Since late 2004, BRUNO VENTURI S.p.A., Italian importer of high resistance Weldox and anti-wear Hardox steels, produced by SSAB, the Swedish steel mill, installed Explorer, the laser cutting system produced by Promotec, for high precision cutting of large sized formats. Thanks to the laser system, the company can offer customers a new type of cutting, on top of the existing oxygen lance cutting, and plasma cutting. The company supplies customers pre-worked pieces (cut, bent and chamfered), ready for direct use in the final product construction processes.

Supplying elements of a modern Industrial meccano
There is a long-standing belief whereby the profitability of a laser cutting system for flat sheets is essentially linked to the possibility of this work process satisfying customers’ requirements. That is why, it is considered that a laser sub-supply centre has a better chance of operating under market conditions when it is able to supply its customers with a complete product, rather than a simple piece of cut sheet. There is no doubt that this is a generally well-founded statement, irrespective of the type of centre. However, I had never encountered the specific situation of a company importing special steel sheets.
Therefore, in this article, I wish to present my experience at the BRUNO VENTURI S.p.A. company, Italian importer of high resistance steels Weldox and anti-wear Hardox, produced by SSAB. As we shall see, in this case too, the company’s success is linked to the possibility of supplying its customers with worked pieces of sheet (cut, bent, and chamfered), rather than simple flat sheets.

They offer greater resistance for equal thickness
At the company I met the proprietor and chairman, Mr Bruno Venturi, who asked his daughter Federica to joins us - she is a director of the company.
“For thirty years now, this company has been transforming high resistance anti-wear sheets produced by SSAB, the Swedish steel mill” Mr Venturi explained. “To fully understand the situation of the company which I set up long ago in 1955, we must underline two fundamental aspects: the type of materials we import and the fact that we are not resellers of raw sheets, but actually convert the sheets we sell. “ To better illustrate the first aspect, instead of making a lot of general comments, one can put forward a banal but concrete example: if high-resistance steels had already been available when the Eiffel Tower was built, for an equal weight, the tower could have been three times larger, or for an equal height, three times lighter. This is due to the fact that this type of steel, for an equal thickness, has greater resistance (almost factor three) compared to traditional carbon steels”.

In fact, the Weldox steel brochure states that: “Flat blooms coming out of the continuous casting, are uniformly heated at a temperature of 1,200 ° C, to enable lamination by means of the fourth reversible mill. The sheets are then air cooled, hardened and are then subjected to final hardening and tempering entailing cooling b atomised water from 900°C to ambient temperature. In this way, the Weldox sheet, with low equivalent carbon content, acquires uniform high yield resistance (over1,100 N/mm2), good impact strength and excellent workability, even on machine tools”.
“This steel is increasingly acquiring the characteristics essential for all structural uses where high resistance, combined with a light structure are required. We are, in particular, referring to transport, earth handling or lifting machines. Clearly, the lower the weight of the machine, the greater the weight of the transported or handled material” Mr Venturi explained.

Suppliers of the elements of a modern industrial Meccano
The Hardox anti-wear sheets instead satisfy the severest demands as regards resistance to wear/abrasion, because they combine strength and a high level of hardness, extremely high yield stress resistance and excellent tenacity. These characteristics make the product decidedly suitable for a multiplicity of applications. Although Hardox sheets are 3 to 4 times harder than ordinary high yield resistance structural sheets, their excellent on machine-tool weldability and workability characteristics make them readily usable in very many applications.
“This type of sheet - explained Mr Venturi - was introduced over 50 years ago and was initially produced by American mills under the name T1. It was also produced by the Genoese plants of ILVA, which wee subsequently dismantled due to lack of foresight. We now depend on the Swedish supplies, whose producers can operate in an almost monopolistic situation. This is where the BRUNO VENTURI company comes into play. It has two important characteristics: a large warehouse, and the equipment required to convert the sheets into pre-worked pieces (cut, bent and chamfered), ready for direct use in the construction processes of the final product. “Thanks to our warehouse, which is restocked every month to cover all qualities an thickness values - explained Mr Venturi - we can immediately satisfy all our customers’ requests, so that they do not have to wait a long time for the steel mill to prepare the material. Furthermore, I must stress that we do not sell cloth to tailors, but offer them cut-to-measure pieces that only require sowing. To give you another example, we can say we are suppliers of the elements of a modern industrial Meccano (our motto is: “We transform your ideas”), whose pieces must then be composed by the producer to arrive at the final product. These are the two main characteristics that have enabled us to grow continuously all the way to our current size, with over 45 employees.

