The AEZ Production Story – Part II
For the idea to become reality, prior to the serial production of alloy rims a basic mold is required – the permanent mold. Making the original form of the rim is one of the most critical processes on the way from the idea to the serial rim. Precision and top quality are decisive for the subsequent steps, with the tolerances being in the micron realm.
When all computer simulations are completed and possible adaptations carried out, the project is handed over and the production process initiated by forwarding the technical specifications to the permanent mold maker. In the production of AEZ alloy rims the so-called permanent mold casting process is used for one-piece wheels. In a one-piece wheel the rim star and rim well are made from one piece. The one-piece wheel is the most widely used type of alloy rim.
Construction of a permanent mold
Permanent molds are reusable molds used for casting (permanent mold casting) of metals and alloys. This metal permanent mold is usually made from special steel and consists of several, partially movable parts so that it can be opened after pouring and solidification as well as closed to be ready for the next casting. The making of a permanent mold takes roughly 3 to 4 weeks. A permanent mold can be used 50,000-80,0000 times for one wheel design.
First sample casts
AEZ uses low-pressure die casting permanent molds for its rims. This casting process has proven particularly suitable for casting rotationally symmetric parts, as rims are called technically. Roughly 90 percent of all alloy rims are manufactured using this process.
The permanent mold is examined in detail at the AEZ rim production site, which is followed by the casting of the first sample wheels. These sample wheels are then sent to the TÜV, an EU-wide inspection and certification authority that carries out all relevant safety tests. At the same time, the AEZ development division inspects the sample wheels for variations and damage.
For a better understanding – the radial fatigue test:
The radial fatigue test is about applying eccentric load to a wheel.
- Short run (75% of the load, 200,000 cycles): tests the construction
- Long run (50% of the load, 1,800,000 cycles): tests the material
One factor decides whether a test is positive: the wheel must not crack.
Additional tests include the impact test and the rolling test. Furthermore, after the completion of the casting process every wheel is tested for material density in an X-Ray apparatus. If irregularities occur during this process the respective wheel is instantly removed from the production process and melted down.
Once the sample wheels have passed all tests and the TÜV certificate is obtained, the ALCAR Leichtmetallräder GmbH technical division gives the final clearance for serial production, and then nothing should stand in the way of daily rim use.
Preview: In the next episode, you will hear more about serial production and the finishing touches to a rim.