Constantia Flexibles and watttron solve universal lidding challenge

A significant hurdle in transitioning packaging lines to mono-material solutions has been addressed as Constantia Flexibles and thermal technology specialist watttron unveil a new sealing approach.

The partners have successfully developed a single system capable of reliably sealing both polypropylene (PP) and aluminium lids onto PP cups, streamlining operations while supporting sustainability goals.

The initiative centres on integrating Constantia Flexibles’ PPCover, a mono-material PP lidding solution designed for enhanced recyclability, into existing high-speed sealing lines. While PPCover offers clear environmental benefits, achieving a consistent, high-quality seal without compromising efficiency or leading to material deformation posed a technical challenge in traditional systems.

Traditional sealing often involves heating the entire sealing head, which can expose the lid material to excess thermal stress and increase the risk of issues like curling. Recognising this potential inefficiency, Constantia Flexibles collaborated with watttron to find a more precise and adaptable method.

The solution leverages watttron’s proprietary ring-heating technology, which precisely applies heat only to the outer sealing ring. This targeted approach drastically reduces the thermal load on the rest of the lid material, ensuring uniform quality for both PP and aluminium while offering gains in energy management.

The system boasts rapid heat-up and cool-down rates—typically 10 to 20 °C per second — and maintains the set temperature with exceptional accuracy (±1°C). This capability allows the system to be safely powered down during production stops, contributing to energy savings of up to 50% compared to conventional sealing methods.

Lab-scale tests confirmed the efficacy of the approach, showing excellent peel behaviour and robust internal pressure resistance for both lid materials using the identical equipment setup.

Marcus Stein, CEO of watttron, emphasised the technology’s precision: “We developed our ring-heating technology to deliver precise energy exactly where it’s needed — no more, no less. That precision not only improves quality and flexibility, but also contributes meaningfully to energy efficiency in packaging lines.”

This universal sealing technology offers packaging converters and dairy manufacturers several practical advantages. It eliminates the need for maintaining separate machines or complex changeover setups for different lid materials, simplifying production and reducing equipment complexity. Furthermore, the system is compatible with 100% inspection capabilities, enabling real-time detection and removal of defective cups to maintain consistent product quality.

Claus Dworschak, market product manager die cut lids at Constantia Flexibles, summed up the impact: “This is a strong one-fits-all solution in dairy lidding. It simplifies operations and enhances quality — exactly what our customers need.”