Innovation | hotrunners
The use of Synventive’s synFlow technology eliminated the surface blemishes on this seat back produced by Boshoku for Audi (as can be seen in the right image)
The synFlow system applies the same principles of
valve pin control to hydraulically-activated systems. In use in a number of European development sites for more than a year, the technology is now being rolled out globally, providing closed loop positional, velocity and acceleration control of the valve gate pin. It is particu- larly suited to applications such as sequential valve gate systems for production of large area parts with long flow lengths such as bumpers and instrument panels. The synFlow controller allows the initial opening speed of the valve pin to be kept low to prevent an explosive rush of pressurised plastic into the mould. Then once the initial fill has commenced the pin can be opened for the remainder of its stroke at maximum speed to rapidly fill the part. This two-speed process is claimed to provide a smoother fill and reduced hesita- tion. It is said to overcome common defects such as pressure alteration, opposite direct gating and sinking. One of the early European users of the system is Boshoku Automotive Europe, a Tier One supplier to BMW, VW and Daimler. It was experiencing surface gloss variation on seat back covers it was producing for Audi in a PP compound containing 15% TPV due to sudden changes in the velocity of the melt flow-front. Adopting the synFlow technology in the two-cavity mould allowed the 800g parts to be moulded without surface issues. A six-drop manifold system was used in this case with two nozzles feeding onto cold runners and four synFlow valve gates feeding direct into the moulding. Moss says the company is now trialling a new
technology that will extend this flow control capability to pneumatically-actuated valve pins. The nuGate system uses a sensor in the pneumatic actuator to provide closed loop control of position and velocity and is more compact than the eGate and synFlow units. “We are working with a couple of customers and expect to roll this out in Q1 of next year. The initial market will be Asia
www.injectionworld.com November/December 2013 | INJECTION WORLD 51
as it is more suited to the electronics industry-sized moulds,” he says.
Selling these ‘enabling’ process technologies is a
challenging task, says Moss, as customers often don’t realise that they need the improved melt control until they have a production problem on their hands. One key tool in marketing flow control techniques is the ability for the customer to simulate them. “When they can do that they can see the benefits more directly,” Moss explains. Direct Feed can already be simulated within
Before (top) and after images show how HRSflow’s FlexFlow electric valve gate system has allowed hesitation marks to be eliminated in this automotive component
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