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While hot runner systems have proven their worth over the years in terms of increased productivity and material savings, it’s a tough market out there. Still, most are investing in R&D to provide specialty products for new applications, and promoting the value of hot runner systems, as was evident at NPE.

Clare Goldsberry

July 30, 2009

8 Min Read
Mature products, slow moldmaking environment keep hot runner suppliers innovating

While hot runner systems have proven their worth over the years in terms of increased productivity and material savings, it’s a tough market out there. Still, most are investing in R&D to provide specialty products for new applications, and promoting the value of hot runner systems, as was evident at NPE.

It’s a mature market out there for hot runner systems, especially in Europe and the United States, say some in the industry, and that makes for a tougher sales environment. Many in that business say rather than technological innovations, they’re coming up with “tweaks” and “value propositions” such as systems designed to serve specific markets or products.

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Mold-Masters’ Sprint hot runner system is engineered for ultrafast beverage closure molding.

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Incoe’s Quick-Flo system is shown here for a 64-cavity, high-speed mold.

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Husky offers more than 100 Pronto hot runner manifold layouts, which the company says provide increased flexibility of plate sizes and pitch spacing.

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An eight-drop Pronto system features an Ultra 500 hot tip.

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D-M-E introduced its Eco-Smart hot runner system at K 2007 to run biopolymers such as PLA for packaging applications.

An example of these specifically designed systems is Mold-Masters’ Purpose-Built products, introduced at NPE2009. These hot runner systems are built to address specific customer needs in the closure, medical, multimaterial, and PET markets. Purpose-built products have been engineered to provide rapid color change and fill balance, fast molding cycles, tight pitches, low energy consumption, and high levels of reliability.

“It’s clear to us that the generic hot runner solution does not address the specific needs of today’s sophisticated moldmakers, molders, and OEMs,” says Jonathan Fischer, CEO of Mold-Masters. “These stakeholders have realized that to sustain profitability, they must specialize in niche applications and utilize the very best technology and suppliers to outperform their competition.”

One of the new products Mold-Masters launched at NPE is the Sprint hot runner system engineered specifically for ultrafast (cycles between 3 and 6 seconds) beverage closure molding. The Sprint system uses a unique nozzle tip design coupled with Mold-Masters manifold technologies to provide significant performance benefits for beverage closure molders. According to Mold-Masters, the Sprint systems have 10% lower pressure drops, greater than 90% fill balance, and 25% faster color changes than comparable systems, allowing molders to reduce part weights and bring molding costs down to new thresholds.

Finding the right pockets of business

Although the plastics industry has come to accept hot runner systems as a way to improve production and reduce costs, the economy hasn’t done the industry any favors, says John Blundy, VP business development for Incoe Corp. Still, the company has developed new products to keep molders on the cutting edge. “When business is like it is, there are really only two positions to take,” he says. “You can hunker down and try to ride out the storm, or get aggressive. We’re taking the position of being aggressive. There are good pockets of business. One of the new products we’ve introduced at NPE is a hot runner line to augment our lines in new markets. There’s no one-size-fits-all, and Incoe is poised to focus on and participate in the areas of activity.”

One of the company’s new hot runner systems, Quick-Flo (QF), is designed for the processing of commodity-grade resins used in high-cavitation molds, and is in addition to the Direct-Flo (DF) Gold, which is ideal for technical part molding up to 1000g shot weights per nozzle. “The DF has been a mainstay for Incoe in the automotive, appliance, gears, and lens markets, so now we’re introducing it for packaging and medical applications,” Blundy said at NPE.

QF systems are used for caps/closures, medical disposables, pharmaceutical, and packaging applications, which demand maximum output, repeatable part quality, and superior cosmetics. Nozzles are available with flow channel diameters of 3, 5, and 8 mm and shot sizes of 3-375g. Gating options include thermal tip and valve gate.

QF also uses Incoe’s new nozzles with twin-heater technology for fail-safe operation. And QF systems that use Opti-Flo manifolds with Beaumont Technologies’ MeltFlipper technology can provide improved cycle times and processing capability, Blundy explained.

Adding value

Some hot runner suppliers are looking for ways to give their users more capabilities within existing product lines. Starting from the standpoint that a hot runner control alone is not able to detect the sensitivity of the individual nozzles because it faces a closed loop control, Priamus System Technologies added a hot runner balancing tool to its Priamus Fill hot runner control system. This tool determines automatically the sensitivity of each nozzle. Temperature sensors placed in the cavity check how the flow behavior of the melt changes when the individual nozzle temperatures have changed by a certain value.

