Fassi Approved Manufacturing – Fassi Cranes
“FASSI APPROVED” MANUFACTURING PROCESSES – A TRIP ALONG THE CASTING AND WELDING CYCLE
Among the characteristics that distinguish a Fassi crane on the market there is certainly a special commitment to quality in every technological and constructional aspect, which takes concrete form in machining processes that are perfected directly within the company. These are the fruit of exclusive know-how from the sector, and the results are only approved if they comply with the severe expectations set for each phase. Among the fundamental points in this commitment is the choice and processing of metals, and in particular special steels, which are selected and processed so as to form a true production cycle, with levels of excellence that deserve to be more widely known Let us now take a look at some of the attention dedicated by Fassi to metals, as they are gradually transformed from “raw material” into a crane: casting and welding processes, bearing in mind that these too are required to comply with precise and extremely strict quality parameters, rigorously tested and checked, so that each individual piece is “approved” by Fassi.
Casting of bases and columns
The crane bases and columns is an excellent example of how Fassi approval is applied and what it involves. Cast elements are made from special steel and cast iron, and many have extremely high mechanical characteristics, comparable with those of metal sheets with high elastic limits. The majority of the alloys used in casting are defined directly by Fassi, in co-operation with specialists in these processes. The entire casting system of potential suppliers is analyzed by Fassi technicians, and only if considered capable of respecting and providing a long term guarantee for specifications, in terms of all casting characteristics (chemical, mechanical tenacity, health and safety…) will the foundry be “Fassi approved”. Fassi’s know-how is also of fundamental importance to discriminate between, and thus provide an objective evaluation of, the methods used by the supplier, from casting procedures to forming (empty form created from sand/resin which is filled with the molten metal during the casting process), to the various finishing operations, to heat treatment and nondestructive and laboratory testing. According to the methods used the results obtained may be quite different, and over the years Fassi has identified and perfected which of these parameters are ideal. Again bearing in mind that excellence means first of all preventing the faults typical of casting (such as cracks, inclusion of foreign bodies, shrinkage, bubbles…), the processes are approved casting by casting, with an extremely wide-ranging series of tests. These start from sectioning of prototypes and continue with a range of non destructive tests (control using magnetic particles, penetrating fluids, ultrasound, rays) in search of possible internal and surface faults. It then proceeds with analysis of material characteristics (chemical analysis, metal analysis, hardness tests, traction tests, resilience tests…). Each single casting is only approved if all the test results comply with Fassi specifications. All this commitment is justified by the target that Fassi has set itself: using monolithic cast components it is possible to obtain the ideally shaped base, column and other components, according to the stress to which the crane will be subjected. This makes it possible to achieve levels of reliability, particularly in the long term, that would be impossible using welded components. This is why Fassi has adopted cast elements in almost all its products.
The welding process
It is clear that the characteristics and end quality of welding operations also depend first of all from the materials to be welded together: this is why Fassi makes a careful selection of the suppliers of special steels. The secret of a perfect weld then depends on setting the process parameters exactly: Fassi uses a continuous semiautomatic, automatic and robot controlled “mig mag” gas arc-welding process (using active-inert gas) which, because of the types of material and thicknesses involved, reduces the faults typically found in other types of welding processes. All those machining operations and actions carried out before welding, such as preparation of the parts and study and creation of specific equipment and systems to position and lock the edges to be joined, also fall within the company’s range of activities. Equally important is the choice and definition of welding parameters, such as electrical parameters (volts, amps), the speed of advance of the welding torch and the solder, the movement of the torch, the distance between the torch and the piece. But equally important are the gas type and flow rate, and the type of solder used, according to the materials to be joined and the type of joint. The delicate nature of this process and the exclusiveness of the Fassi procedure lies in setting out all these parameters, on which the end result depends, in the ideal way. It is also of fundamental importance for specialist technicians to carry out inspections during the operation, to ensure that the parameters set in the procedures are complied with and to carry out non destructive and laboratory tests for continuous process monitoring. The aim is to guarantee the required quality in terms of the shape, size, resistance and tenacity of each joint.
Once the steel casting (in the case of cast iron the process is different) has been broken out of the mould and flogged, it is freed from the feedheads and casting channels and subjected to an annealing process. At this point the non destructive tests on each individual raw component begin: using magnetic particles, penetrating fluids, ultrasound and X-ray. After any repairs (only foreseen for steel castings) the raw component is then subjected to thermal treatment cycles, which may be for normalization or tempering and hardening, to give the piece the mechanical characteristics and resistance required by Fassi specifications. After these operations, final tests are carried out both on the pieces and on the samples. The samples are normally tail elements that are cast with the pieces, and therefore undergo the same cycle. At the end these tail elements are cut away from the casting, and the samples taken in this way are used to carry out the traction, resilience and metal analysis tests to ensure that the material complies with the necessary specifications.
In Fassi, welding is mainly carried out using very high technology automatic and robot controlled systems, capable of ensuring perfect replication of the parameters foreseen by the process. Whether it is done by a robot or by a specialist welder, they are still an integral part of the Fassi “approval” process. This means that both the technicians programming and managing the systems and the welders themselves are suitably trained and qualified to comply with the process requirements that characterize work here in Fassi, whatever the conditions.