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Rapid Manufacturing Of Composite Thermoplastic Composite Materials: A Combination Of High Rigidity, Recyclability, A-level Surface And High Functional Integration

Jun 11, 2020

Evopro Systems Engineering Kft ("Evopro" for short) focuses on high-speed, automated composite material production for automotive applications in its research and development projects.

The company has further developed T-RTM technology for the production of structural composite parts based on PA6 matrix materials. The goal is to use in-situ polymerized T-caprolactam based on the principles of Industry 4.0 with the support of fully automatic preforming RTM technology.

It is undeniable that T-RTM technology has been well-known in some applications of overmolding/back injection, and some results have also been published in the past few years and demonstrated at the JEC World exhibition.

However, on this basis, Evopro has taken an important step in the framework of its project, creating a completely homogeneous sandwich structure with a PA6 shell and core material, thereby improving mechanical properties and recyclability. At the same time, Applying the PA6 in-mold coating creates a surface close to Class A on the part.

The sandwich structure is crucial for achieving high dimensional stiffness for low-density composite parts.

Generally, closed-cell structural foams such as PES, PET, PVC or PU foam, as well as balsa wood and honeycomb are used as core materials. The application of these core materials will bring difficulties to the recycling of PA6 based composite materials.

With this solution, PA6 foam core material can be used for PA6 based composite materials, thereby creating a homogeneous sandwich structure for optimal recyclability, which is an important factor for automotive applications.

The main advantages are:

►Recyclable homogeneous PA6 composite material structure interlayer meets high rigidity requirements;

►Recyclable composite material with homogeneous PA6 coating provides surface quality close to Grade A;

►Realize the automation and rapid production based on Industry 4.0;

►Higher functional integration for composite material parts;

►Reduce the cost of producing structural composite materials by 20%.

In general, due to polymer shrinkage and fiber print-through, the surface quality of continuous fiber-reinforced thermoplastic composite materials cannot meet the application requirements of the appearance surface.

For example, for SMC and other processes based on thermosetting materials, although in-mold technology is a known solution, the application of thermosetting coatings brings inhomogeneous material compounding, resulting in PA6 composite parts that cannot be Recycle.

With Evopro's process, PA6-based surface coatings can be created on PA6-based composite parts using in-mold coating. This process allows the use of different fillers, pigments, and additives.

The most important advantage is that the process creates cost-effective and recyclable composite materials that meet the basic requirements of the automotive industry.

This new development allows the creation of structural composite materials with a higher level of functional integration, such as higher structural rigidity (because of the interlayer), metal inserts, weldable and appearance surfaces (because of the in-mold coating), etc.

Based on these characteristics, in addition to weight reduction, it can also shorten the assembly and spraying time of composite parts.

The main structure of the sounding rocket produced using this technology has been shortlisted in the finals of the 2019 JEC Innovation Award car category.

The partners participating in the project are:

►Hungary eCon Engineering Kft

►Hungarian HD Composite Zrt

► School of Mechanical Engineering, Budapest University of Technology, Hungary, and the Hungarian Natural Science Research Center

Evopro showcased its innovations at booth 6-N4 of JEC World 2019.