Moldmaking Report – Hot Runners: Problem solved

Recent developments in hot runner systems specifically address the shop floor concerns of processors: how to regain valuable floor space, cut time-to-market and reduce downtime.

Nozzle innovations have addressed three common issues: leaks, thermal loss and the need for closer spacing.

Mold-Masters is using plastic as a defense against leaking plastic with its new Visco-Seal technology for its standard hot runner tips. During the injection molding cycle, the Visco Seal causes a thin plastic membrane to form between the actual seal and the mold. The plastic membrane solidifies in this gap and prevents molten material from flowing back and around the nozzle seal. Mold-Masters reports the benefits to the customer are reduced need for inspection, disassembly and cleaning due to plastic leakage. The company has tested the Visco-Seal on a variety of thermoplastics, including ABS, polyamide, polycarbonate and polypropylene.

Less heat transfer to the manifold and gate insert is one benefit of the new Ultra 750 nozzle from Husky Injection Molding Systems Ltd. Better heater coverage on the nozzle contributes to the improved thermal performance of these nozzles. Heat loss to the gate insert is reduced by 73% compared with Husky’s older 750 Series nozzles.

The Ultra 750 is part of a family of Ultra nozzles that will be introduced this year. It uses a tip insert and retainer design, with a stainless steel retainer that ensures a reliable seal in the gate insert. The Ultra 750 achieves throughput of up to 250 g/sec, suitable for medium to large parts.

The need for tighter spacing is addressed by Heitec’s Miniature hot runner valve gate system. Drop spacing as low as 7 mm is possible with these small, flat nozzles. The valve-gate system has on-site replaceable heaters and thermocouples. The melt flow channel is beside the guided needle so that melt restrictions and dead corners are eliminated.

Quick delivery catching on

Standard hot runners with short delivery times are a hit. Steve Morris, vice-president, hot runners, of Husky Injection Molding Systems, reports a large increase in sales of the company’s Pronto hot runners. The Pronto program provides rapid delivery of fully-configurable, complete hot runners. Pronto offers 120 plate sizes that match the majority of D-M-E, Hasco, Omni, National and Futaba mold bases. “We continue to update the flexibility of this line, and we’ve improved the design of models designed for Hasco mold bases,” says Morris.

D-M-E offers Meteor hot runner systems for the quick-delivery market. The Meteor3 hot half promises delivery in three weeks. One-day turnaround is available for Meteor1 systems, which consist of an off-the-shelf manifold with a machined main flow channel. The customer machines the nozzle locations and end plugs. Meteor1 is stocked in in-line and X patterns, for two-drop and four-drop applications. Other components needed to build a hot runner system, including nozzles, supports, nozzle seat, locating ring and thermocouples, are also available to ship the same day.

Synventive Molding Solutions’ MultiZone (MZ) hot runners are now available for delivery in as little as four to five weeks. MultiZone uses heaters on both sides of the manifold to distribute heat more evenly for better quality parts. The MultiZone systems are customized, with drawings available within 48 hours of request.

Shrinking controllers

In hot runner temperature controllers, a couple of options are available to ease the floor-space crunch.

One of the most popular features of the new TTC family of hot runner temperature control systems from Gammaflux is availability in “panel mount” configuration, reports the company. The panel mount system allows the temperature control system to be used by any injection molding machine as a direct tie-in to the machine’s regular control panel, eliminating the need for a separate hot runner control cabinet.

The Altanium Series breaks new ground as the only modular, small-footprint solution that can support from 1 to 384 zones, says manufacturer American MSI Corp. The company says Altanium can control the highest number of amps per square foot of space utilized. Altanium is fully-scalable, supporting up to 384 zones with a single controller design and user interface. Mold set-ups can be saved and loaded for rapid configuration and duplication between manufacturing cells.

Remote operation of the console is possible for Mold-Masters’ Temp-Master TMMZ controller. The controller uses advanced touch-screen technology that includes point and set control modules, and touch and rotate 3-D perspective graphs. The compact multi-zone controller is capable of a much higher load per zone than typicaly units. TMMZ can handle a load of 16 A per zone — 60% greater than the typical 10 A ceiling. Feedback since the unit was introduced at K’ 2001 indicates the system is reliable and robust.

Synventive Molding Solutions has expanded its line of hot runner temperature controllers to the include the new RMC and RMB microprocessor-based, single-zone models. Particularly noteworthy is the ability to allow safe removal and replacement of modules without shutting down mold power, due to a proprietary power interrupt system. Both units are compatible with existing G+ and D-M-E G series mainframes.