Electric drives are becoming increasingly important in injection moulding, particularly with regard to energy efficiency. Hydraulic drives are not without their advantages, providing powerful injection capacities and cost efficiency. The ideal solution is to combine both drive systems, as the Allrounders from Arburg’s new generation of machines successfully demonstrate: the “Allrounder 470 H” anniversary machine is characterised by low acquisition and operating costs, a reduced carbon footprint and an energy requirement equivalent to that of electric machines.
The hybrid-driven injection moulding machines from Arburg’s Hidrive (H) series combine a precise electric closing unit with a dynamic hydraulic injection unit. The results of a visitor survey conducted at Arburg’s Technology Days in March 2023 confirm that the anniversary machine offers an attractive drive concept.
Among those surveyed, 96 percent thought that the new hybrid “Allrounder 470 H” was a suitable replacement for hydraulic machines, while 95 percent considered it to be a suitable replacement for electric ones. Gerhard Boehm, Managing Director Sales and Service at Arburg, explains, "The idea behind this machine technology was well received by visitors, as evidenced by the survey results. Respondents found the concept extremely interesting - for both technical injection moulding and demanding applications, for example in the automotive and packaging industries. Our hybrid anniversary machine, which comes in three performance variants, shows that we keep our finger firmly on the pulse. We have hit the nail on the head because it saves energy, conserves resources and is production-efficient, user-friendly and reliable all at the same time. In addition, most machine operators are familiar with hydraulic injection units and can benefit fully from their advantages."
Thanks to the integration of the servo motor manufacturer AMK Motion into the Arburg family, development and production of the entire powertrain can be handled in-house. This applies primarily to Allrounder injection moulding machines, including the inverter and motor which form the centrepiece of the closing system, but also to the mould technology, for example. The planetary roller screw drive in combination with liquid-cooled motors is ideally suited to high-end injection moulding tasks. Using this electric direct drive, which is integrated into the hybrid machines in the Premium and Ultimate performance variants, for example, all positions can be started up extremely quickly and precisely while achieving load-resistant power transmission and a high power density over a long service life, even when the machine is running at full load. The kinematics of the double five-point toggle system is optimally adapted to the electric drive. This provides for symmetrical force application during movements and mould locking, even with heavy moulds. The toggle can also be adapted with ease to different mould installation heights by means of a servo-electric adjustment system. Automatic clamping force regulation, which generates a consistent locking force and thus automatically compensates for the thermal expansion of the mould, is available as an option.
Homogeneous material preparation and precise injection are additional prerequisites for high-quality part production. Hydraulic drives have been a staple of injection moulding for decades and for good reason: they are sophisticated, robust, durable and low maintenance. They are particularly well suited to high levels of material throughput and generate high forces that can be maintained during any length of holding pressure phase. Depending on the performance variant, the hybrid Allrounders in the Hidrive series combine regulated injection, dynamic hydraulic accumulator technology and an energy-saving servo-electric dosage drive to achieve a high plasticising flow rate.
"The Comfort, Premium and Ultimate performance variants of our hybrid Allrounder are optimally adapted to their respective requirements," explains Guido Frohnhaus, Managing Director Technology & Engineering at Arburg. "This new generation of machines incorporates many technical innovations that are only available from Arburg. These include a new oil management concept, flow rate splitting and extended use of the Arburg servo hydraulic system."
The Comfort and Premium performance variants are equipped with the Arburg servo hydraulic system (ASH). With this technology, the drive system adjusts continuously to the actual power requirement thanks to a speed-controlled, water-cooled servo motor. One major advantage of this is that when the machine is at a standstill, the pump drive also stops, meaning no more idling losses. This ensures energy-efficient, low-emission operation and yields up to 50 percent energy savings, particularly for processes with long cooling times. Depending on the specific application, the Allrounder 470 H Comfort can save up to 12,000 kg of CO2 per year. At the same time, the machine’s cooling requirements and noise level are also significantly reduced.
As only serial movements can be performed with ASH technology alone, Arburg developed flow rate splitting to enable simultaneous movements. This function is integrated into the Premium performance variant. Thanks to the latest Varan valve technology with integrated sensor system, two hydraulic secondary axes can be driven independently at the same time, for example core pull and ejector during mould opening. The axes split the ASH servo pump’s available flow volume if required. The benefit is twofold: greater energy and production efficiency overall. This is because the machines consume significantly less energy and the cycle times are shorter. All this is possible without a hydraulic accumulator or multi-pump technology requiring a second servo motor and additional frequency converter.
The Ultimate performance variant of the hybrid Allrounder meets the highest requirements in terms of dynamics and process capability thanks to its hydraulic accumulator technology. All axes of motion can be independently controlled and driven by means of separate control valves. The hydraulic accumulator ensures a consistent pressure level. The result: quick, dynamic simultaneous movements and more process setting options, such as injection during mould closing or embossing.
The hybrid Allrounder machine in the Ultimate performance variant can reach injection speeds of up to 450 mm per second. "In the future, Ultimate machines will even be able to reach speeds of 550 mm per second, achieving accelerations of up to 1 G," says Guido Frohnhaus proudly.
Today more than ever, the injection moulding market is in need of adaptable modular drive systems that harness the benefits of both electric and hydraulic technology, namely speed and precision paired with power and dynamics. With the new “Allrounder 470 H”, Arburg has created a first on the market: a modern, cost-efficient hybrid machine that meets users’ needs now and in the future. Additional sizes in the Comfort, Premium and Ultimate performance variants will follow. The new, finely graduated hybrid machine technology is comparable to all-electric machines in terms of both dry cycle times and injection speeds. Arburg’s "new hybrids" are therefore an energy-saving alternative to hydraulic machines and an economic alternative to electric ones.
