HOT RUNNERS | MOULDS
The nozzle features a round body which has been reduced in diameter by 15% compared to the standard version, and extended tip inserts are used. Consequently, the space available between the nozzle body and the part contour is considerably increased and can be used by the mould maker to integrate optimised cooling sur- rounding the cavity, as well as effective mould venting. Both parameters allow particularly efficient production due to reduced cycle time and improved filling. The company adds that the heated nozzle body is combined with a nozzle retainer, which is available in different lengths. This design allows a variation of the immersion depth of the nozzle, so that long parts can be positioned without any prob- lems. An adapter nozzle feeds the melt into the nozzle body. It sits under the manifold, passes through the nozzle retainer without touching it and ends in the nozzle body. The mouthpiece of the adapter nozzle is pressed against the nozzle body and seals on its face side at operating temperature. This guarantees leak-proof melt transfer. The HPS III-MHR111 nozzle comes in three versions for simultaneous gating of two, four or eight parts. In addition to the standard tip insert where the tip points in a 90° angle to the demould- ing direction, a tip insert with a 60° angle is available. It allows the gating point to be posi- tioned closer to the parting line of the mould. Like all nozzle types within the HPS III-MH nozzle range, the HPS III-MHR111 nozzle features tip exchange technology for ease of maintenance. The tip inserts are easily exchangeable on the machine from the parting line with no need to dismantle the mould. Ewikon has also introduced the L2X-Mikro hot runner system, particularly designed for the production of small parts with shot weights from 0.05g on small injection moulding machines. The company says that it allows the reliable processing of a broad range of materials including technical resins. The system is available in three standardised compact layouts with two, four or six nozzles and fits the most commonly used mould sizes for small injection moulding machines. Furthermore, the compact manifold dimensions of 61×48mm enable the problem-free integration into smaller mould designs, for example, for Babyplast micro-injection moulding machines. The compact system layout is an advantage for applications with small shot weights. Since the total flow path lengths in the sys-
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tems can be kept short and there is only a small melt volume that needs to be exchanged, thermal sensitive mate- rial can be processed without problem. The slim hot runner nozzles feature powerful direct heating. Despite the small outer diameter of 10mm and the flow channel diameter of 3mm, a compact coil heater with thermocouple has been integrat-
ed into precise cut-outs in the melt- bearing pressure tube. This design enables stable heating with minimised loss resulting in an even temperature profile along the whole length of the nozzle and improved heat input in the
gate area. Consequently, the constant high thermal performance required for the process ensures reliable processing of technical materials. The nozzles have a leak-proof screw connection with the manifold. The L2X connecting technology uses a special connecting nut which allows free rotation of the nozzle and the connecting cables until it is finally tightened. The precise cable alignment achieved using this technology further minimises the required installation space. The new hot runner system is optionally
delivered as complete hot half or as ready-to-install unit with pre-installed nozzles. Since the leak-proof connection between nozzles and manifold eliminates the need to have a defined pre-load to seal the system, simple and time-saving drop-in installation is possible. HRSflow has developed a new valve gate solution - the HPgate - that is designed to increase the process window and improve quality of the moulded part without flash. The company says that the gate is machined on a hardened metal insert that is screwed into the mould, making it easy to replace in the event of wear. The design saves the mould maker the time-consuming and complex machining of the standard cylindrical gate. In addition, with the gate geometry already being machined on the insert, difficulties connected with the cylindrical configuration including narrow tolerances, large and variable depths and providing coaxiality between needle and gate are eliminated. Due to the hardness of the insert, a steel of reduced hardness can be chosen for the mould plates. In addition, there is special needle geometry in
Left: The HPS III-MHR111 nozzle from Ewikon is specifically designed for the efficient production of long tube shaped parts, such as
syringes or pipettes
Above: Six-drop hot runner system for small injection moulding machines from Ewikon
November/December 2017 | INJECTION WORLD 57
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