Because of its good temperature resistance, impact resistance and aesthetics appearance, acrylonitrile-butadiene-styrene is often used in household goods and in the automotive industry. The development of a circular economy also shows successes.

Acrylonitrile-Butadiene-Styrene (ABS)

Elektronik

Automotive

Kunststoffe

Photonik

Optik

Polystyrol

Kunststoff Werkstoffe

Thermoplaste

Recycling

Umweltmanagement

ABS / ASA-Kunststoffe

Technische Kunststoffe

Kunststoff-Recycling

Kunststoffverarbeitung: Verfahren

Kunststoff-Aufbereitung

Sustainable Growth

Lightweight construction, functionality and design are characteristic of material development in all areas of application for PC compounds, composites and films. The range of materials has enormous opportunities when it comes to the mobility of the future, lightweight structural construction with continuous fiber-reinforced composites, 5G technology and medical technology.

Polycarbonate (PC)

Kunststoff

Bauwesen

Baustoffe

Medizintechnik

Polycarbonat

Medizinprodukte

Present in a Multitude of Trends

The transformation from the combustion to the electric engine entails several imponderabilities for the plastics industry. In part, electric drives have completely different material requirements which are becoming specifically evident with the increasing use of appropriate vehicles.

Flame Retardancy, Heat and Tracking Resistance of Electric Vehicles

Elektromotoren

Antriebe

Elektromobilität

Mobilität

Polyamide

Elektronische Bauelemente

Leistungselektronik

Hochleistungskunststoffe

Drivers of Electromobility

Injection molding is demonstrating its versatility again in the production of challenging optical plastic parts such as LED lenses for automotive headlights with tolerances in the micron range. A new development in multilayer injection molding allows productivity for the production of thick-walled lenses to be increased even further. 

Spritzgießen

Thick-Walled Lenses: Efficient Production of Thick-Walled Parts 

It is coming this way by giant steps – the K2016. Besides new materials, the materials makers will make it perfectly clear in Düsseldorf, Germany, that they are dealing intensely with global developments and challenges. This also involves taking stock of their global presence. 

How Materials Makers Turn Challenges into Chances 

Additive

Stabilisatoren

Pigmente

Tackling Tomorrow’s Problems Today 

With wide-ranging and specific property modifications, plastics can take more and more applications away from classic metal components. Polyamides and polyphthalamides, in particular, also are extending the performance spectrum, as two new variants show.

Two New Polyamide Grades Will Make Engineering Components More Cost-Effective

Progressive Metal Replacement

A wide variety of tailor-made compounds are used in LED technology. Appropriately matched plastics and fillers are used to achieve characteristics such as high reflectivity, translucence or thermal conductivity. 

Translucent and Thermally Conductive Compounds for Automotive and E+E 

Display im Automobil

Compound

LED, SLED, OLED

Tailor-Made for LEDs 

Styrenics can be polymerized using different technologies and it can be modified with a range of copolymers. The resulting plastics offer a wide range of properties allowing to customize them for different applications. Because of this range of properties they are suitable for many industries. Strong demand is for example driven by the automotive industry, healthcare and the packaging industry.

Styrenic Polymers

Verpackungsmaterial

Logistik

Styrol-Copolymerisate

Diverse Shapes and Applications

Threaded inserts ensure a secure connection of hybrid components. Under continuous load, effects can occur with thermoplastics due to pressure and temperature, which means that a durable screw connection is no longer guaranteed. Such effects can be prevented by thread inserts with a special surface structure.

Structuring of Surface Ensures Reliable Anchoring of Thread Inserts in Organic Sheets

Verbundwerkstoffe / Werkstoffverbunde

Faserverbundwerkstoffe

Andere Werkstoffe

Reduced Settling Behavior in Multi Material Components

The voltage test of the comparative tracking index is limited to 600 V so far. In many areas the voltages increase, especially for electrical vehicles. Therefore, it is interesting to know what the real limits of isolating materials are. These are considerably higher. To test these, a modified test set-up is necessary.

Testing Isolating Materials above 600 V

Prüfen von Kunststoffen

Messtechnik

Beyond the Limits of the Comparative Tracking Index

Batteries in electric vehicles must be specially protected to counter the risk of fires. Battery trays made from aluminum frequently offer insufficient protection.

