E-Mobility: Lightweight Design Magnesium Engine Housings for Light E-Bikes
Magnesium engine housings are increasingly being used in the production of e-bikes. By replacing aluminum with magnesium, significant weight savings can be achieved, thus improving the functionality of the e-bikes.
The advantages of magnesium are obvious: Compared to aluminum, magnesium has a 33% lower density and scores as the lightest construction metal with a weight saving of 28%. Considering the growing trend towards lightweight design, it is therefore no wonder that the electromobility industry also wants to take advantage of the positive properties of the metal. Magnesium is currently experiencing a real boost in popularity, particularly in the manufacture of e-bikes - or more precisely, engine housings.
Casting of Magnesium Components
Magnesium is a reliable material that can be used profitably and in a resource-saving manner. As the seventh most common element on earth, the raw material is not only available in sufficient quantities, it also causes low emissions and can be recycled. In times of ever-increasing environmental protection requirements, these are forward-looking properties that will enjoy great popularity in foundries in the long term. As the material is lighter than aluminum, magnesium has emerged as an attractive alternative to aluminum in recent years, so that today die cast components made of magnesium are installed in numerous vehicles. However, urban mobility components are now also produced by die casting or thixomolding.
The world's first magnesium e-bike housing and cover was cast by the European manufacturer Cast Werk, who also operates the world largest thixo-moulding machine (1.250 mt clamping force) to produce such parts for a new urban mobility. A further producer of such parts is Stihl using die casting with unique die casting machine technology, who is also well known for their high quality power tools.
User Advantage through Easy Handling
The use of magnesium in e-bikes is also noticeable on the end user's side, as the weight savings achieved make the electric bikes easier to handle. On the one hand, lightweight models allow for an improved ride, while on the other hand they are easier to transport and park. In order to meet the demands of use, manufacturers are constantly making optimizations.
For example, Bosch has equipped its newly developed Performance Line CX 2020 engine with a magnesium housing that weighs around 25% less than its predecessor, at approximately 2.9 kg. The new engine allows mountain bike manufacturers to achieve better frame integration and shorter chainstays, which together with the weight reduction should make future models more agile and maneuverable.
The Brose Drive S Mag e-MTB drive has also achieved a significant weight reduction by manufacturing the motor housing from magnesium instead of aluminum, unlike the Drive S. In a comparative test conducted by E-Mountainbike Magazine, the drive was praised in the category design/weight, among others.
Further Weight Saving Potential
In addition to the use of magnesium engine housings, the weight of e-bikes can be reduced by using other lightweight components. Thus, frame structures and wheels also have great growth potential. Already in the production of a conventional children's bicycle, Zhenjiang Li, Hebi Jianglang Metals Co., Ltd. was able to win a prize in 2019 by developing a lightweight magnesium frame, which represents a kind of technological breakthrough over the traditional welding of iron and aluminum frames. The AM60B/AM50A alloy used helped to optimize the function of the part, i.e. low weight and better shock absorption were achieved. These effects can certainly also be achieved on e-bikes.