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Automotive Thermoplastic & Natural Fiber Composites on the Move!

Donald Rosato – Nov 21, 2017

Advanced Composites for Automotive Lightweighting TechnologyBreakthrough thermoplastic composite (TPC) technology that has outstanding strength-to-weight performance is meeting tough new restrictions on carbon dioxide emissions and weight reduction through metal replacement.

Similarly, Natural Fiber (NF) compounding composite knowhow is making inroads into:

Let’s take a look at some versatile thermoplastics and natural fiber composite solutions that don’t just help with lightweighting, but offer many other benefits...

But before we start; it would be interesting to note that it’s the use of higher amount of advanced composites as compared to other components that leads to lightweighting in automotive. The figure below shows the same.

Significance of Advanced Composites
Advanced Composites Lead Automotive Lightweighting

Now let's turn our attention towards the latest developments in advanced composites:

DuPont’s Vizilon TPC

DuPont’s Vizilon TPC product family is comprised of continuous-glass fiber woven reinforced consolidated sheets based on Polyamide (PA, nylon) 66/6 blends and higher heat polyphthalamides (PPA). The sheets can be stamped or thermoformed into various shapes, which can then be overmolded.

In addition, the company offers various specific over molding resins based on PA6, PA66 and PPA. DuPont is also developing unidirectional (UD) tapes. UD tapes unit costs are lower than fabric sheets. But, there are extra challenges like: Placing tapes in molds and holding them in position during over-molding unless they are converted into preforms first in a separate process.

DuPont Vizilon TPC Automotive Oil Pan Design
DuPont Vizilon TPC Automotive Oil Pan Design
Apart from weight saving virtues, DuPont also highlights the crash absorption potential of Vizilon TPC. It absorbs more energy than metal and also performs better in crash applications than other engineered thermoplastics.

A Vizilon TPC beam measured a five and a half times energy absorption increase versus a short-glass fiber equivalent plastic beam. It also sees potential in large structural items such as floor pans that require lightweight and stiffness. Metal to TPC conversions will take time with safety-critical components. Automotive OEMs (Original Equipment Manufacturers) will require fully proved out design, manufacturing, assembly, and cost parameters.

DuPont is emphasizing lower cost glass fiber versus carbon fiber. Upcoming CO2 emission standards are looming, starting in Europe in 2021 where the fleet average CO2 emissions target by new cars will be 95 g/km (grams/kilometer), which is 40% less than the 2007 fleet average of 158.7g/km. This in turn is putting pressure on OEMs to reduce vehicle weight that will lead to a large-scale adoption of TPCs over the next two years.

The KraussMaffei cell

A little different from injection molding, equipment supplier KraussMaffei has designed a production cell producing parts using thermoplastic resin transfer molding. The parts use continuous fiber reinforcement impregnated with nylon 6 that is polymerized with an in-mold reaction mixture (in-situ) from caprolactam.

The KraussMaffei cell, making a roof shell frame for the Roding Roadster R1 sports car, took preforms produced at composites equipment specialist Dieffenbacher’s Preform Center. The Roadster roof frame is based on a hybrid construction of fibers in conjunction with plastic and metal. This makes it possible to process both glass and carbon fibers with reliability. KraussMaffei’s production process lasts only a few minutes. The system thus demonstrates the feasibility of automated and process-reliable integration of metallic loaders into Thermoplastic Resin Transfer Molding (TRTM) components. The individual steps add up to a complex but a concurrently cycle time optimized process.

The four sub-preform parts along with aluminum and steel inserts are first positioned on a measured gauge layout followed by:

  1. Rriveting a steel insert into a sub-preform
  2. Continuing, a handling robot positions the aluminum bracket and the preassembled hybrid components in the TRTM mold
  3. Then caprolactam nylon 6 monomer is injected and it cures into thermoplastic nylon 6 plastic
  4. Finally, the handling robot removes the finished component

This near net shape approach takes the part close to its final roof frame form, and thus eliminates the need for complex post-mold processing such as milling the part edges.
KraussMaffei Cell
KraussMaffei In-Situ Polymerized Nylon Composite
Roof Shell Frame

Lanxess Tepex TPC Brake Pedal 

A production available TPC component is the luxury car brake pedal for the Volkswagen Group’s Porsche Panamera NF and Bentley Continental GT. This Lanxess Tepex Dynalite part has recently won a Society of Plastics Engineers (SPE) Automotive Division “Body Interior” category award!

