Hot runners jump to the fast lane

In recent years, injection molders have seen a massive increase in value for money in hot runner systems. In part, this is due to decreasing prices resulting largely from more suppliers in a less-than-stellar market for molds. But even as prices are reined in, technology is advancing in leaps and bounds, as evidenced at NPE.

Improvements incorporated into Mold-Masters' (Georgetown, ON) Master-Series encompass faster color change, improved uptime, and superior part quality. Company president Jonathon Fischer claims the nozzles are fully leak-proof, due to Master-Seal-a seal at the nozzle-manifold connection that relies on a thermal expansion coefficient much higher than that of the surrounding steel-and Visco-Seal, which uses the melt itself to form a film seal between the tip and mold gate. The nozzles' Endura tips have a Vickers hardness of more than 3200, compared to 1200 in earlier designs. Corrosion resistance is said to be more than 10 times greater than with carbide tips. As for fast color changes, Fischer says with the new nozzles, the number is as low as 18 shots per change.

Accu-Valve addresses improved gate cosmetics. Pin alignment is optimized by isolating the effect of manifold thermal expansion on the valve pin. Double-shouldered gate geometry ensures pin centering.

The Stack-Link is a new solution for melt transfer across parting lines on stack molds. It eliminates drooling and stringing while managing a complete self-sealing shut-off with minimal pressure drop. The Pivot-Link is for molding such parts as instrument panels and multicolor automotive lenses where gating on angled surfaces and multiple custom manifolds are required. It rotates through three axes and has an adjustable pin height.

At Husky Injection Molding Systems (Bolton, ON), marketing VP Jeff MacDonald says development of the company's latest range of Pronto quick-delivery systems-which now include Ultra 1000 nozzles for large parts-yielded improvements that are being applied elsewhere. Valve gate products have been redesigned to improve alignment both back and front, and a new combination of materials improves thermal balance and wear. More than 5 million cycles without wear in the gate area are reported.

There have also been nozzle and tip design improvements in hot tip products that provide a much broader (three to four times) window than before. MacDonald says temperatures can go much higher before stringing occurs, and much lower before freeze-off. An advantage is faster production startup.

Synventive Molding Solutions (Peabody, MA), meanwhile, is reviving the Kona name that had virtually disappeared after Dynisco's hot runner business merged with Kona and Eurotool. Kona specialized in nozzles incorporating heat-pipe technology originally developed by NASA. Now Synventive has launched the Kona XP system for general purpose applications. It combines heat-pipe nozzles with more conventional multizone manifolds. Various nozzle designs-open-bore and valve gate-can be used. Kona SP targets single-stage injection stretch blowmolded PET container production.

Ewikon Hot Runner Systems (East Dundee, IL) introduced several additions to its HPS III range. MV multi-tip nozzles for vertical gating are in versions for direct connection to the machine nozzle or for use in manifold systems; MH1 and MH2 multi-tip nozzles are for open and direct horizontal gating; the K nozzle, for commodity materials used in packaging and medical applications, has sealing in the shaft area to simplify mold construction; and the Slimline S nozzle, with a 4.5-mm flow channel diameter, is targeted at advanced packaging and medical applications.

The new Precision Series of valve gate hot runners from Fast Heat Inc. (Elmhurst, IL) is for parts requiring good surface finish and uses a new design that incorporates a guided tip and pneumatically actuated shut-off pin to provide a more streamlined and uniform delivery of melt to the cavity.

Peter Mapleston [email protected]