FLAT SYSTEM AND NON-TURBULENT FLOW PIN POINT TIP NEW CONCEPTS

摘要

The Flat gating system evolved from a controlled study of gate size optimization when applying Hot Runner pinpoint gating techniques. A major objective of the study was to maximize gate cosmetics when applying these gating techniques to a variety of plastic resins, each with their own distinct characteristics. The size of the gate was determined by the type of plastic resin used. A flat diameter was established at the downstream end of a pinpoint gating tip. The size of the flat was determined by the volume of resin required to fill the part. The results of the study produced a technique that allows for the calculation of specific gate sizes. The technique can be used to achieve a minimal gate vestige while maintaining optimum flow performance. The Flat System technique is independent from tip design geometry, and can be used with most resins (filled or unfilled) without regard for material viscosity. A second study was initiated to determine the direct wear characteristics (shear effect) of pinpoint tips when processing plastic resins with abrasive fillers. In recent years, the industry has used harder steel alloys (carbide) for tip construction in an effort to combat tip erosion (wear). The second study resulted in a new "Non-Turbulent" design that maintains laminar flow along the pinpoint tip. The new design minimizes shear that is produced by "turbulence," rather than trying to resist it. This allows for tips made of softer steel alloys with increased life expectancy. Applying these new concepts to pinpoint tip construction results in improved molded part quality, improved gate cosmetics and reduced tip maintenance requirements.