Mold validation stages
Does the mold work? Activities during this phase relate to the validation of the injection mold’s mechanics.
The mold is mounted into the press and dry-cycled (no resin is injected) to ensure it opens and closes normally at operational temperature. The water temperature used is typically the mid-point of the chosen resin’s recommended range, and the temperature delta between the mold halves is set to zero. This facilitates basic operational checks for the ejection system, any mechanical movements/actions and shutoffs.
If the mold is functioning properly, the procedure continues, using the specified material. This allows checks for the proper function of the resin delivery system, manifold system and venting of the mold.
The part geometries of the mold can now be assessed with a basic inspection of the molded part for burns, shorts, flash, gate vestige, pin push, blemishes and more—basically any visual defects. If all goes well or once any problem areas have been identified and corrected, the process moves to phase 2.
Molding validation stages
Does the mold produce a good part? Executed properly, this phase begins the qualification process and becomes a scientific mold study “one validated step at a time,” per customer specifications.
While the sampling press may often be a different model and slightly different size (screw/barrel/clamp) than the projected production press, it can still be used to help define the eventual production process.
It is critical that each step is executed and documented individually in order to arrive at a best-practices scenario. Every element of the process (injection pressure, fill time, hold time, cooling) should be checked to determine its highest and lowest settings in order to make a part qualified to the customer’s performance and aesthetic requirements. A qualified part is one that falls within the range of all critical design tolerances, has the specified surface attributes, and maintains part integrity and stability during any functional tests, as determined by the customer.