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| DESIGN AND RESEARCH - |
Technology and attractive design travel at the same speed. Since 1994 O·Z has had its own Style Center, which is closely connected with the Research and Development Department. A closely-knit group of designers, engineers and technicians combine skills acquired in the field of design with experience and professionalism coming from racing teams. Designers and professionals are selected from specialized schools, to the point that precisely in 2002 O·Z drew up an agreement with the Espera training centre, run by the Swiss-Italian designer, Franco Sbarro. Fashion, trends, attractive looks and constant attention to new technology blend happily together in O·Z projects, to guarantee the same quality standards in the final product as those requested by driving champions.
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Drawings on paper, drawn up by the creative staff in the Style Center are transferred using sophisticated CAS-CAE technology to a computer simulator which carries out structural tests on the design using Finite Element Analysis (FEA). Lines of force, the mechanical response of materials and appearance are analysed on 3D models and undergo tests by specialised staff. At this stage close co-operation between designers and technicians becomes crucial.
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| PRODUCTION - |
Starting with the mathematics of the wheel model provided by the computer, the steel mold destined for the casting department is developed. The aluminium alloy is brought to a temperature of about 700°C and is cast in molds using gravity or low pressure, according to the type of wheel to be produced. In this way a "rough" wheel is obtained, ready for mechanical machining. |
| Immediately after casting, the wheel undergoes heat treatment, which improves the mechanical and physical features of the alloy. |
| Precision is of the utmost importance in the O·Z workshop where wheels are milled, turned and bored. The profile of the rim, ribbing, disc, centring and the holes for bolting to the hub are machined on precision equipment which enables the strict tolerances required to produce a top-quality product to be achieved. |
The wheel at this stage passes on to the painting department. It is painted with epoxy powders and then with a metallic finish. As an alternative to painting, forged aluminium wheels are anodized using a special electro-chemical treatment.
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O·Z has its own research and development department equipped with sophisticated analysis and planning information
technology systems, which improve production standards and drastically reduce time-to-market. Classic CAD and CAM programmes are supported by CAE
(Computer Aided Engineering) stations, which provide simulation of the physical responses of the wheel on the sole basis of a virtual CAD
geometric model. Specific software, based on FEA codes (Finite Element Analysis) enables the geometric shape and choice of materials to be optimized
and the critical factors of the product to be identified by virtually simulating a physical or mechanical problem. Times and costs of laboratory tests
are therefore reduced. Predictive engineering is also supported by RP (Rapid Prototyping) technology, which enables physical prototypes to be
constructed in very little time directly from data provided by the CAD virtual model. The steel mold with which the casting or forging machine is equipped
derives from the resin matrix, constructed using Rapid Prototyping.
Casting and forging: two modern foundry technologies for two different categories of product. The first is used principally in the production of wheels
destined for the after market, and therefore large series, offering however the style, design and state-of-the-art technological solutions which
characterize racing wheels.
Forging follows a production procedure which is substantially different, and enhances the physical and mechanical qualities of alloys, making them
suitable for use in competitions. Aluminium or magnesium alloy is continuously cast in a bath of water to produce 6-metre long bars with a diameter
of 500 mm. The same bars are extruded to produce a diameter of 300 mm. The extrusion process enhances the mechanical and structural characteristics
of the metal as its fibres are further compacted. The extruded bars are then cut into discs, heated to a temperature of 300° C and machined on a
hydraulic press, with a gradual pressure of 3,000 tons. A second press press-forges the semi-finished product (known in jargon as the "formaggella")
with a pressure of 8,000 t, applied in 30 seconds. The piece obtained in this way, though still unfinished, presents a strong structural tension caused
by the extrusion and forging, which have forcefully moved the fibres. Structural tension is synonymous with fragility so the piece undergoes T6 heat treatment,
which relaxes the internal forces and restores the mechanical features of the alloy.
At this stage comes machining: numerically-controlled vertical turning to machine the rim and centre and spigot milling for constructing the spokes.
Flash removal from the edges is carried out by hand, while surface compaction is achieved by "grit blasting" with 0.1 mm steel grit. Final anodization gives it its
colour, without increasing the weight.Every operation is rigorously checked by Quality Control, which involves all production departments, and is carried out on
all wheels destined for racing as well as those fitted on street vehicles. |
• The absence of moulds: the semi-finished products are the same for all types of wheels, while the final shape of the wheel is determined by numerically-controlled mechanical machining, which is much more flexible than presses. |
• Mechanical features being equal, a forged wheel is much lighter in weight than a cast wheel. |
• The mechanical and physical features of a forged wheel are equally distributed over all the points of the piece; while a cast wheel presents features which vary between the centre and the perimeter. |
• A forged, more lightweight wheel has a lower angular moment, therefore lower inertia. This leads to a lower absorption of power in the acceleration stage, and greater effectiveness during braking. |
• The light weight of the wheels increases the suspended mass/non-suspended mass ratio, which means better functioning of the suspension. |
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