The Mercedes SLK has them, as well as the Bugatti Veyron, the Smart fortwo, the Honda Civic and the Seat León: windows made of polycarbonate (PC). Besides electric drive systems, the current environmental discussion involving cars focuses on the reduction of fuel consumption.An increased use of polycarbonate windows is the way to reduce the weight of the car—together with other lighter components.
BBG has taken note of an increased demand for tools for finishing vehicle windows made of plastic. For the finishing of car windows, BBG has become specialised in the processes of encapsulation with polyurethane (PU) and insert moulding with PVC, TPE or other elastomers.
Glass finishing for over two decades 
For over two decades, BBG has been developing and producing tools and mould carrier systems for the PU encapsulation of laminated glass. For seven years, BBG has been expanding its offer to include procedures for insert moulding glass with TPE and PVC, and has been producing the necessary injection moulding tools. Due to our broad know-how, it was an obvious subsequent step to also expand the range of services to include the encapsulation and insert moulding of polycarbonate windows.
Up to 65 percent weight reduction
But even if polycarbonate windows have been continuously on the rise for some time in the automotive industry, glass still can't be used everywhere. Still, the future lies in this technology. With up to 65 percent weight reduction compared to glass windows of the same size and thickness, they are able to make a contribution to lowering fuel consumption and CO2 emissions. Because while glass has a density of 2.77, that of polycarbonate lies between 0.9 and 1, meaning over half the weight reduction even with thicker PC windows. An additional plus of polycarbonate glass is that it's particularly impact-resistant, increasing the passive safety of vehicle occupants.
That's why, thanks to the great degree of design freedom, polycarbonate is preferred more and more over conventional glass for fixed triangular windows, side windows and sun roofs. In both cases, the following holds true: In order to ensure an aerodynamic, soundproofed and impervious transition to the car body, the window must be enclosed with a soft component, meaning encapsulation with polyurethane or insert moulding with a thermoplastic.
Insert moulding is more cost-effective with large-batch production
Although the tools for insert moulding are more complex and expensive, the PVC or TPE used with them is over 50 percent more cost-effective than polyurethane. For this reason, insert moulding of PC with thermoplastics makes more sense economically with larger batch sizes. Since here—contrary to PU encapsulation—release agents are unnecessary, the process can be largely automated, which increases profitability. PU encapsulation of PC is preferable for small-batch production, while offering additional advantages through greater design possibilities and simpler processing of complex glass moulds.
Cost optimisation already in component design
Already during component design, the question of whether to use glass or polycarbonate takes centre stage, as well as what OEM specifications must be fulfilled and whether encapsulation or insert moulding makes more sense from a qualitative and economic point of view. In a cooperation venture, starting at an early stage the component can be designed jointly with the client such that all available possibilities for cost optimisation are taken advantage of. This allows, for example, the planning of multi-cavity tools for finishing left and right side windows in one work step.
Based on the component dataset obtained, the tool can then be constructed in CAD. For injection moulding tools, simulated filling studies contribute to the optimisation of injection points, weld line, filling time and interior mould pressure. Findings obtained through the simulation are decisive for the condition of the tool—it is crucial in order to produce it in optimum quality.
One-source quality from A to Z
After the client's approval of the design, we produce the tool, which is tested and sampled under conditions similar to serial production in our internal test centre. The in-house production machines for injection moulding and finishing with polyurethane are an important element for BBG in order to be able to achieve consistently high quality throughout the entire production process of a tool. This makes BBG the only company known to us in Germany that offers tools for encapsulation and insert moulding of both laminated glass and polycarbonate windows from a single source, from A to Z.
