xperion Ltd:
“Carbon fiber structures are increasing rapidly in industry”
In recent years, the use of carbon fiber in industry has increased significantly. Just ten years ago, the aerospace industry consumed the majority of all carbon fiber, but today the industrial sector already consumes about two-thirds of the carbon fiber on the market, reports Oulu-based xperion Oy. The company specializes in the manufacture and maintenance of composite rolls and structures. The German Inometa, which is part of the same group of companies, also manufactures aluminum and composite rolls for the printing and film industries.
“The aforementioned amount of carbon fiber corresponded to approximately 23000 tons of carbon fiber last year and consumption is estimated to double by 2015. Industrial components will increasingly utilize the advantages of carbon fiber composites, including lightness, high strength and stiffness, good damping properties, low thermal expansion and good corrosion resistance,” says Matti Pajala from xperion Oy.
Carbon fiber rolls have been used in the paper and printing machine industry since the 90s. Typical applications include guide and tension measuring rolls, vibrating breast rolls, spreading and take-off rolls, and doctor and application beams. Other industrial applications include drive shafts and other rotating machine parts, as well as various pressure vessels.
Carbon fiber consumption by main sector 2008-2015. Source: SGL Group market research.
Composite refers to a combination of two or more materials in which the materials interact with each other. Fiber-reinforced composites consist of reinforcing fibers and a polymer matrix that glues the fibers acting as reinforcements into a unified structure. In this way, the structure achieves properties that are much more than the sum of their individual parts. The most common fiber reinforcements in use are carbon or glass fibers. Correspondingly, epoxy or vinyl ester resins are most commonly used as matrix materials. The use of various thermoplastics and bio-based polymers as matrix materials has also increased.
Carbon fiber composite is about 80% lighter than a corresponding steel structure and about 40% lighter than a corresponding aluminum structure. It is therefore no wonder that the latest aircraft in the aircraft industry are already over 50% composite structures. Not only in the structures of rolling stock, but also in rotating machine parts, lightness is immediately beneficial, because the moment of inertia about the axis of rotation is directly proportional to the mass, so the required acceleration powers are lower or, correspondingly, the acceleration times are significantly shorter. In continuous acceleration and braking sequences, both energy and time savings are already significant.
Versatile material properties
“One of the most significant advantages of fiber-reinforced composite materials is the versatile controllability of their properties. A good example of a structure that can be achieved by controlling the stiffness properties of composite materials is the so-called double-shell roll structure, where the roll bodies are firmly connected to each other in the middle. The outer shell can be made significantly more flexible than the inner shell, even though its diameter is larger, which would be impossible with traditional materials. Such a solution is used, for example, in spreading rolls,” says Matti Pajala.
Typically, the damping capacity of carbon fiber composite is about 10 times that of steel. By adding special damping layers, the damping capacity of the laminate can be further improved. Good damping properties are an advantage, for example, in axle applications in transport vehicles, where replacing a steel cardan shaft with a carbon fiber composite has reduced vibrations and improved tire wear resistance.
Damping measurement of three cylindrical objects with identical geometry, steel on top (red), typical carbon fiber laminate in the middle (yellow) and carbon fiber laminate with a special damping layer on the bottom (green).
A low coefficient of thermal expansion and thermal expansion control are a significant advantage, for example, in conditions where the structure is required to maintain dimensional stability when the operating environment temperatures change. The typical coefficient of thermal expansion of carbon fiber composite is 1/10 that of steel and can be adjusted to zero if necessary, which can prevent deformation of the structure due to uneven temperature distribution.
For example, a steel roll stopped during a maintenance shutdown of a paper machine can easily experience such a situation as a result of thermal radiation, causing vibration problems and web breaks when the roll starts to rotate bent. This problem does not occur with a carbon fiber composite roll. The low thermal expansion coefficient is also used in various beam structures running across the paper machine, such as application and doctor beams, which means that special temperature difference compensation devices are not needed.
Through its excellent material properties and versatile manufacturing methods, carbon fiber is increasingly finding its place in industrial components where energy-efficient, lightweight and strong structures are required, says Matti Pajala from xperion Oy.
