Hot news in runnerless molding.

Hot News in Runnerless Molding

There's lots of news to report from almost all suppliers of hot-runner components and controls. Higher power and response speed in controls is one theme. There are also new approaches to obtaining precise and uniform gate-temperature control to run either high-temperature engineering resins or especially sensitive materials such as rigid PVC or acetal. Compact systems for high-cavitation molds--including one new entry capable of gating up to 10 cavities from a single bushing--and others taking new approaches to optimize part cosmetics also number among recent product introductions.

In addition, some suppliers are broadening their lines to include both high- and low-voltage components. While 220-v systems remain the most common, some suppliers favor much lower voltages for burnout protection and thus lower maintenance. On the other hand, some suppliers say low-voltage systems also require a faster-cycling controller.

HIGH-SPEED CONTROLS

Blazing speed and beefed-up power capability are said to distinguish the new FITT-8000 from Barber-Colman Co., Loves Park, Ill. It will supersede the company's FCS-8000 hot-runner controller (see PT, Aug. '89, p. 70), and is different in many respects, says product manager Roy Choster. Like the FCS-8000, it can stand alone or be interfaced with the MACO 8000 machine controller. (In the future, it will be possible to interface the FITT-8000 to other makes of machine control via the SPI Communications Protocol.)

Each compact FITT-8000 module is a compact, single-loop-dedicated controller with 30-amp capacity. Not only does this meet current 30-amp automotive specifications, but it allows complete freedom--unlike some competitive systems, according to Chostner--to assign 30-amp power to any desired zones, up to a total connected load of 25 kVA. As many temperature-control loops as the mold requires are serviced by several mainframe housings with interconnected power cables for connection to one 240-v a-c power source. While all wiring and connectors for power are sealed, redundant NEMA enclosures, step-down transformers, and disconnect interlocks are offered as prewired enclosures.

One variation of the FITT-8000 system is a compact frame of only 24 x 11 x 12 in., capable of 25.2 kVA and containing six 30-amp temperature-control modules with integrated scr power drivers.

Besides high power and flexibility, extremely rapid control response for maximum precision and safety are also key distinguishing features, says Chostner. Each module measures the sensor input every 12.5 millisec, and initiates an scr output every 50 millisec. At this cycle rate (reportedly one of the fastest on the market), the heater does not have time to cool down before it's told to heat up again, prolonging its life, Chostner says. He also notes that this means the controller can both detect a short circuit and shut off power to the heater within 8.3 millisec. And he adds that, unlike most controllers, the FITT-8000 can instantaneously alarm on the loss of one of several heaters connected in parallel.

A single FITT-8000 module starts at $570, including load and thermocouple connectors Barber-Colman's Coordinate Overcurrent Protection (COP). (CIRCLE 59)

Gammaflux, Inc., Sterling, Va., has improved the stability and responsiveness of its temperature-control instruments by standardizing on fixed-tuning, broadband controllers, according to president Michael Stein. He says these have demonstrated the ability to run any load encountered in hot-runner molding. "Conventional PID controllers are narrow-band and depend on optimum tuning for control stability," Stein explains. "It's virtually impossible to optimally tune a hot-runner zone manually because of the very long time constraints involved, and automatic tuning is inconsistent at best. One can try to minimize control instabilities by lowering the gain (amplification of error), but this makes the controller unresponsive to shear heat and other mold cycle effects," says Stein. He contends that Gammaflux's stability minimizes temperature cycling to produce the most consistent parts, often at faster cycles. (CIRCLE 60)

As reported last month (p. 115), Husky Injection Molding Systems, Ltd., Bolton, Ontario, now offers fixed-tuning temperature controllers built by Gammaflux under a private-label agreement to complement Husky's hot-runner systems. Single-zone modules have 30-amp capacity, and four-zone versions 3 amps/zone. (CIRCLE 61)

