The manufacturing processes of alloy wheels and carbon fiber wheels are completely different.
Let's talk about alloy wheels first
Forged wheels are different from cast wheels. Theoretically, the strength of both sides is a problem.
Aluminum alloy A356 with casting wheel hub (aluminum) tensile strength of about 230MPa
The tensile strength of forged wheel hub (aluminum) reaches 330-350 MPa；; The strength is 30% higher than that of the cast wheel hub, so the weight can be made lighter and thinner. Aluminum 606 1
Simply put, casting is a product made by melting aluminum alloy, pouring it into a mold and letting it naturally cool and solidify. In this process, aluminum alloy will produce porosity, looseness and slag inclusion. Not only the tensile strength, but also many casting defects.
Forging wheel hub directly presses aluminum alloy into the mold with a press of more than 10,000 tons, and the density will be higher. After forging, the strength, grain size and compactness of the alloy will be improved.
Aluminum alloy material used for forging wheel hub is different from casting alloy, because casting alloy needs some amorphous components, and its thermal conductivity is not as good as forging wheel hub; Forged wheels are denser, lighter and thinner, and have better safety. For casting wheels, the alloy should have good fluidity and flow into the mold, so some non-alloy materials, such as silicon, should be added; Forging does not need to consider fluidity, so the influence is more obvious. The surface of cast wheel hub may be deformed and cracked by impact tester, but it will not be forged, and it will rebound and deform and crack after washing.
The existing forging technologies are also divided into three categories:
Forging with a hydraulic press of more than 10,000 tons (the greater the pressure, the higher the alloy density and strength).
Casting spinning
Pressurization in casting process
Theoretically, the strength of forged wheel hub is 30% higher than that of cast wheel hub. Even if the weight of the former is reduced by 20%, the strength is still stronger than that of cast wheel hub. This is especially true for carbon fiber wheels, which are lighter in weight and higher in strength.
Higher strength means that everything can be made lighter, and cars pursue lightweight. The unsprung weight loss 1 kg is equivalent to 65,438+00 kg on the spring. Lightweight also makes the car more maneuverable (lighter wheels, faster acceleration, shorter braking distance and safer).
Lightweight of vehicle and wheel hub is the easiest, because the lightweight change of body structure involves many parts, and the wheel hub can be used directly as long as the strength requirements pass, without considering other parts.
Casting/forging wheel hub has swallowed up the wheel rim market now, so has carbon fiber wheel hub, because good things will definitely replace bad ones, first the high-end market, then the technology will be broken, and then the cost will come down and enter the low-end market.
At present, battery, one of the most critical technologies of new energy vehicles, has not made a major technological breakthrough. Considering that the design weight of long-life battery is relatively heavy, the wheel hub is 1KG, and a five-wheeled car (plus a spare tire) is five kilograms lighter, so the battery can be made bigger and its battery life will be longer.
There are two processing methods for carbon fiber wheels.
Vacuum hot pressing, RTM process
The first one is generally used now, but only a few companies can do it, Koenigsegg.
The carbon revolution adopted RTM process.
The other is Lamborghini's patent, forging carbon fiber, but it has not been used to make wheels so far. Maybe forged carbon is not as strong as layered design.