Underbody Protection for Batteries in Electric Vehicles

Polypropylen-Platten

Halbzeuge und Zwischenprodukte

Kunststoff-Halbzeuge

Glasfasern / -matten

Verstärkungsstoffe

Aluminium

Metall Werkstoffe

NE-Metalle

Polypropylen

Polypropylene Beats Aluminum

Replacing metal with polyamides (PA) in components can not only reduce weight and costs, but also offers developers greater design freedom. However, this requires materials with improved mechanical properties.

Special Polyamides 6 Match the Properties of Polyamide 66

Metal Substitution with Improved PA

Marbling is often a real eye-catcher in plastic components. However, the effect is difficult to create and there are some pitfalls when it comes to reproducibility. Novel nozzles for injection molding machines in combination with a special dosing technology allow marbled molded parts to be produced far more easily in a much more robust process.

A 3D-Printed Nozzle and Modified Dosing Method Deliver Reproducible Marbling  in a Robust Process

Spritzgießwerkzeuge

Kunststoffverarbeitung: Maschinen und Komponenten

Werkzeuge für die Kunststoffverarbeitung

Dienstleistungen

Werkzeug-, Formen- und Modellbau

Additive Fertigung

Farben, flüssig

Exciting Design instead of  Exciting Manufacturing

Ambient lighting has captured the car interior – and facilitated orientation for the passengers. There is no need for anyone to fumble for the seat belt buckle in the dark in the Audi A7, as an integrated light guide shows the way. Kunststoff Helmbrechts produces the 3-component part and also developed the tool concept. The trick:  a so-called twin-turn tool which rotates on both sides. The company was awarded the GKV TecPart Innovation Prize for it at the K 2019.

Twin-Turn Tool Provides Solution to Production Problem with a Double Turn

Mehrkomponenten-Spritzgießen

KFZ-Zulieferer

Runway Lights for the Seat Belt

The use of extruded polycarbonate panels for the encapsulation of solar cells is opening up new areas of application for photovoltaics. These innovative modules are light in weight, can be readily machined and shaped with curved contours using the cold forming process. 

Extrusion

Solar Modules of Polycarbonate Open up the Third Dimension: Designed for the Sun 

Large-Area Curved Plastic Panels with Integrated Displays

Harmoniously integrating displays into the lines of a vehicle cockpit has always been a real challenge. Continental now uses a combination of film insert molding, in-mold decoration and injection-compression molding to produce large, three-dimensionally formed plastic panels.

The display increasingly sets the tone of a vehicle cockpit. Most current car models already have two full-color, graphic-capable displays. The instrument cluster usually consists of a large display (full digital cluster, FDC). In addition, there is usually a second display in the center console, which presents a wide range of content that is not directly relevant to driving, such as navigation, infotainment and operation. It often has a touch function. For years, the trend has been toward increasing the number of displays, as well as their diagonals and resolution.

Precisely harmonizing the technical properties of such side-by-side displays (white point, color temperature, color coordinates and black homogeneity) represents one major challenge. Another is to integrate the display surfaces harmoniously into the lines of a cockpit. Glass-based displays turn out to be somewhat intractable in this respect. The curvature that can be achieved is in the range from about 800 to 3000 mm radius. Flexible displays such as AMOLED (active matrix OLED) are significantly more promising. However, AMOLED displays must have a protective layer to make them suitable for the comparatively harsh use in vehicles with touch operation.

To solve this challenge, Continental has developed a continuous 3D plastic panel (Title figure). It protects the two 12.3 inch AMOLED displays that it covers against mechanical damage. In addition, the partially printed panel can be merged seamlessly into the surrounding surface, so that the entire curved surface acts like a single continuous instrument. To produce this special interior trim, multiple special production processes were combined with one another for the first time. So-called high-pressure forming (HPF) is used, e. g., for forming the two-dimensionally printed film to the three-dimensional contour of the final part. This is subsequently inserted into a mold and back-molded. This process is called film insert molding (FIM). With in-mold decoration (IMD), the hard coating is applied to the part while it is still in the injection mold in a roll-to-roll process. In combination with injection-compression process, this ensures very low stress conditions in the part. The technical challenge in developing this production process resulted from the dimensions of the panel: the displayed pattern measures around 200 mm x 700 mm. These dimensions cannot be processed by either IMD or FIM processes with >100 mm forming height. At the time of their commissioning, some of the machines used were unique in the world.