American MSI Corp., Newbury Park, Calif., is now offering a version of its ATC-System hot-runner temperature control for low-voltage d-c systems. President Tim Triplett says the ATC-LV controls 12 to 96 zones of low-voltage d-c heaters or any mix of high-voltage manifold circuits with low-voltage circuits. The ATC-LV has a color graphic display for viewing setpoints, actual temperature, power output, and zone status of up to 20 zones per page. The display permits the viewing of up to 96 zones per page, depending on number of parameters displayed for each zone. (CIRCLE 62)

The Data Acquisition and Computer Systems Div. of Syscon International, Inc., South Bend, Ind., has introduced two brand-new features on its year-old Model 530 HR hot-runner controller (see PT, Aug. '89, p. 69). One is integral statistical process control (SPC) capability, which communicates to a separate IBM-compatible personal computer running Syscon's new and reportedly easy-to-use SPC software, introduced this spring (see PT, May '90, p. 15). This optional software can accommodate form eight to 2304 control loops or data-acquisition channels (i.e., from multiple 530 HR units of 8-24 channels apiece), collects both process and dimensional data simultaneously, and provides an on-line overview display. All displays are color-coded, highlighting out-of-control conditions and other factors on control charts and histograms.

Secondly, communications software for the 530 HR now also supports the SPI protocol, allowing the hot-runner control to be integrated into the total machine control package. (CIRCLE 63)

Gunther North America Inc., Bolton, Ontario, a relatively new branch of a West German manufacturer, has a new multizone temperature controller, the FP 13, capable of controlling up to 13 zones with a processing time of 10 millisec per channel. Full digital PID control is provided, plus a number of enhanced software features, including "soft-start" protection against moisture-induced short circuits, and controlled warm-up whereby the controller brings the entire hot-runner system up to setpoint temperature at a rate governed by the slowest-heating zone; this reportedly could help prevent resin degradation in the nozzles, which may heat up faster than the manifold, owing to the smaller mass of steel, says engineering manager Paul Boettger. For large molds requiring more than one 13-zone controller, the zones can now be numbered continuously for user convenience, rather than repeating a 1-13 numbering on each controller. He adds that the controller can now be used with both 5-v and 220-v hot-runner components from other manufacturers besides Gunther. The controller is said to be particularly economical, starting at less than $4000 for a 220-v, 10-amp system. A step-down transformer for 5-v operation costs extra. (CIRCLE 64)

NOZZLES FOR HIGH-HEAT RESINS

Gunther recently added 220-v versions to its previous line of 5-v components. Boettger says a combination of both systems (220-v manifold and 5-v nozzles) offers optimum performance for molding high-temperature resins, including PEEK, which requires melt temperatures of 750-800 F. Gunther's system has been used to mold thin-walled seal rings of PEEK with direct gating as small as 0.03 in. diam. Boettger attributes this capability to the open-bore, unrestricted flow within its system, providing low pressure drop, and to an insulated heating system (no external heater bands to cause thermal expansion problems) that maintains a uniform temperature profile right down to the probe tip.

The latter feature has also proven successful in molding nylon without drooling. This recently enabled Gunther's system to replace a valve gate in molding mocrowave dishes of nylon 66 filled with 15% mica. An armored tip on Gunther's nozzle solved the problem of rapid wear on the valve gate caused by the abrasive material. (CIRCLE 65)

Echoing a similar theme, Orycon Control Technology, Inc., Ocean, N.J., has introduced a new heated Sprue bushing that's said to prevent freeze-offs at the gate and nozzle seat area, even with high-temperature materials. According to v.p. Sal Benenati, the key feature is an internal torpedo located in the middle of the flow channel, which carries heat to the extremities of the bushing. It was designed to avoid "blow-outs" that can occur if both ends of the flow channel solidify and the mid-section overheats, causing degradation of the plastic and generation of high-pressure gas, creating the potential for injury. Prices range from $356 to $668. (CIRCLE 66)

