Lanxess is in the process of launching a hollow-profile hybrid technology in which metallic hollow profiles are functionalized on conventional injection molding machines using plastic compounds. The plastic-metal composite components boast greater torsional stiffness and strength than could previously be achieved, according to the company.
“Hollow-profile hybrid technology has now progressed to such an advanced level that we have embarked on a variety of development projects with customers and have already reached the prototype stage with some of them,” said Dr. Matthias Theunissen, an expert in lightweight design at Lanxess. Potential applications in the automotive industry include cross car beams, coupling rods, stabilizers, and seat elements. In addition, the new lightweight technology could be used to produce skiing and hiking poles and components for furniture and the construction industry.
The hollow-profile hybrid technology is a further development of the “traditional” plastic-metal composite technology (hybrid technology) using sheet metal. The general strength of the new technology is that processors can manufacture with short cycle times, as is typical for injection molding in high-volume production. Further, auxiliary units or tooling technology are not required, which keeps investment costs low.
Preventing mold damage
Reasonably priced hollow profiles with relatively large dimensional variations can be used, further contributing to cost-effectiveness. “With the aid of innovative tolerance management, we can prevent profiles of that type from damaging the mold or stop leaks occurring in the injection molding cavity,” explained Theunissen. When the thin-walled hollow [metal] profiles are overmolded with molten plastic, high pressures often exceeding 400 to 500 bar occur in the cavity. As a result, there is a high risk of the profiles deforming or collapsing. “We have optimized the process such that the profiles withstand the pressures that occur and do not need to be supported from inside,” he added.
Weight saving of 30% for cross car beams
Lanxess offers highly reinforced polyamide 6 types such as the easy-flowing Durethan BKV60H2.0EF DUS060 for the hollow-profile hybrid technology, which has a short glass-fiber content of 60% by weight. With their high strength and stiffness, these compounds further enhance the performance of the corresponding components.
In a simulation study, Lanxess examined how using the compounds pays off in the design of a cross car beam. “The component can be designed with around 30% less weight than with all-steel structures, while offering better mechanical performance in some respects,” said Theunissen. Typical load cases and component properties were calculated, such as vibration behavior and the stiffness of the steering wheel in the direction of gravitational forces. “The component also underlines the huge potential of the technology in implementing cost-saving functional integration. For example, connections for the A-pillar as well as mountings for the steering column, dashboard, climate control units, and airbags were directly injected.”
New calculation models
Lanxess has developed new calculation models for the hollow-profile hybrid technology based on simulation tools that have proven successful for years in conjunction with “traditional” hybrid technology. These allow precise prediction of the production process and the quality of the connection between the metal and plastic. “With these tools we can, for example, accurately predict the maximum stresses hollow-profile hybrids will withstand and at what point they will fail. We apply this expertise in working with our customers,” explained Theunissen. A test specimen was used to validate the simulation, while extensive component testing for static and dynamic load cases underpinning the simulation results was carried out on real components.