Brake calipers are essential to the car’s ability to stop and are one of the most important automobile parts. In a disc-braking system the car wheels are attached to metal discs that spin along them. Brake calipers squeeze the brake pads against the surface of the disc, which is made of cast iron in most commercial vehicles but can be of Carbon Composites in racing cars and motorbikes. The squeezing action creates a friction, sufficient to slow or stop the vehicle, producing instantly a lot of heat, that must be dissipated quickly to avoid problems to the whole braking system.
Brembo offers an impressive catalogue of disc brakes for cars, motorcycles, commercial vehicles and racing. The Italian brake firm’s research and development division constantly looks for new records to beat, developing stronger, lighter and safer braking systems. The development of a brake caliper made of secondary aluminium alloy, featuring a mechanical strength similar to that obtained with a primary alloy and very high homogeneous microstructure, combined with a production cycle time achieved with the die-casting method, is the final target of a EU-Life CRAL (CRadle-to-grave Approach to Light alloys) project, which was started by Brembo in 2016.
Cannon Ergos S.p.A, whose experience in vertical aluminium die-casting equipment dates back more than 50 years, shared the execution of this 36-month project.
An innovative approach characterised this challenging task: the use of semi-solid aluminium alloy injected with laminar flow and a very high specific pressure, using vertical injection technology. The liquid alloy is stirred directly into the machine under strictly controlled conditions, keeping it highly viscous, and immediately transferred in a closed mould using a hydraulic piston with a bottom-up injection path.
A special 10,000 kN Cannon Ergos vertical die-casting press has been built and installed in Brembo’s premises for this development.
The most innovative aspect characterising this new equipment is how the alloy is dosed, prepared and directly injected in one of the injection sleeves of the machine.
A special design characterises this press: a short-stroke design and a multiple container (a multi-injection sleeve) that allow to reduce the cycle time, thanks to the possibility to perform different operations in hidden time.
Advantages of this project include:
- Faster-cooling brake calipers, lighter than the previous ones, providing superior mechanical characteristics with a lower weight impact on the car or motorbike wheel, and the lower environmental properties impact are the improvements desired with this project for the final product.
- Shape and geometry of the caliper not obtainable with the traditional moulding technology.
- Faster cycle time, reduced investment in casting equipment, a near-to-shape caliper, ready to be used with limited post-processing operations, are the industrial production and economic returns.