Incoe Corp., Troy, Mich., has also addressed the problem of not overheating engineering resins by introducing Thermal-Tips for its XRC bushing line. Thermal-Tips combat the problem of temperature variations in runnerless molds by controlling temperature at the critical gate end of the bushing, making it possible to raise or lower the temperature of the melt just before it flows into the mold. This is said to be especially important in intricate part molding. Each Thermal-Tip is thermocouple-controlled and is separate from the main bushing heater. (CIRCLE 67)

Spear System, Inc., Camarillo, Calif., reports an interesting new high-temperature application for its thermal-gate system, which also is said to be the first application of computer-controlled nozzle sequencing. Sadaplast Americas, Inc. in Spartanburg, S.C., recently installed the Spear system in a vertical-clamp, reel-to-reel injection molding system for encapsulating a continuous-strip electronic lead frame with Phillips' Ryton R-10 PPS resin. Built for Airpac Corp. of Frederick, Md., the system reportedly can mold 2000 parts/hr with a 15-sec gate-to-gate cycle time.

Computer-controlled sequencing, developed by Sadaplast, uses a fiber-optic "electric eye" to search and scan a continuous lead frame just ahead of the system's eight-cavity mold. The computer stores the position of any blank frames in an onboard computer and automatically sequences the Spear probes on or off in any combination of cavities to avoid blank inserts whenever they enter the mold. The system thus eliminates wasting other good parts on the strip, and cuts labor and material costs dramatically, according to Sadaplast president C. Kenneth French. "In addition to Spear's ability to skip a part and be on again for the very next shot, it gives a full shot to specification after not sequencing up to five times consecutively," says French. He also praises the Spear System's ability to handle the abrasive, glass and mineral-filled PPS compound. (CIRCLE 68)

FOR HEAT-SENSITIVE RESINS

Kona Corp., Gloucester, Mass., has been working extensively with resin suppliers and others on applications for its heat-pipe hot-runner systems with heat-sensitive resins like rigid PVC (see PT, Aug. '89, p. 67). After installing over 30 PVC systems in the field, Kona has now configured certain common requirements for these systems into a standard hot-runner package for PVC. It features all-stainless-steel construction and specially sized runner channels and manifold bushing tips with specially designed inserts to accommodate the shear sensitivity of PVC. The package also includes a Kona stainless-steel machine nozzle to ensure heat-pipe control of melt-temperature uniformity from the barrel of the machine to the mold cavities.

Sales manager Bruce Fishman says it's still necessary to minimize residence time when processing PVC, and recommends purging with a suitable material prior to shutdown. The Kona design provides access to flow channels and bushings so that when the resin does degrade, maintenance can more readily be provided. (CIRCLE 69)

Kona has also been working with Du Pont Co., Wilmington, Del., on processing acetal, another heat-sensitive resin. Fishman says tests have shown that Kona's externally heated, open-bore design is well suited to this type of resin. (CIRCLE 70)

COMPACT MULTICAVITY SYSTEMS

Also new from Kona are the HT-50 and HT-150 Hot Runner Systems. These manifold systems are prewired and preassembled into the "A" side of the mold. They're recommended for high-cavitation and closure, cap and medical applications. The systems feature individually heated bushings for shutoff control. (CIRCLE 71)

Ewikon N.A. Inc., Concord, Ontario, has introduced a high-cavitation (32 or more) hot-runner system for small parts that employs a new hot-tip design capable of gating up to 10 cavities per tip, reducing the number of control zones required while maintaining a balanced system.

The hot tips fit into a very small mold base, reducing the size of injection machine required. For example, an 80-cavity mold with a mold base of only 12 in. x 24 in. reportedly will produce 40,000 parts/hr on a 40-ton machine. A 160-cavity mold with a base measuring only 20 in. x 24 in. is said to produce 80,000 parts/hr on a 150-ton machine.

