E-mobility is quiet. Background noise caused by vehicle components is undesirable here. Schunk has developed a new powder metallurgical process that produces gears with a noise-damping effect while saving weight and costs.

Materials scientist Johannes Heyde explains how these advantages are achieved and for which components the process is suitable. As project manager Innovation, he is the contact person for customers and development partners when it comes to high-strength sintered parts.

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Mr. Heyde, how do you achieve the noise-reducing effect of the powder metal gears?

Johannes Heyde: Our Silent Gears are pressed from metal powder in a new process and have a porosity of up to 10 percent. This porous structure helps dampen sound and thus produce less noise.

But doesn't the porosity mean that the components are less strong?

Johannes Heyde: We often hear concerns that our material might be less strong than conventional forged materials that our customers have been working with for decades. We can counter this by saying that the material is at least as strong as a result of the post-compaction process stage. Of course, we also have material parameters from fatigue strength tests which we can present in diagrams in an easily comprehensible and convincing way.

What else distinguishes the new process?

Johannes Heyde: Our process offers the unique possibility of combining several - normally incompatible - properties in one gear. The result is components that have different properties in terms of geometry and material in different areas. For example, a very hard and strong toothing area to reduce wear, and a main body with excellent damping behavior.

Do customers have to expect higher costs for the new process than for conventional production?

Johannes Heyde: On the contrary. Powder metallurgy is known as an extremely cost-effective process. One reason for this is its high suitability for large-scale production. We can produce high volumes with the process, which not only saves time, but is also cost-efficient. Innovations have to overcome high hurdles, especially in the automotive industry. Only when suppliers can prove that processes are ten to 15 percent cheaper will they open up to new technologies. Here, too, our test results help us to prove the efficiency of the process.

At what volume is the new process profitable compared to conventional machining?

Johannes Heyde: That always depends on the size of the parts and their complexity. For large and complex parts, our process can be profitable from around 30,000 pieces per year. For smaller parts, the new process is worthwhile for quantities of 100,000 parts per year or more.

Are there any restrictions in terms of part size to be suitable for the process?

Johannes Heyde: Our process can be used in a wide range: from small parts weighing a few grams and with a diameter of 5 to 10 millimeters to large parts with a diameter of 300 millimeters. Basically, we look at each request individually and advise our customers on the possibilities.

For many companies, environmental aspects are becoming increasingly important. They are a strong selling point. What about this?

Johannes Heyde: With our manufacturing process, we consume 60 percent less energy overall. This makes powder metallurgy one of the green technologies, because we don't have to use any primary raw materials for powder production. In addition, we use almost 100 percent of the material, because no more chips are produced, as is the case with subsequent mechanical processing. As a result of the efficiency of the entire process, not only do our customers benefit from performance-enhanced "quiet" gears, but so does the environment.

Advantages of powder metal gears at a glance

• Reduced Noise Vibration Harshness (NVH).
• Up to 10 percent weight reduction at a performance level of solid steel
• Better CO₂ balance thanks to energy- and
  cost-efficient process

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