First: where does TURBU fit among wheel manufacturing technologies?

Before looking at the details, it helps to place TURBU within the manufacturing processes already familiar to the wheel industry.

Why change the way an alloy wheel is cast?

Conventional low-pressure casting is a mature and highly effective manufacturing process. It is capable of producing high-quality aluminium wheels in very large volumes.

But every casting process imposes manufacturing constraints on the designer.

According to the TURBU development documentation, conventional low-pressure wheel casting typically reaches a practical minimum cast wall thickness of around 6 mm. Below this range, the aluminium can begin to solidify before the mould cavity is filled reliably.

This means that a wheel designer cannot simply define the exact final geometry and expect it to be cast directly.

A manufacturable casting blank must first be produced. Material can then be removed by machining, and the conventional manufacturing route can also include T6 heat treatment to achieve the required material properties.

The potential advantage is therefore not simply that less material remains in the final wheel. The process attempts to avoid putting some of that excess aluminium into the casting in the first place.

Modern wheels face a difficult engineering contradiction

The development project also highlights a broader problem facing modern wheel engineering.

Vehicle manufacturers want to reduce mass, yet wheels on large SUVs, performance vehicles and electric vehicles may simultaneously need to carry higher loads.

The TURBU project documentation gives the example of an 18-inch aluminium wheel that historically might have weighed around 12 kg and been designed for a load of approximately 690 kg. For modern heavy vehicles, required wheel loads can exceed 800 kg and in some applications approach 1,000 kg.

If the manufacturing technology and basic design approach remain unchanged, increasing the required load capacity can mean adding material.

Vehicle manufacturers need lower mass, while the wheel itself may be required to carry more load.

Flow Forming is already one established answer to this problem. TURBU approaches it from another direction: optimisation begins before the wheel leaves the mould.

How does TURBU work?

The core idea is not simply to inject molten aluminium into a mould at higher pressure.

Fast filling alone can be problematic. Uncontrolled melt flow can entrain gases and oxide films, contributing to porosity and other casting defects. In a safety-critical component exposed to cyclic loading, the quality of the casting structure matters greatly.

TURBU therefore combines several elements:

• rapid pressure-assisted mould filling,
• controlled, low-turbulence melt flow,
• vacuum assistance,
• carefully controlled melt and mould temperatures,
• rapid solidification and cooling,
• and extensive process monitoring.

The resulting material properties depend not only on pressure but also on alloy chemistry, melt quality, temperature, timing and cooling conditions.

The alloy is part of the process

The development programme investigated different alloy compositions and processing conditions.

One material identified as particularly suitable was AlSi10MnMg, commercially available in variants such as Rheinfelden's Silafont-36.

For an automotive wheel, however, maximum tensile strength alone is not enough. A wheel experiences repeated bending, radial loading and impacts throughout its service life. Strength therefore has to be considered together with ductility and fatigue behaviour.

One result from the development work illustrates how sensitive the relationship can be.

With one investigated composition of approximately 10.5% silicon and 0.35% magnesium, the wheel did not pass the required rotating bending test. After the composition was changed to approximately 9.5% silicon and 0.25% magnesium, the test was passed.

The lesson is important: TURBU is not merely a machine or casting technique. Alloy composition and process control form one engineering system.

Why can the TURBU wheel be lighter?

The difference between 25.7 kg and 23.5 kg immediately after casting is only part of the story.

The more important difference appears further along the production chain.

A near-net-shape casting can reduce the amount of aluminium that must first be cast only to be removed again during machining.

Entec-Stracon states that the process has the potential to reduce aluminium consumption by up to 40%, machining time by up to 80%, and energy consumption by approximately 50%.

These figures should be understood as reported process potential rather than guaranteed values for every wheel geometry or production line.

Another major difference is that the investigated TURBU production route does not rely on the conventional downstream T6 heat-treatment stage used in traditional low-pressure-cast wheel production.

The required properties must instead emerge from the correct alloy, casting conditions, solidification and cooling process.

The trade-off: TURBU has a narrow process window

Removing manufacturing steps does not make the process inherently simpler.

T6 heat treatment in a conventional production route can help develop and homogenise material properties after casting. TURBU omits this stage, placing greater demands on the quality and repeatability of the casting itself.

The final development report explicitly describes a very narrow process window.

During one production cycle, the system can generate approximately 20,000 measured values while working with around 220 adjustable parameters. A human operator cannot continuously evaluate and correct this volume of process information during a cycle lasting only a few minutes.

This is where automated process control and artificial intelligence become relevant.

But is a lighter TURBU wheel safe?

For an automotive wheel, a strong material specimen is not enough.