Ewikon's hot-runner systems incorporating the new hot-tip design cost about half as much as would the company's previous system for the same size mold. At the same time, the new tips allow for slightly larger cavity spacing, where needed, than previously. Both side-firing and conventional gates are available. (CIRCLE 72)

A.L.B.A. Enterprises, Inc., Torrance, Calif., representative for the Enrietti Thermoplay system from Italy, has introduced a valve-gate system with a compact cylinder for close spacing of cavities, which is operable by either air or oil. Other news from Enrietti includes the introduction of 220-v nozzles (complementing its 7.5-15 v systems), for which it is also offering a new programmable, voltage-proportioning, microprocessor controller. (CIRCLE 73)

D-M-E Co., Madison Heights, Mich., has introduced a nozzle for fast-cycling, thick or thin-walled parts and applications requiring frequent color changes. Called the Gate-Mate 4 Nozzle, it's the fourth in D-M-E's Gate-Mate line of thermocouple-controlled nozzles for use with the D-M-E Hot One externally heated runnerless system. V.P. Robert Priebe says the nozzle profile is compact, permitting shorter centerline distances for smaller molds and increased cavitation in larger molds. The assembly features a corrosion-resistant steel nozzle body and cover, independent thermocouple, 240-v a-c coil heater (120-v available) and leak-proof seal ring. All components are said to be readily replaceable, including a nickelplated beryllium/copper tip.

Thermocouple placement is said to improve heat profiles along the nozzle's entire length, while the overall design is intended to provide better thermal insulation. Gate-Mate 4 is available in seven lengths of 2-6 in. (CIRCLE 74)

Spear System (see above) is also offering new Multi-Tipped Spear Probes for microprecision molding of engineering resins. They are available with two, three, or four tips and can be bridged by a manifold for high-cavitation molds. (CIRCLE 75)

And Fast Heat Element Manufacturing Co., Elmhurst, Ill., has new Sensitwin multi-tip bushings able to gate up to eight parts, depending on diameter. They're for use both with Fast Heat's manifold systems and with direct nozzle gating. Integrally heated bushings come in three sizes with replaceable themocouples. (CIRCLE 123)

Multicavity molds with tight probe spacing is only one potential area of application of a new development from Osco, Inc., Rochester Hills, Mich. It has introduced an Adjustable Flow Nozzle System, in which each nozzle has a flow valve to allow the molder to make adjustments to create the most balanced fill pattern. Each nozzle's flow is infinitely adjustable from fully closed to fully opened position, via convenient adjusting knobs located outside the mold. Flow-control nozzles are available in three sizes with flow channels of 0.250-to 0.625-in. diam. All are available in any of the three most popular types of gating configurations. (CIRCLE 76)

Osco will also soon release a new product that is a marriage between its valve-gate and adjustable-flow systems. The Adjustable Flow/Valve Gate System is suited to multicavity molds with close center-to-center gate locations (1.5 in. minimum). It's said to provide zero gate vestige, with no drooling, no in-mold hydraulic plumbing, and fingertip control of cavity fill. (CIRCLE 77)

FOR CRITICAL COSMETICS

Mold-Masters, Ltd., Georgetown, Ontario, has introduced the Film Valve Gate Nozzle to improve upon conventional valve gates in providing cosmetically acceptable parts, especially for thin-wall applications. Company sources say the limitations of conventional valve gates include high heat and melt stress caused by high melt velocities passing through a small gate orifice. This reportedly can affect part strength and dimensional stability. The Film Valve Gate's relatively large-diameter valve effectively increases both the gate orifice and the cavity entry area. Since there is no flow bottleneck, the melt is guided smoothly from the nozzle into the cavity. The resulting shear velocities in the gate area are said to be extremely low, leading to reduced melt stress, and greater part strength and dimensional stability.

