Saint Jean Wheels has developed patented hybrid technology to optimize the weight of aluminum rims without compromising on robustness versus design.
Saint Jean Wheels set out to test the boundaries of weight reduction for an aluminum rim without compromising the design that gives it its character. This process of reflection led to the COBAWHEELS™ technology, which combines the cutting-edge manufacturing processes used in aeronautics and the automobile industry: flow-forming, the COBAPRESS™ and friction stir welding.
The advantages of COBAWHEELS™ technology:
- A rim well manufactured using flow-forming can achieve low thicknesses with extrusion alloys that have high mechanical properties.
- The front face made in COBAPRESS™ has a flexible design while also delivering advanced properties that promote the rim’s fatigue resistance.
- Assembly of the two parts using the cold friction stir welding process enables perfect cohesion of the materials used.
From the French for “COuler (Pouring) > BAsculer (Tilting) > PRESSer (Pressing)”
This patented technology is tried and tested in the manufacture of automobile safety parts. It is perfectly suited to weight-reduction, mechanical strength and flexibility of design requirements for aluminum rims.
Description of the COBAPRESS™: this hybrid process consists of casting a preform and hitting it one time with a forging press.
Advantages over casting:
- Improves material quality and properties : E155 ASTM < 1
- Eliminates internal defects and optimizes mechanical properties
- Reduces weight thanks to improved mechanical properties
- Excellent fatigue resistance thanks to the skin effect of the COBAPRESS™ technology
- Enables radiography and penetrant sample inspection
Compared with forging:
- Material is more economical and recyclable in the process
- Production of complex shapes thanks to greater freedom of design
The characterization of the COBAPRESS™ process has been the subject of several scientific publications. The summary below provides a better understanding of the transformations produced during the manufacturing cycle and the subsequent results.
This process, commonly used in the manufacture of cast aluminum rims, is applied by Saint Jean Wheels cold to a preformed extruded tube to reduce the weight of the rim well.
The advantages of cold flow-forming:
- Reduces thicknesses.
- Improves mechanical properties.
- Applicable for small or large production runs.
Friction stir welding
This innovative process is used in the assembly of components that do not contain filler metal or go through a liquid phase, thereby preserving the metallurgic quality of the welded area of components.
Saint Jean Wheels is the first to use this process for wheels.
The advantages of FSW for wheels:
- No filler metal required.
- Different materials can be assembled and their mechanical properties preserved.
- Minimizes thermomechanical stresses and deformations.
- Suitable for small and large production runs.