INJECTION MOLDING: THE FUTURE IS NOW
T here's much that is new in allelectric machines, aimed at every segment of the market, from general- purpose to high-end. Not to be outdone, suppliers of hydraulic units continue to expand their ran...
There’s much that is new in allelectric machines, aimed at every segment of the market, from general- purpose to high-end. Not to be outdone, suppliers of hydraulic units continue to expand their range. Hybrids, too, are available in new designs ranging from essentially hydraulic machines having an electric screw drive to mostly electric machines that retain hydraulics for high-pressure clamping or high-speed injection. And this only scratches the surface.
Sumitomo has introduced the new high-speed double shot SEHS-CI Series of all-electric machines, featuring advancements made on the company’s SE-HS Series. Available in two model sizes, the SE230HS-CI (253 US tons) and the SE280HS-CI (308 US tons), the machines offer cycle-time enhancements such as 180 mold plate rotation in 0.8 seconds, mold open and close speeds of 1,300 mm per second (51.2 inches per second), and reduced cooling times through optimal four-circuit temperature control piping.
The units are available with a choice of injection units, screw diameters and screw types for shot sizes ranging from 2.9 to 10.7 ounces. “The SEHS-CI com- bines many of the advancements made in the high-speed SE-HS with double-shot capabilities and a new, faster rotating mold plate,” said Jeff Hicks, vice president, technical services for Sumitomo in North America. “Together with our SED-CI Series, we now have all-electric machines for double-shot applications from 83 to 308 tons.”
The Allrounder 570 A, the newest addition to Arburg’s Allrounder Series of allelectric injection molding machines, is not only the company’s largest model to date, with a clamping force of 2,000 kN, but also features a hybrid drive. In addition to the largest electric injection unit, size 800, a hydraulically actuated accumulator drive injection axis is available in conjunction with the size 1300 injection unit, permitting higher injection performance and injection speed, and making the model suitable for applications whose performance requirements exceed the capabilities of the size 800 unit. But the model still retains the energy efficiency of an allelectric unit, the company said, due to the other electric movement axes, for example on the clamping side.
Engel’s newest all-electric machine, the e-max, is designed to provide fast cycle times, precision and flexibility in a cost- effective package that fits a small industrial footprint. “The e-max is the all-electric solution for molders looking to reduce their plant energy costs while maintaining superior performance,” said Steve Braig, Engel North America president and CEO.
Available in sizes from 55 to 200 US tons, the e-max has a footprint of 13 feet by 4 feet for the 110 tonnage model, a 1.4 second dry cycle time, injection units with peak pressures of up to 40,6000 psi, and injection speeds up to 17.7 inches per second. The e-max units are particularly well suited for such applications as medical, consumer, and electronic components and automotive, Braig said.
Demag Plastics Group has extended its Ergotech Dragon Series of hydraulic machines at the top end of the line with its Ergotech Dragon 100 and Dragon 160 models. With these additions, the company is now offering a machine range featuring clamping forces from 500 up to 2,000 kN. The Dragon’s fully hydraulic clamp has been purpose-trimmed for high productivity. Key features include two clamp cylinders and a flow-volume multiplier on the inner side of the anchor platen. According to Demag, this design reduces the overall length of the machine while providing ample space for larger molds. The Dragon Series is also available with customized added functions, auxiliary devices and modifications tailored to specific applications.
New from Haitian is the Mars Series hydraulic machines, designed to offer substantial energy savings over competitive units. The machines combine a servomotor with a positive displacement gear pump, for delivery of the required flow and pressure as needed throughout the molding cycle. “The Mars Series provide almost the same energy efficiency as an all-electric, and between 20 and 80 per cent savings over a conventional hydraulic machine,” said Glenn Frohring, vice president of sales and marketing with Absolute Haitian.
“The advantage of this concept is the dramatic reduction of wasted energy associated with conventional hydraulic systems,” he continued. “During the pressure holding period, the rotational speed of the drive is significantly reduced. During cooling, the output from the drive system is zero and there is almost no energy cost at all.”
NEXT STEPS IN HYBRIDS
Toshiba Machine recently made available its new ED (Electric Direct-lock) Series hybrid machines, with models ranging from 650 to 3,000 metric tons. According to Toshiba, the units feature the newly developed hybrid direct-lock clamp, based on the hydraulic two-platen “DF” platform. The ED Series uses six high precision servomotors, plus synchronized hydraulic control; the servomotors provide the high speed clamp movement, while the hydraulic systems provide high clamp pressure and high pressure opening. The ED Series is designed to offer a small footprint, reduce oil requirements, and reduce mold maintenance, the company said.