Filling speeds can be dramatically increased as well, leading to improved cycle times, according to Mold-Masters. And thin-walled parts reportedly are filled at lower injection pressures, which offer a major reduction in the machine tonnage required to clamp the mold. The Film Valve Gate is said to be mechanically reliable by design, because the valve is automatically opened or closed by cyclical injection pressures in the nozzle and cavity. Hydraulic or pneumatic pin-actuating pistons aren't required. (CIRCLE 78)

Melt Design, Inc., Lombard, Ill., has a brand-new modular system with a reportedly unique feature to provide optimum part cosmetics. This is a "floating needle" that conducts heat from the bushing down to the nozzle tip. "It always remains flush with the gate area, unaffected by thermal expansion," says sales engineer Panos Trakas, who developed the system. "This eliminates problems people have had with adjusting probe heights for thermal expansion, and provides the best gate mark," he adds. "It also means that we can double the gate size and maintain the same size witness mark, compared with a standard probe."

Modular, building-block design is also new with this latest series of components. Standardized modules--a trend in hot runners generally--reportedly minimize both design and machining costs. Modules are made of H13 tool steel, heat-treated and nitrided for added wear resistance. They have reduced body mass for quick warmup and an open-pipeline flow channel for processing materials with tight processing windows, says Trakas. Modules are individually heated and can be purged quickly for fast color charges, he notes. (CIRCLE 79)

In addition to new controllers (see above), Husky has introduced an axial-clamp heater that's said to reduce down-time by providing a faster and simpler method for assembling nozzle heaters. Heater bands can be removed from the front side of the manifold plate by loosening a single screw instead of two screws required for tangential clamps. The axial-clamp design reportedly is especially helpful where the nozzle heater bands are submerged into the manifold plate. Axial-clamp heater bands are offered with 149-w or 268-w ratings, as direct replacements for standard tangential-clamp heater bands, and are said to exhibit the same performance and heating characteristics. (CIRCLE 80)

Husky also has a new thermal gate design for PET preform molds as an alternative to its valve-gate systems. This approach reduces the gate mark to a smaller area for critical products. According to product manager Gordon Elliott, the thermal gate has resulted in simplification of mold construction, reduced maintenance, and improved gate appearance.

Husky's Test Facility, which has a 32-cavity preform system, was used to confirm the thermal gate's reliability and the molded product quality. The nozzle drop to each cavity has a screw-in tip for ease of cleaning or replacement while the mold is in the machine. Existing valve-gated molds can be converted to thermal gating. (CIRCLE 81)

Husky also is now making all of its mold plates and hot-runner manifolds from modified 420 stainless steel, replacing P20 and 4140 at no additional cost. The modified 420 stainless plates are prehardened to 28-34 Rc and provide improved corrosion resistance over 4140 and P20. Since electroless-nickel plating is no longer required, appearance and maintainability of the plates is improved. (CIRCLE 82)

PHOTO : Incoe's Thermal-Tip for its XRC bushings is designed to provide extra temperature control

PHOTO : at the gate, especially important when molding heat-sensitive engineering materials. It's

PHOTO : said to make it possible to raise or lower melt temperature just before it flows into the

PHOTO : mold.

PHOTO : Nissei ASB is offering Kona's hot-runner systems, like this "16-Up" type, on its new

PHOTO : stretch-blow machines and molds worldwide.

PHOTO : Mold Masters' Film Valve Gate Nozzle is aimed at improving upon conventional valve gates

PHOTO : in providing cosmetically acceptable thin-wall parts. Its large-diameter valve is said to

PHOTO : reduce melt stress, provide greater part strength and dimensional stability, and enable

PHOTO : filling speeds to be increased.

PHOTO : This new modular system from Melt Design features a "floating needle" that's said to

PHOTO : enable doubling of the gate size while maintaining the same size witness mark.

PHOTO : Husky's axial clamp heater bands are said to reduce downtime by providing a faster and

PHOTO : simpler method for the assembly of nozzle heaters. Bands can be removed from the front

PHOTO : side of the manifold plate by loosening a single screw instead of two screws required for

PHOTO : conventional tangential clamps.

PHOTO : Half of a 72-zone hot-runner control system, this cabinet contains 35 Barber-Colman's new

PHOTO : single-zone, amp FITT-8000 modules.