The 3D instrument panel is constructed of three functional layers. The reverse side is formed by a printed film (FIM) with 375 µm thickness, the front side is a 15 µm-thick hard layer, which is applied from a transfer film (IMD). The core of the part consists of 2.1 mm-thick polycarbonate (PC), which is injected between the FIM film and the IMD film at the front. It subsequently remains in the mold under homogeneous pressure and temperatures of initially 300 °C during the cooling phase. Despite the size of 200 mm x 700 mm, the roughly 2.5 mm thick end product only weighs 350 g.

This integration would not be possible without extensive technical experience with all the manufacturing technologies used. With the combination of all the steps, together with the three-dimensional contour of the panel, it is actually a completely novel process. Continental benefited here from its many decades of experience in printing and forming films, for example for the dials of traditional tachometers. The automotive supplier’s experience in injection molding optical and highly transparent components, such as mirrors for head-up displays and cover glasses was extremely important. The transfer application of thin films, too, has already been a large-series process for many years, for example for providing transparent indicator points with a luminous surface or producing high-quality piano black surfaces on plastic panels.

Besides the manufacturing technologies, another major challenge was the choice of suitable raw materials. The automotive sector actually makes very severe demands on the materials. They include heat resistance, for example to direct sunlight or the heat emitted from the displays, dimensional stability, scratch resistance despite numerous abrasion strokes and optical quality that must be comparable to high-quality materials such as mineral glass. High impact strength is also necessary in order to prevent splintering of the cover glass, even in the event of head impact in the worst case. In addition, it must also be possible to integrate touch operation. As with every lifetime component in the vehicle, a fatigue strength of over 10 years, or 300,000 km is expected – and has also been exhaustively tested. Only specially selected materials therefore come into consideration.

Figure 1 shows an overview of the two strands of the manufacturing process. The upper strand generates the printed reverse side of the panel by FIM; the lower strand feeds the transfer film with the hard coating. Where the two strands meet, the two film layers are backmolded by injection-compression.

At the beginning of the upper strand there is a large web of PC film (grade: Makrofol HF, supplier: Covestro AG, Leverkusen, Germany). The Makrofol HF is ideal for the purpose due to its high thermal resistance and transparency, as well excellent formability and elasticity over a wide temperature range. This 375 µm-thick film is first printed with functional and decorative motifs, as well as colored features, using a process combining digital and screen printing. Digital printing is used for creating challenging color gradients and graphic patterns. Even photorealistic prints can be implemented by these means.

In an HPF machine, heating tiles heat the finished printed 2D film webs up to its glass transition temperature of 150 °C. Then the heated web is positioned over the 3D mold and the forming mold closes. Air pressure at about 60 bar applies the film to the 3D contour of the mold (Fig. 2).

After removal from the machine, the formed film is cured under UV light. In the prototype production, the 3D blank is then trimmed to the part contour all round with a milling machine, and the required bores are drilled. This process produces the reverse side of the subsequent instrument panel. The HPF machine, from the manufacturer Niebling GmbH, Penzberg, Germany, allows genuine 3D forming of large-size parts with drawing depths of ≤150 mm at web sizes of 1150 mm x 650 mm. The forming tool was specially designed for this process.

On the lower strand of the production line in Figure 1, the transfer is prepared with the hard coating. This IMD film is fed to the injection-molding machine as roll material. With this manufacturing step, too, it was necessary to cross existing technical boundaries due to the three-dimensional and large-size design of the display panel.