What ultimately matters is the behaviour of the complete wheel.

During the development programme, complete wheels were cast in different configurations, machined, coated and subjected to wheel-level testing. Material samples were also taken from finished components to investigate strength and ductility.

This distinction is fundamental.

A new alloy may show impressive mechanical properties in a laboratory specimen, but a real wheel combines: material + geometry + manufacturing process + local stress distribution + complete-wheel performance.

This is also why comparing manufacturing technologies and comparing wheel safety standards are two different questions.

TURBU vs Flow Forming? That may be the wrong question

At first glance, TURBU could appear to be a competitor to Flow Forming.

Flow Forming is already used to reduce wheel mass and improve material properties, particularly in the rim section. After casting, rollers mechanically form the rim of the wheel blank.

If TURBU can reduce weight during casting itself, it might therefore seem that Flow Forming becomes unnecessary.

The development programme demonstrated the opposite.

TURBU and Flow Forming can be combined.

The percentage savings cannot simply be added together. Flow Forming primarily affects the rim region and the final result depends on the individual wheel design.

But the engineering principle is clear: the new casting process and subsequent mechanical forming are not mutually exclusive.

Could TURBU give wheel designers more freedom?

Reducing minimum cast-section thickness does more than reduce weight. It changes the geometries that can potentially be manufactured.

With conventional casting, a fine or thin feature may be difficult not because it is structurally undesirable, but because molten aluminium cannot reliably fill and solidify in that geometry.

The TURBU development programme worked with real wheel geometries during different stages of the project, including designs associated with BORBET, CMS and BBS.

The documentation describes a CMS geometry that, according to the project team, could not be produced in the required form using the conventional low-pressure process used for comparison. Later development work also used a BBS wheel geometry, including experiments involving Flow Forming.

The potential advantage is therefore not merely to “remove aluminium”. The designer may gain more freedom to place material where the wheel structurally needs it instead of where the casting process requires it.

Why is recycled aluminium important to TURBU?

Another part of the development programme investigated whether a safety-critical wheel could be produced with a much higher proportion of recycled aluminium.

TURBU wheels were produced during the project using up to 100% recycled material. According to the final report, properly controlled chemistry and process conditions did not reveal a fundamental reason preventing such material from being used.

But “100% recycled aluminium” does not mean arbitrary scrap aluminium.

The reports devote considerable attention to:

• alloy chemistry,
• trace elements,
• oxidation,
• melt cleanliness,
• and precise process conditions.

Less waste before machining even begins

Near-net-shape casting can also change the character of manufacturing waste.

Conventional machining creates aluminium chips with a large surface area that can be contaminated by cutting fluids. Recycling this material is more complicated than simply remelting a clean solid piece of aluminium.

When less machining is required, a greater proportion of returned material can instead consist of relatively compact casting-system material such as runners and overflow sections.

The sustainability argument is therefore broader than final wheel mass. It concerns how much primary material enters the process, how much must later be machined away, what form the production scrap takes and how much energy the entire manufacturing route requires.

Is TURBU better than a forged wheel?

Current evidence does not support that conclusion.

The technologies work differently.

A forged wheel begins with an aluminium billet that is plastically formed under high pressure and then extensively machined into its final geometry. Forging can achieve excellent mechanical properties and low mass, but it is also a more demanding and generally more expensive manufacturing route.

TURBU remains a casting technology. Its objective is to improve the relationship between weight, material properties, manufacturing time and material consumption within a process suitable for industrial production.

The development reports currently available compare TURBU primarily with conventional low-pressure casting. They do not provide a controlled comparison of the same wheel design manufactured once by TURBU and once by forging.

From research project to a production BMW wheel

TURBU did not suddenly appear in 2026.

Entec-Stracon began developing turbulence-reduced pressure casting in 2017. Feasibility studies, patent applications, hundreds of experimental castings and several development projects followed.

A later development stage involved machine manufacturer Oskar Frech and a dedicated pressure-casting cell. The central question gradually changed from:

“Can a wheel be produced this way?”

to:

“Can the process be controlled reliably enough for industrial series production?”

In 2026, an important piece of evidence arrived.

BMW announced new 20- and 21-inch M Performance 1075 M wheels for the BMW M5 using a High Pressure Casting process developed by Entec-Stracon.

BMW describes the production technology as High Pressure Casting (HPC). According to BMW, the mould is filled under high pressure and vacuum in approximately 0.05 seconds, while around 80 sensors and an AI-supported system monitor the production process.

BMW states that the process can approximately halve energy consumption and reduce wheel weight by up to 20% while maintaining the required properties.

TURBU, conventional casting, Flow Forming and forging: the practical comparison