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Better than glass

Polycarbonate is taking car manufacturing by storm. It is a lightweight, durable thermoplastic that can be molded into any shape. But a special coating process is needed to turn potential into end-product.

The desire for a car that expresses the driver’s personality has led to mass customization. As a result, the number of individual configurations is skyrocketing, and the role of automotive materials is changing. For example, windshields and windows have additional functions besides providing all-round visibility. Glass, in particular, is being used to create a specific visual impact, and stylish design is more important than ever. To achieve these goals, automakers are moving away from traditional silica glass, which is heavy and difficult to mold. They are increasingly turning to polycarbonate (PC).

Applications include majestic panoramic roofs and eye-catching all-PC deck lids on compact cars. Polycarbonate engine covers reduce the weight of Italian sports cars. And transparent console elements and decorative instrument-panel trim lend a touch of glamor to the interior. PC can be colored and tinted, and is easily molded into any three-dimensional shape. So it is a dream material for designers, letting them create roofs with, for example, integrated lighting, spoilers or antennas. For car manufacturers, the use of PC drives down component costs and streamlines production.

Polycarbonate is a transparent, colorless thermoplastic, and a familiar everyday material. It is employed to make CDs and headlamp diffusers, for instance. PC in its basic form is not as hard as glass, and more prone to scratches and damage from ultraviolent light. Only when it is specially treated to create a two-layer hard coating can its outstanding mechanical, thermal, acoustic and optical properties be exploited in new ways. PC‘s surging popularity is primarily being driven by the desire for lightweight construction in the automotive industry. More and more components are being made from plastic granulate by injection molding. The parts then undergo the all-important hard-coating process. Under cleanroom conditions, fully automated Eisenmann systems coat both sides with primer and a special hard-coating material. Simple components, such as B-pillar covers, are passed through a curtain of paint, resembling a fine cascade of water. Larger parts are coated by robot.

Hard coats are often a mere ten microns thick. But that is enough to make PC components resistant to scratches, climatic conditions, abrasion, ultraviolent light, and reactive chemicals. In addition, the coating process produces very attractive finishes that are as smooth as glass but far superior. However, PC’s most significant advantage is its lower density – identical parts in glass weigh up to twice as much. An average vehicle includes 4.6 square meters of glazing, and the amount continues to rise. Substituting silica glass, typically weighing six kilos per square meter, with polycarbonate makes a huge difference. Fuel consumption and particulate emissions are reduced, and vehicle dynamics benefit from a lower center of gravity. Polycarbonate also fulfils occupant protection and comfort requirements. It is chip- and impact resistant, does not shatter or splinter in a collision, improves passenger-compartment air conditions and absorbs ultraviolet and infrared radiation. In a nutshell, polycarbonate is like glass, but better.



Sven  Heuer


Eisenmann SE


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+49 7031 78-1522

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