Husky Injection Molding Systems expanded its Pronto line of hot runners to include 350, 500, 750, and 1000 models, adding the 350 model for throughputs of less than 50 g/sec. All versions offer flexible plate sizes and interface position, with both hot tips and valve gates. Husky’s Pronto program offers customized hot runners and simple integration for the cost of a standard hot runner. The system can be tailored for each customer’s specific application.

Commenting on Husky’s Pronto hot runner technology, John Galt, president and CEO, says that one of the advantages is minimizing stress on the tool and reducing mold wear, particularly when running fast cycles. Husky’s theme for NPE2009, “It All Starts With the Part,” stressed moving beyond the mold and looking at the part’s requirements, monitoring all critical variables and identifying problems before they occur. “It’s part of the whole life cycle cost,” says Galt. “It includes design, mechanical engineering, process parameters, and optimizing setup to minimize stress on the mold components.”

Running faster

A significant component of a part’s cost is cycle time, and using runnerless molds is one key to reducing it. But there are other considerations to reducing cycle times as well. Osco Inc. recently introduced a new Machine Shut Off (MSO) nozzle that improves cycle times through quicker recovery and eliminates drooling caused by backpressure.

“Faster cycle time ensures immediate screw recovery after injection,” says Osco’s Peter Rebholz. “The MSO positively shuts off the machine nozzle orifice, and this enhances productivity and profitability while eliminating waste.”

Each MSO is available with either pneumatic (air) or hydraulic-drive cylinders. Two standard-size cylinders are available: 7.14 inches for air and 5.55 inches for hydraulic. Standard Series 200 and 400 offer a variety of tip designs, valve pin and feed channel circumferences, and lengths that will adapt to any application. The MSO is also field serviceable, so repairs and adjustments can be made onsite and with minimal downtime.

Osco also came out with its new Recessed Gate Tip (RGT) with 11 different gate diameter size options (0.040-0.150 inch) that eliminate secondary setup operations required to install the nozzle and set up the cavity for machining of the tip. “The gate mark is below the surface, resulting in a cleaner, more accurate finish,” says Rebholz. “The RGT optimizes gate land and gate needle relationships, and it is available with any full body tip.”

Either full-tip or half-tip radius versions give molders the versatility they need to handle any application. Tall gate vestige and/or shearing of the resin associated with an improper relationship between the gate needle and gate land are now a thing of the past, explains Rebholz. Downtime and expenses are minimized or totally eliminated.

Running biomaterials

Of course, hot runner products have to adapt to more than just a mature market and a contracted economy. The expansion of molders processing bioresins, which requires some technical finesse primarily because of their low melt temperatures, has placed demands on runnerless molding systems. While not new to the market, D-M-E’s Eco-Smart hot runner system is designed specifically for biopolymers such as polylactic acid (PLA) to address new packaging requirements. A beta version of Eco-Smart was first introduced to the market at K 2007, and since then D-M-E has improved it for increased performance, which the company showcased at NPE2009. Eco-Smart’s application-engineered hot runner nozzle assemblies feature corrosion-resistant components and address the low pressure requirements and cooling issues that PLA users face.

With the bioresin marketplace constantly changing, D-M-E has worked with its material partners on extensive testing in real-world conditions to ensure Eco-Smart is optimized for the latest materials and technologies. The system features an uninterrupted material flow path and a thermal isolation component design, both of which minimize shear. To promote easy maintenance, Eco-Smart manifolds and nozzles are heated inside and out and have front-removable heaters, thermocouples, and nozzle tips.

“The introduction of new biodegradable resins and bio-based resins will continue to grow as landfills reach capacity and oil prices rise,” said D-M-E’s president Bob McKee. “D-M-E is committed to being an essential resource to our customers who adopt these eco-friendly resins.”

Why valve gating?

Harald Schmidt, president of Mold Hotrunner Solutions, says that the main advantage of hot runner valve gating is its consistency from cavity to cavity and from shot to shot. “Valve gates offer more processing control than traditional thermal gates using hot-tip nozzles because small changes in the processing parameters and fluctuations of the melt viscosity do not affect their performance,” he says. MHS offers multitip nozzles, hot runner systems for high-cavity molds, custom engineered tips, and its Rheo-Pro system for the production of medical parts. [email protected]

About the Author(s)

Clare Goldsberry

Until she retired in September 2021, Clare Goldsberry reported on the plastics industry for more than 30 years. In addition to the 10,000+ articles she has written, by her own estimation, she is the author of several books, including The Business of Injection Molding: How to succeed as a custom molder and Purchasing Injection Molds: A buyers guide. Goldsberry is a member of the Plastics Pioneers Association. She reflected on her long career in "Time to Say Good-Bye."

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