HOT RUNNERS | TECHNOLOGY
positioning of each individual pin can be precisely adjusted via the oil flow rate. The company says that HyFlow uses a controller with a user-friendly interface to set the lock position of each individual pin. The opening and closing speed for each nozzle can be set by a manual adjustment mecha- nism. This allows for controlling the melt flow rate in a way that cascade injection moulding results in a uniform mould filling process without sudden pressure drops and the associated surface defects. The positioning of the pin also allows for optimal balancing of the pressure distribution in the cavity during the entire injection process. Hyper-GF hot runners are now available for
processing abrasive thermoplastics. The new Hyper-GF series, available for use with HRSflow’s Ga and Aa nozzles, is designed to improve the long term performance of the hot runner system when processing highly abrasive materials such as glass fibre reinforced materials. It supports extended service lives, even in injection moulding processes with high productivity. Contributing factors include the use of special steels and an optimised flow channel design.
HRSflow has also been involved in a pilot project with film manufacturer Kurz to show how Flexflow Evo for servo-electrically driven valve gate systems can be used to achieve good results when back- moulding sensitive films. The Flexflow Evo hot runner system for film insert moulding (FIM) enables the integration of capacitive films for sensors or touch control panels in combination with backlit decorative films. This provides a new design and functional flexibility, particularly for automotive interior applications. In cooperation with Kurz, a film featuring functional capacitive elements for touch operation and decorative elements was back-injected with clear polycarbon- ate in a single step, enabling backlighting in the area of the operating elements. HRSflow says that the servo driven valve gate technology produced results at a quality level that would not be achiev- able with conventional concepts. In particular, after back-injection, the thin functional and decorative elements do not show internal stress as in conven- tional cascade injection moulding, due to the evenly and low-pressure spreading melt flow front, while any damage to the film was reliably avoided.
AM manifolds Hasco has developed Streamrunner additively manufactured manifolds for hot runner systems. The company first used additive manufacturing for hot runner manifolds in 2016. Since then, Hasco says that it has been building further on its initial
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experience and can now offer mould makers and injection moulders further freedom in design, and high-quality injection mouldings with the lowest possible shear stress. Using Steamrunner technol- ogy, the company says that flow channels can be configured with the optimum rheological layout, avoiding sharp edges and areas with poor flow. The gentle passage of the melt through the manifold makes for considerably lower shear stress in the material, resulting in better quality mould- ings, says Hasco. The flow-optimised design also speeds up colour changes, because the melt can be divided and deflected over generous radii. The absence of diverting elements means the Stream- runner can be produced in a particularly compact design. Tight spacing down to 18mm is also possible for high cavity systems, depending on the application in question. The height of the manifold can also be restricted to 26mm, making it consider- ably smaller than other manifolds. Other advan- tages include that it is also suitable for high cavity systems and is leak-proof. With many complex injection moulded parts,
undercuts or recesses cannot simply be demoulded in the main demoulding direction, Hasco adds. Movable built-in components in the tool enable the injection moulded article to be removed from the mould without damage. A wide variety of different types of slide elements are used. Hasco says that the slide units Z18185 allow new ways of designing tools. The type of actuation enables a shape to be built up without complex and space-consuming bores for inclined columns for slide actuation and allows high force absorption. Associated core inserts Z18186, in materials 1.2343 and 1.2360 with different hardnesses, are available for individual contouring. The slide units, which can be easily installed from the parting line, offer the largest possible contour area with the smallest possible
HyFlow from HRSflow, which controls the needles’ opening and closing speeds in hydraulically actuated cylinders, is available as a complete or – when applied to selected actuators only – as a hybrid version
November/December 2020 | INJECTION WORLD 47
IMAGE: HRSFLOW
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