The last ThinKing of 2020 is dedicated to a process with an impressive lightweighting potential: The injection blow moulding or “fibre injection moulding” (FIM) process uses three mould halves to manufacture components. It is an intelligent combination of material-independence and process-engineering expertise that yields components which are not only light in weight but also efficient in terms of cost and material use. This makes them particularly resource- and climate-friendly.
The Development Agency for Lightweighting Baden-Württemberg presents this innovation in its December 2020 edition of ThinKing. Under this label, Leichtbau BW GmbH provides a platform every month for new innovative lightweighting products or services from Baden-Württemberg.
At a glance:
“What do you need to make a component? The material, a mould and a way in which to fill it” – this is how Egon Förster, Managing Partner at Fiber Engineering GmbH, describes the initial thought process behind the development of the company’s fibre injection moulding (FIM) system.
Fiber Engineering uses fibres of different origins to produce three-dimensionally formed lightweight components that have so far found their primary application in the automotive industry. At first glance, the parts resemble moulded fibre mat blanks. However, the manufacturing process does not require the intermediate step of creating a semi-finished product.
In the first process step of FIM, the fibres are blown directly into two mould halves; the cavity is then homogeneously filled with fibre volume content. In a thermal process, the fibres, which are on average around 1 to 140 millimetres long, are then compressed, bonded and formed to create the component. The binders used are thermosetting or thermoplastic binders that are added in form of either fibres or a powder. Alternatively, the component can be infiltrated with resin, as with resin transfer moulding (RTM). Depending on individual requirements, the mechanical properties of the component can be adjusted locally via its density, i.e. via the fibre volume content and the compression of the third mould half.
Efficient use of materials with financial and environmental benefits
Fibre injection moulding (FIM) allows for a material input of up to 100%, meaning that the moulded parts can be manufactured already with their final contours. Production offcuts can be significantly reduced or even eliminated.
“This is an important aspect, as material costs often account for up to 70% of total costs in the automotive industry,” Förster explains, emphasising the cost-conscious approach of the process. Thanks to the specific density settings and the elimination of waste, material costs can be reduced by an average of 20-30%.
The components are also significantly lighter in weight. „In the case of a seat belt cover cap for cars, we were able to achieve a weight saving of 50%, while also reducing material costs by 50%,“ Förster reports on one of the company’s automotive projects. FIM components can have a variety of mechanical properties. They can be designed to be either hard or soft – depending on the respective material and density, this allows for the manufacture of parts ranging from hard supporting parts (door modules or dashboards) to soft insulation or padding.
Seats that are comfortable as well as sustainable
In regard to seat padding, the fibre injection moulding process is in direct competition with conventional PUR manufacturing processes. And here, too, the lightweighting potential is considerable: Savings of up to 30% are possible for seat padding and backrests, whether for aircrafts, cars, railway vehicles – or even baby carriers.
In contrast to foamed components, the fibre injection moulding process is better suited for cases in which it is necessary to comply with strict requirements regarding CO2 emissions or pollutant content. This is important in regard to baby carriers, but also presents an advantage for the automotive industry, as the carbon footprint of the vehicle can be reduced through the use of natural fibres, for example for backrests.
With the exception of adhesive fibres, the FIM process can be used to process a wide range of materials – from carbon, basalt and plastic to natural fibres such as wood, wool, hemp or even seaweed.
In addition, the raw fibre material can contain a high percentage of recycled material. The system is so robust that it can even accommodate problematic fractions of recycled material. Fibre injection moulding thus helps to conserve resources and reduce CO2 emissions. Moreover, the components themselves can be recycled at the end of their lifecycle.
Suitable for large-scale production
Many projects are currently under development that rely on natural fibres or recycled materials to meet the requirements for reducing CO2 emissions.
In the US, the FIM process was recently used for the first time in a large-scale production run. At the time, 10 kilograms of fibre were used to manufacture the bulkhead and floor insulation for the Volkswagen Passat. Every 90 seconds, the two parts were finished simultaneously to become one vehicle set.
About Fiber Engineering GmbH
Fiber Engineering develops 3D moulded components from staple fibres using the FIM fibre injection moulding process, which has been patented in over 30 countries worldwide. The company’s service offering for interested users incudes product development with PT tools, parts production for small series, serial tools and series machines for medium- or large-scale production.