Innovation | hotrunners
Autodesk’s Moldflow product; Synventive is working with a number of simulation specialists to integrate technologies such as synFlow. Italian hotrunner manufactuer HRSflow has also
expanded its sequential moulding product options with the introduction of FlexFlow, an electrically powered valve gate actuation system allowing fully independent control of each gate during mould filling. Intended for large part applications such as automotive bumpers, door panels, instrument panels and high quality optical production, the FlexFlow system also provides control of the position, acceleration, speed and stroke of each individual valve pin so that filling and packing profiles can be optimised.
By eliminating the ‘pressure jump’ when each gate is opened, the company claims it is possible to eliminate flow marks on the part, adjust the position of weld lines, and eliminate flashing at the injection point. It is said to be particularly useful where glass reinforced polymers are being processed with a complex sequen- tial filling pattern. The FlexFlow electric cylinder is designed for use
with the company’s M, G and A series hotrunners (with diameters of 5, 7 and 10mm) at pressures up to 2,000 bar. The cylinder uses a side placement layout, which reduces the overall height, and is the same size as the company’s standard hydraulic side-layout actuation devices. It is designed for use with the FlexFlow controller, which offers valve pin positional accuracy to within 0.01mm and is available in 8, 12 and 16 zone con- figurations.
Manifold developments Canadian hotrunner systems supplier Mold Hotrunner Solutions (MHS) has earned a reputation for delivering innovative solutions to difficult moulding challenges and its latest development – the Rheo-Pro Slide manifold system – demonstrates that well. Rather than the usual fixed manifold construction, the Rheo-Pro Slide manifold is assembled with rotary melt transfer joints that allow individual segments to move freely within moving tooling elements such as sliding cores or lifters. According to MHS founder and
president Harald Schmidt, this allows the polymer to be distributed anywhere within the mould without interrupt- ing the polymer flow, enabling tool designers to overcome one of the
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biggest obstacles when trying to implement a hotrunner feed system in parts with complex external side feature undercuts, such as ribbing. The system is also expected to find applications in design of stack, tandem and rotating element or cube moulds. The technology has
already been applied to produce a mould for production of a large thin wall PP storage container measuring 1.5m by 1.5m by 1.0m. Each wall measures just 1mm thick and carries extensive reinforcing ribs to provide the required rigidity.
Schmidt says similar parts would, in the
past, have been manufactured using thermo- forming technology. However, the company developed a solution around its Slide manifold and Rheo-Pro valve gates that enabled production using a sequential filling injection moulding process. The manifold is a five-ele- ment design equipped with 94 valve-gates arranged in 49 injection control zones. Like all MHS valve gate systems, the valve pins are
actuated by compressed air and controlled using the company’s Rheo-Pro CV-ST sequence/temperature controller. “We prefer to use air because it is always available, it can take high temperatures and there are no cables,” says Schmidt.
Control improvements US-headquarted Gammaflux has
extended its premium hotrunner controller product line with the introduc- tion of the G24 in a 12-zone variant. According to the company, the new addition makes the performance and many of the high end features of its larger controllers available to moulders running small hot runner systems. “We are leveraging a global supply
chain to offer high performance at a much lower cost,” says Gammaflux director of market development Mike Brostedt. Savings have been made through the use of a half-size enclosure and the adoption of the Windows CE operating system, which carries a lower licensing charge. The company has also benefited from the falling prices of 8-inch touchscreens. Brostedt says the new system cuts
Left: Mold Hotrunner Solutions used its Rheo-Pro Slide manifold technology in this 94-gate, 49-zonehot runner for production of a large, ribbed thin wall storage container
Above: The FlexFlow
electric valve gate actuator
from HRSflow fits in the same space as hydraulic side-layout alternatives
November/December 2013 | INJECTION WORLD 53
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