THE MANUFACTURING PROCESS FOR ORIGINAL BMW LIGHT ALLOY WHEELS.
Original BMW Light Alloy Wheels have to meet special requirements — and not just from a design perspective.
To meet these criteria, BMW has every wheel produced using optimal production methods and the latest manufacturing technologies. Just how much expertise and technology goes into manufacturing Original BMW Light Alloy Wheels? Take a look.
KEY DEVELOPMENT CRITERIA:
- High durability
- X-Ray testing
- High level of thermal conductivity
- Reduced weight
- Optimum ventilation of the brake system
STEP 1: DESIGN. FROM CONCEPT TO CLAY MODEL.
A light alloy wheel is a key factor in defining the appearance of a vehicle. For that reason, a detailed design process is essential to ensure the wheel styling is a seamless match to the vehicle:
- The fundamental properties of the rim are defined. Various criteria are addressed, from maximum efficiency to dynamic driving properties.
- Sketches are made for each model, perfectly matching the design of the vehicle.
- The best designs are turned into virtual CAD models and assessed on the relevant BMW model.
- Clay models are created on a 1:1 scale, making it possible to effectively judge position and effect.
- A conclusive assessment determines how well the wheel styling complements the vehicle model, resulting in final approval.
STEP 2: PRODUCTION TECHNOLOGY.
SELECTING THE IDEAL MANUFACTURING METHOD.
Various technologies are used to manufacture Original BMW Light Alloy Wheels. Light alloy wheels can be manufactured from either cast or forged aluminum. A forged aluminum wheel is much lighter than its cast counterpart due to greater rigidity. The reduced weight makes for less un-sprung mass, and together with the suspension, evens out bumps in the road and improves driving and brake response. For this reason, the more performance-oriented light alloy wheels are generally manufactured using the forging method.
The entire wheel, including the styling area, is cast in liquid aluminum.
- Simple production
- Low costs
- Suitable for large
and small volumes
- Greater weight
The wheel is forged from a solid piece of aluminum. The styling area may also be milled.
- Extensive design freedom
- Greater rigidity
- Lower weight
- Higher degree of gloss
- Higher cost per wheel
- Lengthier processing time (milling)
STEP 3: METHODS FOR REDUCING WEIGHT.
Cutting-edge production techniques are used to further improve the properties and the design of a cast or forged aluminum wheel. These methods ensure a high degree of rigidity combined with a very low weight, which has a positive impact on driving properties and fuel consumption.
FLOWFORMING. FOR OPTIMUM DENSITY.
This method is used exclusively for forged wheels and optionally for cast wheels to create a thinner rim base wall.
- Weight: Compared to a regular cast wheel, it is possible to achieve a weight reduction of approximately 2.2 lbs. (1 kg) in an 18-inch wheel.
- Material properties: The rim base processing used in flowforming also improves material properties and density.
UNDERCUT. FOR DIMENSIONAL SPOKES.
This method can be used for both forged and cast wheels. Since material is removed from the spokes via milling, non-strength related mass is reduced.
- Weight: As compared to a forged wheel, it is possible to reduce weight and create a high-quality visual appearance.
- Material properties: An undercut between the spoke connection and the well base gives the rim styling a dimensional appearance.
STEP 4: SURFACE DESIGN. INNOVATIVE & STYLISH.
Regardless of which production technologies are used, the surfaces of Original BMW Light Alloy Wheels can be finished in a variety of ways. The basic feature—powder coating—gives the wheel strong resistance to environmental factors such as corrosive road salt.
In the past, light alloy wheels were often painted silver with a clear lacquer finish. Today, the BMW portfolio includes numerous designs and refinements that require an elaborate finishing process. Not only do customers benefit from a diverse range of styling options, they also benefit from a constant increase in the quality of coatings.
STEP 5: TEST CRITERIA. TAKING A CLOSER LOOK.
The quality of Original BMW Light Alloy Wheels takes priority throughout the entire development process. All products must meet the most rigorous design and testing procedures before being labeled as Original BMW Light Alloy Wheels.
Laboratory test procedures are designed to simulate all types of exposure and ensure maximum suitability for everyday use. Specific tests (radial run-out test and salt water spray test) are also conducted to help assess the potential for damage from curbside contact, potholes or durability in all weather conditions.
Stability and fatigue strength for safety under extreme strain.
Entrapments and gas bubbles should be minimized. X-ray test is applied to all cast wheels to examine the microstructure of the material. (It is not required for forged wheels, which are made from a prefabricated fine-grain aluminum alloy.
Durability in spite of seasonal environmental impact.
In the salt water spray test, light alloy wheels are exposed to an aggressive salt water spray mist for hours on end to test the corrosion resilience of the finish.
This test simulates practical use over a period of several years on heavily salted roads. Original BMW Light Alloy Wheels are required to pass it.
Unsurpassed performance under extreme loads.
For extreme driving conditions, the wheel disc is tested for rotational bending strength. A special test bench simulates loads applied when taking bends at maximum speeds.
These tests measure how Original BMW Light Alloy Wheels withstand extreme maneuvers.
THE HIGHEST OF STANDARDS
BMW requirements exceed general standards such as those applied by TÜV for the aftermarket.
- The number and duration of test scenarios far exceed statutory requirements.
- Original BMW Light Alloy Wheels are tested and checked dynamically, statically and in simulations under extreme conditions – well above everyday exposure. For example, racetrack exposure — equivalent to a customer traveling 186 mph — is simulated on a test bench. A rotation bending test involves more than a million load changes.
- BMW only markets wheels and tires that have demonstrated their quality by passing all tests. Random quality tests and controls are conducted throughout the entire production period.
- Since there are such a large number of manufacturers, there are considerable differences in how product testing is conducted.
Stability and fatigue strength for safety under extreme strain.
To detect even the smallest leaks, this test exposes Original BMW Light Alloy Wheels to extreme heat and cold as well as increased tire pressure.
The leak test ensures that no air escapes — even in extreme conditions.
Powerful performance in spite of curbs, cornering, high speeds, acceleration and brake forces.
Not only are new BMW models such as the BMW M4 tested under extreme stress on the Nürburgring track; the load data is determined for a range of different wheel and tire test benches, as well.
Original BMW Light Alloy Wheels are required to undergo an uncompromising endurance test on this race track profile.
For greater longevity.
Wheels are subjected to rigorous testing to simulate durability during day-to-day usage. The biaxial test bench, commonly referred to as ZWARP, is used to carry out service load tests. During a test, the wheel and tire run on or inside a drum and are exposed to contact and lateral forces simulating a ride on the Nürburgring — partially at speeds of more than 155mph.
Original BMW Light Alloy Wheels are not approved for sale until they pass the service life test on the ZWARP.
- Reduced wheel weight
- Forged Original BMW Light Alloy Wheels are usually lighter than comparable cast wheels
- Long-term corrosion resistance due to high-quality surface treatment
- Suitability for winter use
- Excellent handling and ride comfort
- Maximum brake clearance
- Designed to match BMW sport suspension
- Large selection of individual styling options
- Combination of polished, blasted and forged surface areas
- Highly exclusive, top-quality appearance