View of San Francisco from an airplane window

© istockphoto/franckreporter

A perfect view above the clouds

There is a growing trend towards ever larger airplane windows. For this reason, Evonik has commissioned the world’s most cutting-edge stretching and polishing line for aviation materials made from PLEXIGLAS®.

In Weiterstadt, in the German region of south Hesse, the company now produces stretched sheets of polymethyl methacrylate (PMMA) in lengths of up to 5.4 meters and widths of up to 3.7 meters, making it the largest available sheet format worldwide. Compared to cast PMMA materials, stretched PMMA sheets have improved impact resistance and increased chemical stability, making the material ideally suited to fulfill the strict requirements of the aviation industry.

Stretching and polishing line for aviation materials made from PLEXIGLAS®

Production started

Before production can actually begin, the company must successfully pass an expansive and strict external validation, as the products must first receive an aviation certification due to the strict regulations of the aviation industry. At the same time, the first partners in the aviation industry can inspect the new material, allowing them to see the advantages of the large-format PMMA sheets for themselves. Alongside greater freedom of design, the advantages include a particularly efficient production process and less waste.

© Evonik

Evolution in Acrylics is our Passion

This topic is a fine example of what “Evolution in acrylics is our passion” – the vision of Evonik’s Acrylic Products business unit – expresses, and what Evonik means by smart concepts in the chemical business. Read more about why evolution is part of the DNA of PLEXIGLAS®, why passion is so important in new projects, and how Evonik’s expertise will advance the development of this material in the years to come.

The trend is clearly towards larger cabin windows in commercial airplanes,” says Martin Krämer, Head of the Acrylic Products division at Evonik. With its PLEXIGLAS® brand, the Essen-based company has been one of the leading manufacturers of aerospace materials for more than 80 years. The fact that the brand acrylic glass is used in aerospace production is due to its high optical quality, low weight and good processability. In addition, PLEXIGLAS® is considerably more durable than glass and weighs only half as much – two factors that are particularly important at high altitudes.

Full-service provider for the aerospace industry

A special type of PLEXIGLAS® is used in airplanes and helicopters. In simple terms, this means that certified sheets from cast PLEXIGLAS® are elongated or stretched in a highly elaborate and complex process. The advantage of stretched PMMA sheets is that they have improved impact resistance and increased chemical stability.

Explanatory film: How do airplane windows become robust?

Evonik already ranks among the leading manufacturers of the primary product needed for stretched plates. With the new plant in Weiterstadt, Evonik will also be able to stretch and polish the sheets at its own facilities for the first time – including sheets that are considerably larger than was previously possible. The Acrylic Products division at Evonik will thus become a full-service provider of cast and stretched PMMA sheets for the aerospace industry. “This was the next logical step for us. It enables us to effectively pursue our strategy in the performance materials segment,” explains Krämer. “It helps us shore up our position as the leading manufacturer of polymer materials and intermediates. Building on our strong relationships with our customers, we will contribute to shaping their business and set new standards in our markets.”

Large glazing made from a single piece

When windows and cockpit windshields in airplanes and helicopters are to become larger, there is no way around producing stretched PLEXIGLAS® sheets in the largest size possible. Full-glazed machines and panoramic windows in airplanes may still be some way off, but the airplane manufacturer Boeing has already started by enlarging the windows of their current Dreamliner model by two-thirds. “Being the largest in the world, our format of stretched sheets paves the way for new designs of extra-large glazing and improves the efficiency of smaller cabin windows,” explains Roland Mickal, Head of the Transportation market segment in the Acrylic Products division at Evonik.

Did you know...

…that there’s a tiny hole in all airplane windows, regardless their size? The breather hole ventilates the window and is used to prevent the windows from fogging up due to moisture accumulating between the outer, middle and interior pane. Instead, the moisture can escape through the breather hole. In addition, the hole regulates the pressure between the outermost and middle interior pane, ensuring that the window does not break.

Easy to process

In addition to being the ideal solution for ever larger windows and cockpit windshields, the extra-large stretched sheets also mean that manufacturers of conventional airplane windows can produce more windows than before from a single stretched sheet. The result: increased yield and improved efficiency. And airplane manufacturers can rely on the quality of PLEXIGLAS®. Thanks to the new sanding and polishing process, the stretched sheets have a considerably better thickness tolerance compared to current materials. This reduced thickness tolerance means that the end product, i.e. the airplane window, will be easier to process and considerably lighter “These improved features in stretched PLEXIGLAS® are an outstanding added value for customers that Evonik offers in addition to the product itself. This is a great example for what the Evonik Performance Materials segment means by smart chemicals business,” says the regional manager of the business segment, Martin Krämer.

With our new stretching and polishing plant, we will once again position ourselves as an innovative partner to our customers

Martin Krämer
Head of the Acrylic Products division at Evonik

Optimally prepared for the trend

“By investing a two-digit million figure into our new stretching and polishing plant, we are setting new standards and affirming our position as an innovative partner to our customers – fully in line with our vision “Evolution in Acrylics is our Passion,” says Krämer. A look into the future clearly shows that PLEXIGLAS® is on the right track. According to estimations, approx. 30,000 new passenger airplanes will be needed by 2031, as the PLEXIGLAS® aviation expert Mickal explains: “Clearly, there definitely is a high demand for high-quality stretched PMMA sheets by PLEXIGLAS®.”