Meanwhile, Nissei has developed the new X Series of hybrid machines, which the company claims offer energy savings of approximately 30 per cent over comparable hydraulic models. Available in sizes ranging from 40 tons to 460 tons, the units offer ramp-up times of 40 to 50 ms, which represents a high response on par with all-electric machines. The injection speed can be controlled over a wide range, from 1 mm per second to a maximum of 300 mm per second, the company said. Additionally, the X Series units are capable of sustaining high injection holding pressure longer than comparable all-electric machines, while using a maximum of 56 per cent less hydraulic oil than hydraulic models.
NEW SYSTEMS, MERGERS & CONCEPTS
Husky Injection Molding Systems has introduced a system designed to improve cost-effectiveness and productivity for molders. The company’s HyPET 90 is a PET system featuring Flex Mold, a modular low cavitation PET preform mold intended for customers who use the same machine for multiple applications, and therefore need to change molds with minimal downtime — particularly converters producing smaller volumes of preforms. With Flex Mold, the bodies of the cavities can be changed while the gate pad remains in the mold. The design of the mold eliminates the need to cool down and reheat the hot runner during a part changeover, the company said, reducing mold change times by as much as 75 per cent compared to a conventional mold.
Milacron has expanded its Servtek TCS barrel heating and cooling technology for injection molding machines, a move designed to save energy and improve processing. According to Milacron, the Servtek TCS injection unit barrel heater provides a high radiant energy release from an element that directs 100 per cent of the heat directly into the barrel. The encap- sulated barrel keeps all the heat inside, allowing a fast heat-up cycle. “The technology is simple and easy to use, and is quite different from old-fashioned ceramic heater bands, insulated heater bands and water-cooled systems that all must heat themselves up prior to delivering heat to the barrel,” said Rich Waterfield, Servtek product manager. “Presently, the heater bands are suitable for all machines except those with a barrel smaller in diameter than 5.75 inches.”
Following the purchase of Battenfeld by auxiliary supplier The Wittmann Group, the companies are working to integrate services. “Our goal is to complete and commercialize the integration by the end of 2008,” said Michael Wecker, CEO of Battenfeld of America. When finished, the integration will offer substantial benefits for injection molders, he said. “Traditionall
y, resin and finished product handling has been carried out separate from the machine molding process, and completely separate from the supplier aspect,” he explained. “We can now offer a seamless, one-stop shop, and this provides several advantages.”
Of particular importance, Wecker continued, is the linking of the injection molding machine with the automation through a complete integrated control panel. “Until now, a plastics processor employed a machine company to set up one controller, and an auxiliary supplier to set up another, and typically the two were not communicating efficiently,” he said. “Ultimately, we’ll be able to offer an entire system on one synergized, unified control panel.”
Krauss Maffei, meanwhile, has developed a new concept that cuts cycle times in the production of molded parts with integrated vibration damping, by linking injection molding with extrusion and reaction processing in a single manufacturing cell.
The process teams a Krauss Maffei injection molding compounder (IMC) with the company’s CX injection molding machine to produce 2C parts. With a crosslinking stage, the process delivers a product with the elasticity and resilience of natural rubber and other elastomers, with a cycle time of approximately 60 seconds. The crosslinking agent is added to the melt as a liquid polymer, the company said, and then mixed on the injection molding compounder, which yokes continuous extrusion and discontinuous injection in one machine. Because the extruder operates continuously, it ensures that the crosslinking agent is metered evenly into the melt and thoroughly mixed to produce a homogenous compound. The plasticized and homogenized material is injected via a heated runner and an injection piston into the mold.
Boy recently introduced the Procan ALPHA control, for injection molding machines with clamping forces below 1,000 kN. With a 15-inch full touchscreen system powered by a patented rapid UTX PC hardware system, the control is designed to save time through effective processing of analogous signals. It reacts without delay and frees the PC from all time-critical tasks, the company said. The system also features the Iterative Learning Controller (ILC), designed to achieve actual values in a stable state. According to Boy, advantages of the ILC include the reduction of start-up and set-up times, and control of deviations common to continuous operation. Additionally, the profiles of actual and set values are largely approximated, thereby minimizing frequency peaks.