Before backmolding, the printed 3D film is inserted into the complex injection mold. The two mold halves together weigh over 16 t. In addition, due to the complexity of the mold, it has a certain built-in intelligence in the form of a programmable logic controller (PLC), which, among other things, supports operation by smartphone via WLAN. The PLC is responsible for monitoring and coordinating the over 60 actuators and sensors that are located in the mold. It independently handles interplay with the injection-molding machine and two other secondary peripheries. During insertion of the FIM, the IMD protection film (type: Bright View; supplier Leonhard Kurz Stiftung GmbH & Co. KG, Fürth, Germany) is positioned in the mold by a special film feeder. To fix the film in the mold, a twelve-part clamping frame concept is used. This fixes the film in the mold using a precisely defined sequence of velocity and position control (Fig. 3). The transfer film is now laid wrinkle-free in the mold under vacuum.

When the two films have been positioned, the mold halves are closed and the films are backmolded with PC (grade: Makrolon Ai, supplier: Covestro) at up to 300 °C. Due to the high temperatures and pressures, the printed FIM and the transparent IMD protective coating become an integral part of the panel. To ensure that the subsequent panel has a uniformly high optical quality, the plastic is injected into the cavity while it is still slightly open, and it is then only closed fully after complete injection. This ensures a low filling pressure and a homogeneous pressure distribution during the cooling phase. Because of the resulting opening forces, the hydraulics of the machine must generate clamping forces of up to 1500 t. As the machine opens, the IMD transfer film is released from the front side of the 3D panel, while the hard layer (protective coating) remains on the PC.

The PC, with its glassy transparency, has high impact strength even at low temperatures and the good dimensional stability gives the 3D instrument panel its strength. After cooling, the IMD protective coating on the final panels is hardened under UV light. The sprues are subsequently removed and the panels are now ready for the optical dry bonding of the two 12.3-inch AMOLED displays.

Plastic panels allow additional 3D structures to be generated on the panel front side, which guide the driver’s fingers during operation of the center console (Fig. 4).

This allows digital operating elements, such as slide controllers for volume control to be replicated. These tactile orientation aids make good hand-eye coordination less critical. The driver can reduce the time he takes his eyes off the road, and maintains a better overview of the traffic situation. In addition, the 3D instrument panel can give the driver tactile feedback. For example, he feels it in his fingertips as soon as he has successfully performed a touch input. The visual check is therefore briefer or entirely unnecessary, which further increases safety. The instrument panel, which is 3D formed for design reasons, thus also supports ergonomic requirements on an operating interface in the vehicle.

The manufacturing processes, comprising FIM-3D forming, roll-to-roll IMD coating and injection-compression, allow large-size instrument panels with high optical quality to be produced. Besides their low weight, they possess many key advantages. First, the combined process allows the integration of curved display surfaces, which principally shifts the center control better into the arc of reach of the driver’s right hand. This makes the functions integrated in the center console display more ergonomic. The possibility of additionally generating three-dimensional structures on the surface of the panel makes operation during driving even safer and more intuitive. And finally, the process permits the seamless integration of individual AMOLED displays without visible transitions between the screen and panel surface. The result is a harmonious cockpit with attractive flowing curves. The innovative manufacturing technology with purpose-adapted machines has proven its effectiveness in the manufacture of prototype panels. The innovative process is therefore suitable for future series deployment.

Continental Automotive GmbH SV CC PR PP 

www.continental-automotive.de

Ausgabenartikel

Fig. 3. The twelve-part tensioning frame for positioning the IMD film ensures precision fixing of the film before backmolding

Two displays are seamlessly integrated into the continuously 3D-formed instrument panel

Fig. 1. The plastic panel is manufactured in two separate processes, which are then merged together

Fig. 2. The FIM machine for 3D heat forming of large-size polycarbonate arcs operates at 60 bar

Fig. 4. Surface topographies on the panel make blind operation of functions in the display easier

Continental - Hauptartikel

Martin Lenz is Expert Plastic-Design for Manufacturability and technical project manager for the 3D plastic panel at Continental; <a href="mailto:Martin.Lenz@continental.com">Martin.Lenz@continental.com</a>

Kai Hohmann works as a product manager for display products at Continental; <a href="mailto:Kai.Hohmann@continental.com">Kai.Hohmann@continental.com</a>

Read the German version of the  article in our magazine Kunststoffe or at  <a href="http://www.kunststoffe.de">www.kunststoffe.de</a>