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17th May 2018, Nijverdal

TenCate maximises recyclate in new laminate

The new material format enables designers of composite components to add more complex features. © TenCateTenCate Advanced Composites has developed a new reinforced thermoplastic laminate that incorporates recycled materials and offers processing and design advantages.

A key advantage of thermoplastic composites over their thermoset counterparts is their recyclability, the company says, but there are not a lot of real world applications for the recyclate, despite the fact that the process, in essence, is not difficult, involving  grinding the materials down and applying heat and pressure to make parts.

TenCate is looking to maximise the recyclate’s economic and technological value and thus its applicability in real-world applications.

Grinding and remoulding does not often make a lot of sense economically and is essentially a form of downgrading – dramatically shortening fibre length and mechanical properties. TenCate is working to solve these issues and make recycling of its materials available and useful to customers. In this case, the focus has been on closed-loop recycling with excess materials that are the result of the value chain as it exists today.

The new material format of continuous carbon fibre reinforced thermoplastic laminates that are enhanced with a flow layer of discontinuous fibre, either from virgin or recycled thermoplastic composites, enables designers of composite components to add more complex features and benefit from the optimised material performance of continuous fibre reinforced laminates, maintaining a robust and cost-efficient stampforming process.

The enabled features encompass edge sealing and local strengthening or stiffening of the part. Stiffening ribs, textures, and variable thicknesses are also possible, as well as local bosses to spread strains induced by fasteners.

With recycling excess material (e.g., nesting surplus and trimmings), and using this material as a flow layer in the end product, a balance can be created between supply and demand of recyclate.

Smart part design enables an engineer to near a 100% “buy to fly” ratio, and reduce the thickness of the base material laminate needed to achieve the desired performance.

As a result, the blanks can be tailored to dramatically reduce the amount of material needed. The flow layer consists of

high fibre volume fraction, long fire reinforced bulk moulding compound, which can be supplied on the laminate or can be added locally prior to the stampforming process.

The stampforming process itself is conventional – the laminate can be stampformed to shape in short, less than five-minute thermoforming cycles.

The mechanical performance of such tailored parts can be drastically improved while decreasing part weight. The flow layer allows for the design of stiffening ribs in corners and in the flanges, bearing strength by the addition of bosses around the drilled holes and thickness variations in the base laminates. The mechanical performance is optimized due to the inherently good interface between the laminate and reinforcing features.

Apart from the obvious advantage of using less material to produce a part and decrease weight, this way of production makes it possible to use recyclate directly at the source where it is created. This creates a balance between the supply and demand of recyclable materials and limits the carbon footprint of the recyclate by eliminating scrap transportation. Furthermore, it provides a means to a tightly regulated industry, such as the aircraft industry, to keep on top of material traceability.

The key advantages of the recycled flow layer-enhanced laminates are:

  • Better performance to cost ratio.
  • Improved performance to weight ratio.
  • The ability to achieve complex composite geometries.
  • High potential for improving buy to fly ratio.
  • A balanced usage of recycled materials.

This technique combines the unmatched performance of continuous fibre products, either fabric or UD tape reinforced, with the superb mechanical properties and design freedom of long fibre reinforced bulk moulding compound. Tailoring local stiffening, strengthening, and functional features can reduce the average laminate thickness and thus component weight.

Recycling excess material from previous processes in the part as the flow layer potentially increases the degree of utilization of purchased material, the so-called “buy to fly” ratio up to nearly 100%.

The fast, robust, and cost-effective conventional stampforming process can be used for part manufacture, with no expensive tooling or equipment investment required.

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