ThinKing November 2018 – The new material H-CFRP makes hydraulic cylinders 70 percent lighter



Less energy is required to run the cylinders as the weight is reduced. And thanks to the material, you can forget about rust.

For the creation of its carbon composite material H-CFRP, Herbert Hänchen GmbH & Co. KG specially developed three technologies for the production of lightweight rods and pipes. The applications for the new material include the production of lightweight hydraulic cylinders. The resulting products are 70 percent lighter than steel cylinders. However, there are even more benefits: The reduced mass means that only half as much energy is required to operate the machines, the parts can withstand more acceleratory force and the material does not rust.

The Development Agency for Lightweighting Baden-Württemberg is presenting this innovation as its ThinKing for November 2018. Leichtbau BW GmbH awards this distinction each month to offer a platform to innovative products and services in the Baden-Württemberg lightweighting sector.

H-CFRP parts can be specially crafted for use in heavy machinery. These parts have an extremely smooth surface (surface roughness 1) and very tight tolerances (ISO 7). With properties like these, the material is perfectly suited for the use in hydraulic cylinders. This application requires a smooth surface to ensure that the parts form a tight seal and the tight tolerances ensure that the piston does not allow too much lateral motion and tips. The material’s low weight also enables significantly more acceleration and the energy consumption is reduced, for example hydraulic cylinders save by up to 50 percent energy.

Klaus Wagner, department director for research and innovation at Hänchen, explains that to develop the H-CFRP material, three new technologies were required to design the component, bind the materials and treat the surface. On the one hand, the challenge was to create round parts that could withstand great forces in three dimensions. “To realize this, we did research for new computation models and a suitable production process,” says Wagner. “Then we could define the number and type of carbon fibers according to the desired density and bend strength.”

Sealed surface protects against wear
For hydraulic cylinders, a strong bond between CFRP and metal must be created, for example for the use in the cylinder head. “In order to apply force to the carbon component, a metal piece is integrated during the production of the rod through a specially designed process. So we acn achieve much higher stress levels than it would be possible with glued joints,” explains Wagner. Furthermore, the surface must be as resistant as possible to friction wear. “CFRP is only partially suitable for fine mechanical processing. Therefore a hard, dense and wear resistant surface is created during the initial production phase of the CFRP which seals in the core material,” says Wagner.

Hänchen manufactures lightweight rods and pipes through a winding process – the so called filament winding procedure. This process produces products such as thrust rods in tooling machines or coupling rods in test benches. “The potential for savings depends on the application. In machine manufacturing in particular, true benefits can be found with composite based concepts as long as not just a single steel part is being replaced by CFRP, but rather the whole system is considered,” notes Wagner.

Use case: Silo cleaning made easy – even with 7 meter long poles
Hänchen produced 6.8 meter long handling poles comprised of two parts. These poles are used for cleaning silos for drying powder in the food industry. The problem: powder residue sticks to the walls of the silos and has to be swept off by hand. “This is where it makes a huge difference if one is working with six meter long poles made of steel or made of lighter carbon. Our lightweight version weighs only 1.5 kilograms in total,” says Klaus Wagner. This makes the poles easier to handle and less lifting force is required due to the lower weight compared to poles made of other materials such as steel. The end of the handling pole is fitted with an adapter made of aluminum which can be used to attach different end pieces such as brooms or hooks.

The surface can also be a key factor. Typically, wood poles were used that can easily break and are difficult to clean. “The CFRP poles on the other hand have a sealed surface which means they are suitable for use in the food industry. They are also very resistant to many chemicals,” says Wagner.

About Herbert Hänchen GmbH & Co. KG
The family owned company was founded in 1925 by Herbert Hänchen. In 1950, the company moved to the new headquarters in Ostfildern Ruit near Stuttgart. Today, Hänchen is still family operated by the third generation and has over 200 employees. The company is specialized in the research, development and manufacture of hydraulic cylinders and customized drive systems.
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