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The required properties are: lightness (it is a non-suspended mass), stiffness (any deformation compromises the kinetics of the suspension and braking) and reliability, (as one of the safety components).
The uprights were usually manufactured through a long and complicated process of forming and cutting steel sheets, which included welding, heat treatment, CNC machining and finally painting to protect against corrosion. This process can’t optimize the mechanical performances of the piece, making the uprights heavier than they should have been. Moreover, being a welded piece, it presents a structural anisotropy that shortens its lifespan, and therefore its reliability and life expectancy.
In 1998 CRP began to work alongside the Minardi F1 team, supplying them the engineering process, the manufacturing process optimization and the manufacturing of front and rear uprights: they began from the study of the Rapid Casting process.
Rapid Casting is based on the combination of Rapid Prototyping technology, to manufacture the disposable pattern, and Investment Casting technology (lost wax casting) with Titanium alloys.
The RP pattern is made using the Selective Laser Sintering technology (SLS), allowing complete shape conception freedom: thus reducing undercut and tool path problems during CNC machining.
CastForm® is the material used for Rapid Casting patterns: developed from the cooperation between DTM Corp. and CRP in 1996, it was developed for creating lost patterns in particular for highly reactive materials such as titanium.
The production of ash during the evacuation of the ceramic shell has been reduced: the ash, when in contact with the titanium, would produce chemical reactions that would damage the casting, and have therefore to be eliminated before pouring the cast metal in the ceramic shell.
It’s therefore possible to create the product along its mechanical stress axes, and to obtain a perfect reproduction of all details of the RP pattern, with tolerances and surface finishing like fully machined parts, thus allowing you to think about what you need and not how to machine it.
The Rapid Casting procedure is composed of a number of steps:
- A disposable pattern in Castform is made by RP;
- The pattern undergoes wax infiltrations (immersion and capillarity) to increase its strength (to avoid handling breaks);
- The pattern is immersed in a ceramic bath;
- Slurries, stuccoing and exsiccation;
- The lost pattern is evacuated;
- Dewaxing with flash firing or in an autoclave for drying of the ceramic shell
- Alloy casting with inductor or voltaic arc;
- Pouring, cooling, reduction of the shell, shot peening, gate cutting, heat treatments.
The casting structure is formed of an aggregate of grains or polyhedral crystallites which produce isotropy compensation, while in a solid metal they are anisotropic: it is obvious that isotropy has great advantages, for instance, FEM calculations are very close to the real behaviour thanks to the isotropy of the piece.
Rapid Casting technology was immediately highly appreciated by customers because it provided significant advantages.
For example the possibility of maximum post-stress control of the components compared to carbon laminated parts, durability and reliability (a casting is naturally isotropic for compensation), fewer design and shape limitations and the possibility to reduce weight (adding pockets) and increase stiffness of (adding ribs) the part during the racing season.
CRP therefore began, in strict collaboration with its Extra-F1 customers, to study a new kind of upright obtained with this same technology used in F1: the Rapid Casting of 17-4PH steel alloy, with lost pattern made by RP-SLS.
The final product is supplied fully CNC machined and complete of treatments with inspection certificates (material, RX, FPI, HT, etc…), according to the ISO9001:2000 certification.
The winning point of this new technology is the possibility to deliver a “turnkey” solution and thus ready to race, where CRP is involved and collaborates with the customer from the beginning, strongly contributing in terms of engineering and co-design.
Everything is about the optimisation of the 3D design, in order to maximise the whole potential and the advantages coming from the “CRP method”.
From a technical point of view, the CRP uprights do have higher mechanical performances and an improved reliability, with further weight saving, which is a fundamental property for the non suspended masses of a vehicle.
Since 2002, CRP has co-operated in these series: ALMS, WRC, MotoGP and Rally Raid.
In WRC and Rally Raid, CRP strongly co-operated from the first design stage, in order to optimize the part project together with the constructors’ technical staff, and this alliance was finally rewarded.
In 2002 Peugeot and MARCUS GRONHOLM won the World Rally Championship while the Mitsubishi Team won the Paris-Dakar twice, in 2005 and in 2006.
Both the teams had the uprights studied and manufactured in collaboration with CRP Technology.
The adventure is continuing ... Other collaborations have lead and keep on leading to other World Championships for CRP and its partners.
