FLEXflow servo driven technology for R-PET polymers
Hot Runner Systems with Optimized Design for Sustainable Applications in R-PET


The collaboration between Oerlikon HRSflow and Pezzutti Group, a leading supplier of thermoplastic molded resins, has resulted in the development of hot runner systems for the production of the "R-Box": a sustainable application in R-PET consisting of two elements, a box, and its corresponding lid for household use.


When innovation and material knowledge turn challenges into resources.


The fruitful collaboration between Pezzutti Group and Oerlikon HRSflow has successfully met the specific technical requirements of this application while also sharing an overall sustainable approach. Each 10L container is made from 29 recycled PET bottles. The R-BOX is currently produced 24/7, with total annual volumes exceeding 5 million pieces, confirming its widespread adoption.


Technical Challenges

Pezzutti Group in Pordenone presented two challenges to Oerlikon HRSflow for the production of stackable R-PET containers with lids, available in 4 sizes.


Firstly, the need to simultaneously manage two components of different sizes, especially considering that one weighs more than double the other. Secondly, the challenge of molding R-PET with the need to optimize cycle times. R-PET is a low environmental impact polymer, boasting the lowest carbon footprint among various recycled resins. It can be processed on an industrial scale, with possible validation for food contact. However, it presents a specific instability issue, making the molding process more complex compared to virgin material, often requiring frequent adjustment of molding parameters based on the rheological characteristics of the polymer used.


Hot Runner System Solution

The hot runner solution used, a hybrid hydraulic/electric system with 8 Ga series nozzles and 4 Aa series nozzles, has overcome the challenges presented by this application, both in terms of the complexity of the parts to be molded and the type of material.


The servo-driven FLEXflow technology, applied to a family stack tool, has allowed for optimal balance of the molded parts and a good aesthetic yield thanks to cooling bushings that enable constant temperature control in the gate area. This is crucial for managing the smoky color, prone to leaving visible marks and burrs at the injection point.


The system also features a specific configuration of the manifold and of the end ring, specifically studied for R-PET material, to avoid typical problems associated with this material during molding. Lastly, FLEXflow electric technology allows not only simultaneous filling of different parts but also independent management of each pin for the two pieces, with the ability to adjust opening time, speed, acceleration, and stroke length, ensuring efficiency and precision.


"After careful consideration of various market options, we chose Oerlikon HRSflow's FLEXflow electric system. This solution ensures flexible and accurate control of pressures and flow rates at each individual nozzle during the injection process, providing advanced functions for 360° process monitoring and optimizing cycle time," explained Daniele Boccalon, Technical Project Manager, who, along with Flavio Gomiero, R&D Manager, and the tooling team, managed the project at Pezzutti Group.


The Final Result: Sustainable 100% Recycled R-PET Containers for Household Use, with a capacity of 10 liters, a weight of 597 grams + 270 grams (lids), and a thickness of 2.5 mm.


Sustainability, an Essential Element


The collaboration between Pezzutti Group and Oerlikon HRSflow has been consolidated for several years based on the shared vision regarding environmental and sustainability issues. Pezzutti Group, with environmental certifications such as SGC class A and ESG rating 72, has a decade of experience in R-PET production. Currently, the Pordenone facility processes 90% recycled material, not only PET but also PP, APS. It has also installed a geothermal system and has a machine park with 170 presses – partly full electric – constantly updated to reduce consumption, utilizing 100% renewable energy.


This comprehensive vision aligns with Oerlikon HRSflow's commitment to researching sustainable materials for the future, as confirmed by Antonio Bortuzzo, President of the company. "We believe and invest in a sustainable approach. Recently, we purchased a specific injection molding machine to process R-PET, PCR, and biopolymers to be included in our test lab, which already has various machines with capacities ranging from 50 to 1000 tons. Despite the inherent complexity of managing sustainable materials, we are determined to invest in innovation, aiming to successfully combine the most advanced and market-demanded technologies with environmental protection."