A method of determining a target value of a state variable includes preparing a mixture of the molding material and the gas with different test values of the state variable, and the mixture is respectively compressed or decompressed. In the compression or decompression step, the state variable of the mixture and/or a further state variable of the mixture is measured directly or indirectly, and determination values of a compression behavior variable characteristic of the compression behavior of the mixture are determined from the measurement values. A criterion directed to a solution state of the gas is checked, and a lowest or highest value of the state variable is deduced at which the gas is in solution in the molding material. The lowest or highest value of the state variable at which the gas is in solution in the molding material is used as the target value.

A method of determining a solution state of a gas in a plastic melt used in a plastic shaping method includes: (vi) providing the plastic melt together with the gas in a chamber, (vii) altering—in particular reducing—a volume of the chamber to alter a pressure of the plastic melt together with the gas—in particular increased from a first pressure value to a second pressure value, (viii) introducing the plastic melt into a shaping cavity, (ix) computing at least one compression parameter characteristic of the compression behaviour of the plastic melt, in particular a modulus of compression, from the first pressure value and the second pressure value, and (x) determining from the at least one compression parameter whether the gas is substantially completely dissolved in the plastic melt and/or a solubility limit of the gas in the plastic melt is determined from the at least one compression parameter.

A controller for an injection molding system is in communication with a melt flow control unit, a gas assist control unit, and a gas counter pressure control unit. The controller can effect real-time adjustments to gas assist pressure and/or gas counter pressure as a function of melt pressure or flow front position.

A method of determining a target value of a state variable includes preparing a mixture of the molding material and the gas with different test values of the state variable, and the mixture is respectively compressed or decompressed. In the compression or decompression step, the state variable of the mixture and/or a further state variable of the mixture is measured directly or indirectly, and determination values of a compression behavior variable characteristic of the compression behavior of the mixture are determined from the measurement values. A criterion directed to a solution state of the gas is checked, and a lowest or highest value of the state variable is deduced at which the gas is in solution in the molding material. The lowest or highest value of the state variable at which the gas is in solution in the molding material is used as the target value.

An injection molding apparatus including an injection device, a mold, a gas supply device, and a temperature control device is provided. The mold has a mold cavity, wherein the injection device is adapted to inject a material into the mold cavity. The gas supply device is adapted to supply a gas to the mold cavity such that the pressure in the mold cavity is increased. The temperature control device is adapted to control the temperature in the mold cavity. In addition, an injection molding method is also provided.

A controller for an injection molding system is in communication with a melt flow control unit, a gas assist control unit, and a gas counter pressure control unit. The controller can effect real-time adjustments to gas assist pressure and/or gas counter pressure as a function of melt pressure or flow front position.

A method of determining a solution state of a gas in a plastic melt used in a plastic shaping method includes: (vi) providing the plastic melt together with the gas in a chamber, (vii) alteringin particular reducinga volume of the chamber to alter a pressure of the plastic melt together with the gasin particular increased from a first pressure value to a second pressure value, (viii) introducing the plastic melt into a shaping cavity, (ix) computing at least one compression parameter characteristic of the compression behaviour of the plastic melt, in particular a modulus of compression, from the first pressure value and the second pressure value, and (x) determining from the at least one compression parameter whether the gas is substantially completely dissolved in the plastic melt and/or a solubility limit of the gas in the plastic melt is determined from the at least one compression parameter.

An injection molding system includes an extruding system, a discharging channel, a molding device including a first and second mold cavities, and a pressure regulating system regulates pressures inside the first and second mold cavities. An injection molding method includes providing a molding device having a first and second mold cavities, a first feeding port in communication with the first mold cavity, and a second feeding port in communication with the second mold cavity; sensing a first pressure in the first mold cavity, and injecting a first gas into the first mold cavity until the first mold cavity is sensed to have a first predetermined pressure; and sensing a second pressure in the second mold cavity, and injecting a second gas into the second mold cavity until the second mold cavity is sensed to have a second predetermined pressure, wherein the first and second predetermined pressures are different.

A controller for an injection molding system is in communication with a melt flow control unit, a gas assist control unit, and a gas counter pressure control unit. The controller can effect real-time adjustments to gas assist pressure and/or gas counter pressure as a function of melt pressure or flow front position.

An injection molding system includes an extruding system, a discharging channel, a molding device including a first and second mold cavities, and a pressure regulating system regulates pressures inside the first and second mold cavities. An injection molding method includes providing a molding device having a first and second mold cavities, a first feeding port in communication with the first mold cavity, and a second feeding port in communication with the second mold cavity; sensing a first pressure in the first mold cavity, and injecting a first gas into the first mold cavity until the first mold cavity is sensed to have a first predetermined pressure; and sensing a second pressure in the second mold cavity, and injecting a second gas into the second mold cavity until the second mold cavity is sensed to have a second predetermined pressure, wherein the first and second predetermined pressures are different.