Production in the Magic Triangle
Drivers expect that their cars’ engines and fuel-injection systems will last for 250,000 kilometers or 15 years — performance achieved thanks to Bosch engineers’ expertise. Faced with the ever-increasing demands on components, the engineers respond with a holistic approach encompassing materials technology, component design and production engineering.
Vehicle components are becoming smaller and smaller. But the demands being placed on them continue to grow. As a result, the stress on them is rising as well. A “brilliant” design trick no longer gets to the root of the problem. Instead, materials science, production engineering and design must all work closely together. This “magic triangle” turns product development and manufacturing into an extremely complicated process: After all, a wide variety of promising materials, a pallet of suitable production processes and, of course, a vast number of design ideas are often available. But two hurdles still have to be cleared: The component must perform its function reliably and it must be possible to produce it cost-effectively.
For example, diesel direct injection common rail systems working with pressures of 1,600 bars are already on the market. In the coming years, systems working with 1,800 bars are being planned. And developers have their eye fixed on even higher pressures in their drive to make an engine’s operation cleaner and more economical. But the loading capacity of steel is reaching its limits. The highest strains occur in high-pressure bores and, in particular, in areas where two bores meet – at a so-called bore overlap. Here, there is a real danger that the material could tear. The component becomes defective. Bosch researchers are optimizing all parameters to prevent that from happening. First, the material:
An optimum degree of purity is necessary. Non-metallic inclusions such as oxides and sulfides found in all steel have to be drastically reduced because they lead to component failure. Second, the design: The angle at which the bores meet determines the stresses in the material. With the help of simulation, the angle can be selected in a way that minimizes the stress concentrations. Third, production: Even the slightest burr left behind by a drill can lead to defective components. Extreme care is required to achieve total deburring and smoothing of the edges.
Bosch researchers are working to ensure that the chosen production method influences the material’s behavior. Quenching from the hardening temperature or the cutting of metal produce strains in the material. Various processes produce tensile and compressive residual stresses. But only the compressive residual stress increases a component’s dynamic strength.
For example, diesel direct injection common rail systems working with pressures of 1,600 bars are already on the market. In the coming years, systems working with 1,800 bars are being planned. And developers have their eye fixed on even higher pressures in their drive to make an engine’s operation cleaner and more economical. But the loading capacity of steel is reaching its limits. The highest strains occur in high-pressure bores and, in particular, in areas where two bores meet – at a so-called bore overlap. Here, there is a real danger that the material could tear. The component becomes defective. Bosch researchers are optimizing all parameters to prevent that from happening. First, the material:
An optimum degree of purity is necessary. Non-metallic inclusions such as oxides and sulfides found in all steel have to be drastically reduced because they lead to component failure. Second, the design: The angle at which the bores meet determines the stresses in the material. With the help of simulation, the angle can be selected in a way that minimizes the stress concentrations. Third, production: Even the slightest burr left behind by a drill can lead to defective components. Extreme care is required to achieve total deburring and smoothing of the edges.
Bosch researchers are working to ensure that the chosen production method influences the material’s behavior. Quenching from the hardening temperature or the cutting of metal produce strains in the material. Various processes produce tensile and compressive residual stresses. But only the compressive residual stress increases a component’s dynamic strength.
Determining the shape and behavior of a workpiece: The milling process in a simulation.
