Hot Runners (September 01, 2009)
Valve gates for micro parts
September 1, 2009 by Canadian Plastics
Mold Hotrunner Solutions Inc. introduces a new Rheo-Pro multi-tip valve gate hot runner, designed for molding direct gated micro parts with crisp, clean gate marks.
The M05VG can direct valve gate micro parts with a weight of less than five mg. It delivers crisp, clean gate marks of 0.7-mm to 1.0-mm diameter with zero gate vestiges. Traditional thermal gating and hot tip gating experience inherent problems with micro parts because of cold slugs below the surface and gate vestige on the surface. These methods often fail to achieve the part quality required for precision micro parts, particularly in medical applications.
Precision shut off pins guarantee the ultimate gate control. The valve actuators are synchronized with millisecond accuracy throughout all gates to deliver a completely balanced melt flow. The M05VG nozzle is especially suited for commodity materials, but performs well with engineering and high temperature polymers.
Mold Hotrunner Solutions Inc. (Georgetown, Ont.);
RJG‘s new Balance Viewer software provides a tool for users to visually balance hot runner manifolds.
Most molders try to adjust the balance by running a series of fill-only parts and adjusting the tip temperatures until the parts are about the same size or weight. With an eDart process controller and cavity pressure or cavity temperature sensors in every cavity of a mold, you can use the data to balance the tip temperatures. The eDart computes cavity fill times that directly reflect the fill imbalance. This optional software tool uses the data to make the visual process of balancing much simpler. You look at the high or fast filling cavities and lower those temperatures while raising the tip temperatures for the lower bars until they all come into balance.
Selection buttons on the software allow you to check the balance of other parts of the process: filling and packing, pressurization and mold temperature. If the mold has only temperature sensors (no pressure) you can see the balance of the time to reach the sensor and the mold temperature at that point. The viewer tool automatically sets up and scales the bars for the number and range of sensors found. Once a tool is balanced any odd behavior, such as material build-up or clogging, can initiate a warning system and will not be masked by automatic control adjustments.
RJG Inc. (Traverse City, Mich.); www.rjginc.com; 231-947-3111
Dier International Plastics Inc. (Unionville, Ont.); 905-474-9874
KLA Enterprises (Kitchener, Ont.); 519-894-0164