The most important applications can be found in earth handling machines
“A big step forward compared to fifty or so years ago when our company was set up. It then traded in scrap iron and re-usable iron metallurgy materials” said Ms Federica. We asked her to tell us about the main use sectors for these sheets. “The main applications are in the field of earth handling machines (excavators, crushers, buckets) and lifting machines (cranes, crane-trucks, and telescopic arms), agricultural units (plough-shares, mouldboards, chassis, and ploughs), industrial vehicles (axles, chassis, unloading units, dumpers, and bodies), pincers for crushing, presses for squashing….Well, that’s a whole lot of different applications”.
I mentioned that an old brochure I picked up on a visit to the Samoter fair, also described the company’s possibility of operating in the tubes and rods sectors in general. Ms Federica answered this promptly: “We had this operating possibility up to 1995. That year we decided to stop all other activities in order to concentrate on the sheet transformation sector. We had for some time been thinking of investing our resources in another type of technologically more advanced heat cutting: plasma cutting. To reach our objective, we needed space to install our machines. The result of our reasoning was almost obvious: eliminating the tubes and rods meant freeing the space required for two plasma cutting machines. In the same period, we were approaching the EN ISO 9002 Quality System certification, according to which the tracing of raw materials had to be guaranteed. This second motivation highlights the characteristics of our company: in the tubes and rods sector, you’ve got to work mainly with stock products with uncertain characteristics. We therefore preferred to work with certified sheets, whose characteristics we could guarantee to our customers. Ten years after, we do not regret this choice, because operating in a quality scheme is always a trump card”.

A system heading for the big cutters market
We shall not, of course, dwell on describing traditional machines, and will leave it to the figures to illustrate the produced parts, which, at the time of my visit, mainly concerned crane arms or bodies of earth handling machines. Instead, with the help of Mr Marcato, an engineering expert and managing director of Promotec, the construction company, we shall describe a few details of Explorer, a machine for laser cutting large format sheets.
“Explorer is a laser machine based on a highly innovative concept. It is a system aimed at the big cutters market. It can be configured for different possibilities of X transverse useful strokes (2,600 3,100 4,100 and 5,100 mm) and Y length on request, using 3 m modules for strokes from 6 m up to a maximum of 42m.
In the example installed by BRUNO VENTURI S.p.a. the X transverse useful stroke is 3 m, and the Y stroke is 30 m. An essential characteristic of this large machine is the possibility of adapting to the planarity conditions of the customers’ sheds, even if, both the rails and the floor are not perfectly level. Therefore, no building work to modify the floor in order to install the system, is necessary: all that is needed is an industrial floor comprising 20 cm of concrete, with double metal netting and good planarity”.

The biggest problem to solve is positioning the travel ways
There are two important characteristics in the system installed in the new shed of BRUNO VENTURI S.p.A: the on-board machine laser generator is not installed on the cross-beam, but on a lateral structure; an X1 local axis is provided for quick movement of the focussing head.
“Explorer was designed to use, as standard items, different CO2 laser generators according to the customer’s requirements” Mr Marcato explained. “These are the generators: Rofin series DC (for power values from 2.5 to 3.5 kW ), Trumpf series TLF (with power values from 3.2 to 5 kW) and Fanuc (with power values from 3 to 6 kW). To do this, the system had to be flexible to accept the different types. The alternative was to make three different structures of the cross-beam, suitable for the three different sources, but this could hardly be suggested”. Furthermore, we should add that the system installed by BRUNO VENTURI S.p.A has a 3.5 kw Rofin DC035 source.
“Additionally, the possibility of having a local axis, makes it possible to obtain a high level dynamic in executing small cutting strokes, as, for example, when making holes with a diameter of up to 100 mm” Mr Marcato explained. “In this case, the software automatically defines which X or X1 axis is most convenient for the work cycle. In this way, all strokes closed with an X smaller than or equal to 100 mm are performed by using axes X1 and Y. If, on the other hand, the value of X is greater than 100 mm, the X and Y axes are used instead. This technical choice makes it possible to considerably reduce cycle times (because one can operate at a faster work speed), to optimise results (through the greater precision available) and to reduce the machine’s overall ‘fatigue’ “. But how did you solve the problem of stability during the time required to correctly position the travel ways? “ The major problem to be solved in installing a laser cutting machine capable of operating on large dimensions, is positioning the travel ways while respecting three basic principles: parallelism, coplanarity, and verticality. To guarantee these characteristics, one would have to build a foundation plinth with dimensions equal to the width and length of the two rails. In addition to its high cost, a plinth would not, in any event, guarantee the necessary characteristics long term. To avoid this costly operation, a system for automatically levelling the machine was successfully designed and patented. With this system, the machine can move at the necessary degree of precision, irrespective of whether the rails meet the three conditions we described above. To overcome the lack of rail parallelism, something which can happen through time, one of the transfer shoulders was made to float. It was installed on linear guides which move transversally with respect to the movement along the Y axis. This system not only makes it possible to overcome any yielding of the floor, but also to provide a higher margin of tolerance when the rails are laid. With this solution, it can easily be seen that, if the rails are not parallel to each other, the system can nevertheless adapt to the new situation. The important thing is that the Master rail should be periodically maintained and controlled, checking its straightness long term”. Our compliments go to Mr Marcato for his new technical idea and to BRUNO VENTURI S.p.A skilful tailors of high resistance sheets.

Many thanks to Bruno Venturi Spa from Verona (Italy) Mr. Bruno Venturi