Lanxess Tepex TPC Brake Pedal Center Arm 
Lanxess Tepex TPC Brake Pedal Center Arm
Here are some of its key benefits:

  • The brake pedal is half the weight of a similar steel part
  • It can also be manufactured in large-scale series production using a cost-effective one-shot process
  • Meets the high load requirements thanks to the multi-axial fiber layer construction of the Tepex insert

Lanxess subsidiary Bond Laminates uses a Tepex Dynalite that is a fully consolidated semi-finished product with a thermoplastic matrix reinforced with layers of continuous glass fiber fabric.

The brake pedal incorporates overlays aligned in the longitudinal direction and several woven inner layers with fibers aligned at ±45°. Required high tensile and flexural strength is in the outer overlays, with the inner layers providing high torsional performance.

The component is manufactured using a one-shot hybrid molding process that integrates shaping of the Tepex insert into the injection molding. The injection overmolding material is Durethan BKV 60 H2.0, nylon 6 from Lanxess reinforced with 60% short glass fibers.

Elix Polymers' ABS NF-based Compounds

Sonae Arauco’s Woodforce engineered wood fibers have been compounded into Acrylonitrile Butadiene Styrene (ABS) by Elix Polymer producing NF reinforced injection molding compounds. Elix’s goal is to create a more sustainable product line. Their NF compounds have very good flowability, uniformly fast mold filling even in thin wall parts, and extremely low in mold fiber degradation.

These new ABS NF-based compounds are attractive to the automotive industry where up to now PolyPropylene (PP) has been the plastic used with natural fibers. Automotive applications include door trim and loudspeaker cover interior parts. The wood-like NF appearance provides interesting color and surface texture designs.

Elix Polymers' ABS-NF Renault Kadjar Front Grille
Elix Polymers' ABS-NF Renault Kadjar Front Grille

In semi-structural parts like center console carriers, ABS-NF can replace glass-fiber (GF) reinforced ABS. Mechanical properties of the two materials are very similar, with Elix’s ABS-NF less dense, at 1.12 g/cm3 versus 1.15 g/cm3 for ABS-GF. ABS-NF recycles easier, better retains its properties after multiple molding cycles due to lower fiber size reduction. Good heat stability (Vicat B50 test (load is 50 N) of over 100°C) goes hand in hand with high surface quality, and it more than meets automotive OEM emission requirements.

Faurecia's Hemp Reinforced Polypropylene

Finally, automotive Tier One supplier Faurecia has improved its Nafilean 20% hemp NF reinforced polypropylene for injection molding through its joint venture (with French agricultural cooperative Interval) compounder Automotive Performance Materials. The novel Nafilite compounding process incorporates micro-cellular foaming that provides enhanced part weight reduction.

Faurecia Foamed Nafilite NF
Faurecia Foamed Nafilite NF Weight Saving Instrument Panel Cellular Cross Section

Nafilite was recently given the JEC World Paris Sustainability Innovation Award. It is being used in the Alfa Romeo Giulia instrument panel. The foaming technology provides a 30% weight saving over equivalent injection molded structural parts. In total, the combined weight saving, renewable natural fibers use, and recyclable polypropylene roughly decreases environmental impact by 30%.

Furthermore, it reaches the quality standards of automotive OEMs. Also, the micro-cellular structure provides better finished product quality in terms of robustness, fit and finish, and mechanical properties versus standard materials.

Automotive Professionals: Stay Alert!

Stay updated on latest advances in automotive lightweighting technology to identify where the true potential & new opportunities exist for you and make better R&D decisions. Join the course: Automotive Lightweighting Solutions: Thermoplastic & Natural Fiber Composites.

Automotive Lightweighing Solutions

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