, bearing in mind that recoverable offcuts can sometimes be transferred from one block to another.
It should retrieve the geometric and machining data
For our first shipbuilding projects we started by defining a neutral format for data exchange with the CAD. Then as time went by we developed interfaces with every system in the field, so that today we can work with any shipyard no matter which CAD it has chosen to use. We import the geometries describing the parts to cut, if necessary separating them in the case of a multi-part DXF, and we retrieve all the most commonly used machining data. These data may be the different marking and grinding processes, the wide variety of texts indicating the name of the stiffeners to weld, the ship axes, the folding lines, the chamfer properties applied to each edge, etc. It is worth noting however that when deploying our solution, in addition to importing the geometry and machining characterizing a part, it is almost always necessary to adapt the process for importing and exporting the parts to cut to the shipyard’s operating process. For example, how should part modifications be managed? Is it necessary to systematically invalidate the nesting layouts impacted by a modified part, or is better to allow the user to do so?
It should completely master plasma cutting, cutting of chamfers and marking
Any shipbuilding CAD/CAM solution has to take account of the specificities associated with the industry and the most popular machines. It is therefore particularly vital to master plasma cutting (the most frequently used technique due to the thickness of the sheets to cut). So among the most frequently used functionalities, we will find continuous cutting (bridged parts to minimize the number of lead-ins and therefore machining time), management of plate straps (leaving certain openings attached to the part for transportation requirements), and cutting of the skeleton (to evacuate it more easily). In the shipbuilding business it is also necessary to have the capacity to manage machines that produce chamfers, and to manage the associated operations (multi-passes, height verification, reconfiguration loops, etc.) as well as specific marking units. In particular these operations make it possible to trace all kinds of texts which are used for assembling or welding the parts.
It should manage (very) special machines
But the biggest contributing factor to our success in shipbuilding is our capability to manage special machines. To do this we offer a sufficiently open solution, enabling you to use the basic functionalities of the CAD/CAM software to develop completely customized applications. For example, we manage lines of “flat panel” machines. These machines assemble and weld sheets to then cut out a particularly large part constituting a deck of the ship, and ultimately, weld the sections or stiffeners ensuring it is rigid and perfectly flat. The machine used to carry out cutting can also be used to perform other operations such as grinding, marking, text tracing and chamfering. Another example of the special machines that our software manages are “symmetrical” machines. Certain symmetrical machines can simultaneously mark/cut port and starboard parts that are “virtually” identical. Others are “asynchronous double head” machines that can cut the top and bottom of the same part simultaneously without the cut edges being exactly parallel.
It should automate software functioning
One distinguishing feature of shipbuilding is the huge quantity and variety of parts that need to be nested and cut. This enables us to hone our automatic nesting algorithms, and more generally requires their functioning to be as automated as possible to reduce programming times and the risks of error. Accordingly the vast majority of the solutions we deploy are organized around the following phases, performed and sequenced automatically: import of parts with preparation of machining, creation of start-up orders (grouping by material/thickness/block), nesting and generation of the NC files in batch mode. In one last optional phase the start-up orders are closed in order to declare the cut parts and make available the off-cuts generated by the nesting layouts. It is also important to note that the documents automatically made available to the machine operators and programmers are almost always customized, in particular to meet the need to identify the cut parts and facilitate sorting.
It should manage the linear cutting and robotic welding processes
As already mentioned, a ship consists of sheets and sections assembled by welding, in which the main purpose of the sections is to stiffen the ship’s structure. The cables and pipes are positioned in the sub-assemblies or blocks. The interior fittings are installed as early as possible, but after assembly of the first blocks. In this process, our software is deployed not only to nest and cut parts from sheets, but also to optimize cutting of the sections. As a result we have developed various section nesting algorithms to maximize use of the raw material bars, while meeting the requirements imposed by the machines that we manage (saws or robots). In addition, to complete our know-how we are exploring welding issues linked specifically to shipbuilding. Our Almacam Weld software comprises numerous functionalities for automatic geometric recognition of 3D shapes and generation of welding tasks, enabling us to meet the off-line programming needs of welding robots.
It should have a strong partnership-based approach and the ambition to provide service right around the world
Above and beyond the technical capabilities of our software solutions, Alma’s reputation is the result of the skills acquired over the years thanks to trust-based relationships with our customers and solid partnerships with different players in the shipbuilding world, in particular vendors of CAD/PLM solutions. This expertise has been gradually acquired over a period of nearly 40 years and has been disseminated to all the sales and technical teams in our network. It enables us to tackle any shipbuilding project in the world with confidence and peace of mind, because we are fully familiar not only with the general issues raised by shipbuilding, but also with the specificities associated with different types of ships or the location of the shipyard. We work with the largest European builders of cruise liners, and we provide equipment to many builders of military vessels and cargo transportation ships, right around the world (Brazil, USA, France, Italy, Germany, China, India, Indonesia, Korea, Japan, etc.).
Finally, we are counting on our new range of Almacam products to bring our customers even greater added value. This new release will be available to ship-builders within a year. In particular it will bring complete traceability of manufacturing, a functionality that has become vital in order to manage the Quality processes implemented nowadays.