A measuring apparatus of bulk viscosity includes a temperature-controlling cylinder having a test chamber for holding a molding material and at least one piston configured to seal an opening of the temperature-controlling cylinder. The temperature-controlling cylinder and the at least one piston are configured for measuring pressures, specific volumes and temperatures (PVT) of the molding material by applying a plurality of cooling rates to the molding material inside the testing chamber under an isobaric environment, or applying a plurality of mechanical pressures to the molding material inside the testing chamber under an isothermal environment. The measuring apparatus further includes a process module configured for deriving a plurality of parameters in relation to the pressures, specific volumes and temperatures (PVT) of the molding material based on the measurement; deriving an equilibrium pressure based on the plurality of parameters obtained from a first slowest cooling rate among the plurality of cooling rates.

The present disclosure provides a molding system for preparing molding articles. The molding system includes a molding machine; a mold disposed on the molding machine and having a mold cavity for being filled with a molding resin; a processing module configured to generate a mechanical pressure distribution of the molding resin in the mold cavity based on a molding condition for the molding machine, wherein the mechanical pressure distribution of the molding resin is generated based in part on a bulk viscosity effect of the molding resin; and a controller operably communicating with the processing module and configured to operate the molding machine for transferring the fluid molding material into the mold cavity with the molding condition using the generated pressure distribution of the molding resin to perform an actual molding process for preparing the molding article.

The present disclosure provides a method for deriving a bulk viscosity of a molding material. The method includes a step of deriving a plurality of parameters in relation to pressures, specific volumes and temperatures (PVT) of the molding material under a plurality of cooling rates and a plurality of mechanical pressures; deriving an equilibrium pressure based on the plurality of parameters obtained from a first slowest cooling rate among the plurality of cooling rates; deriving a rate of volume change of the molding material; and obtaining the bulk viscosity of the molding material based on the rate of volume change.

Systems and approaches for controlling a molding machine having a mold forming a mold cavity, a nozzle, and a screw that moves from a first position to a second position toward the nozzle and being controlled according to a mold cycle. Injecting a molten polymer into the mold cavity and obtaining a first measurement of a variable during the injection cycle using a first sensor positioned at or near the screw. A second sensor positioned at or near the nozzle is used to obtain a second measurement of the variable during the injection cycle. A measured compressibility ratio value is determined in the form of a difference between the measured variable obtained by the first sensor and the measured variable obtained by the second sensor. The measured compressibility ratio value is compared with a reference compressibility ratio value and at least one control parameter is adjusted based on a difference between the reference compressibility ratio value and the measured compressibility ratio value.