The automotive industry is facing a major challenge: the Euro 7 standard stipulates strict limits for particulate matter emissions. Cars will then only be allowed to emit around three milligrams of particulate matter per kilometer – a drastic reduction compared to today’s values of up to 40 milligrams. To achieve these ambitious targets, car manufacturers are increasingly relying on innovative technologies such as coated brake discs.
Laser cladding is a promising process for manufacturing these ultra-modern brake discs. In this application, a special material powder made of stainless steel and hard carbide is welded onto the surface of the brake disc using a laser. The result is brake systems that not only drastically reduce particulate emissions, but also minimize wear and prevent corrosion.
However, the design and development of this new coating technology also creates new challenges in post-processing. With the VLC 450 DG grinding machine, EMAG offers a specialized solution for the machining of these high-tech brake discs.
We spoke with Jannik Röttger, Head of Grinding Technology at EMAG, about this innovative technology and EMAG’s response to the challenges of the Euro 7 standard.
Jannik, the Euro 7 standard poses new challenges for the automotive industry. How is EMAG responding to this?
Jannik Röttger, Head of Grinding Technology at EMAG
In order to achieve the goals of the Euro 7 standard, car manufacturers are increasingly relying on coated brake discs, which are ground in the final processing step. In the grinding machine, hard-coated brake discs do exactly what they are supposed to do in low-emission vehicles – build up a high braking effect without any loss of material. In the grinding process, however, we want to achieve exactly the opposite. The aim is to remove material in the shortest possible time in order to achieve the required geometry and surface properties.
Our answer to this is the VLC 450 DG, a double-sided surface grinding machine that has been specially developed for the machining of these hard coatings of brake discs. It is the result of our decades of experience in the design and manufacture of vertical grinding machines, adapted to the new requirements of the hard coating of brake discs.
EMAG VLC 450 DG: High-precision grinding machine for brake discs. . The innovative design enables precision grinding and optimum removal of grinding particles, making it the ideal solution for the machining of modern, coated brake discs.
You mentioned the laser cladding process. Can you tell us more about this coating process?
Laser cladding is a build-up welding process that we use at EMAG to coat brake discs. A special material powder is fed into a laser tool via a channel. The laser melts this powder and at the same time fuses it to the surface of the brake disc.
Depending on the requirements, we can apply one or two-layer systems. In a two-layer system, we first apply an adhesion promoter layer and then the actual wear protection layer on top. Some designers and developers also rely on one-coat solutions.
The special thing about our approach is that we consider and optimize both the coating process and the subsequent sanding process holistically. We set the coating parameters in such a way that the surface produced results in the shortest possible grinding cycle times and low grinding wheel wear. This is crucial for cost-effective production.
Euro 7-compliant brake disc: coated and precision-ground. The smooth and even surface shows the precision of the grinding process, which is crucial for meeting the Euro 7 standard.
What makes the VLC 450 DG so special for this application?
The VLC 450 DG is characterized by several factors. Firstly, we use double-sided face-grinding, which produces precision cross-grinding structures. These improve the tribological running-in behavior of the brake discs. The large-area contact between the grinding wheels and the brake disc ensures optimum component support and, thus, high component quality of the brake discs, which are very unstable in the axial direction.
VLC 450 DG: Innovative parallel spindle technology for precision double-sided face-grinding. This arrangement enables high-precision and efficient grinding of hard coatings of brake discs to meet the Euro 7 standard.
An important point is the vertical design of the machine. It ensures optimum removal of the abrasive hard material particles, which increases the service life of the machine components. This design also facilitates accessibility for set-up and maintenance work.
In addition, we have integrated a special cooling concept that ensures good thermal stability. The machine base made of mineralite minimizes vibrations and thus ensures maximum precision. Last but not least, we have integrated a machine shuttle outside the work area, which forms an ideal interface to further automation.
VLC 450 DG: Service-friendly design for optimum accessibility. The generously dimensioned service doors provide unhindered access to the work area. The well thought-out design underlines the efficiency of the machine not only during operation, but also when servicing is required.
How do you deal with the different requirements of the various coating systems?
This is indeed a challenge. Single and double-layer systems require different grinding strategies. With single-layer systems, we can work at higher cutting speeds, while double-layer systems tend to require lower motor speeds with high torque.
To make it a little clearer: The monolayers are similar to hardened steel in terms of their machining behavior, while the wear layers of the two-layer systems are more like carbide. The spindle drives of our machine are flexible enough to optimally machine both variants. We adapt the motor characteristics and grinding parameters individually to the respective coating system.
Multi-layer brake disc before and after double-sided face-grinding. Left: the rough, unmachined surface after coating. Right: the result after double-sided face-grinding with the EMAG VLC 450 DG.
What role did productivity play in the design and development of the VLC 450 DG?
Productivity is our top priority, because we know that our customers need maximum efficiency in batch production. This is why, for example, we have developed a tool concept that enables changeover times of just a few minutes. The grinding tool is designed as an interchangeable ring and weighs less than five kilograms, which allows for quick replacement.
The integrated machine shuttle is also designed for seamless integration into automation lines. Thanks to the optimized coordination of the coating and sanding process, we also achieve short sanding cycle times with low sanding wheel wear.
Grinding tool change ring of the VLC 450 DG: Efficiency in seconds.
How important is the collaboration of different experts in the development of such solutions?
This is crucial. At EMAG, turning, grinding, coating and laser experts work closely together to develop a perfect overall solution. This is the only way we can ensure that the coating has optimum properties in the braking system and is easy to machine at the same time.
This holistic understanding is our great advantage and enables us to develop customized solutions for our customers – whether for the overall process or specifically for the grinding process. We can configure and validate the entire laser process if the customer so wishes, but we also always keep an eye on the subsequent sanding process.
In conclusion: How do you see the future of brake disc production?
I am convinced that coated brake discs are the way of the future. They enable us to comply with the strict emission regulations and at the same time improve the service life and performance of the brakes.
With solutions such as the VLC 450 DG, we are ideally positioned to support our customers in this change and to make the production of coated brake discs efficient and of high quality. We tested the machine for three years in prototype construction and continuously optimized it. It has already successfully machined a thoudands of brake discs with a wide variety of geometries and coating systems. This gives us and our customers the certainty that we are equipped for the challenges of the future.
Jannik, thank you very much for the interesting insights!
Thank you very much for the interview!
You can find all further information about the VLC 450 DG brake disc grinding machine here.
