Injection molding system and injection molding method

An injection molding method, comprising:

• providing an extruding system configured to produce a mixture of a polymeric material and a blowing agent, a first discharging channel communicable with the extruding system and including a first outlet disposed distal to the extruding system;
• providing a molding device, wherein the molding device includes a first mold cavity and a second mold cavity separated from the first mold cavity, a first feeding port in communication with the first mold cavity, and a second feeding port in communication with the second mold cavity, wherein the first outlet is engageable with the first feeding port and the second feeding port respectively;
• 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;
• 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,
• injecting a first amount of the mixture into the first mold cavity having the first predetermined pressure through the first feeding port;
• injecting a second amount of the mixture into the second mold cavity having the second predetermined pressure through the second feeding port;
• foaming the first amount of the mixture in the first mold cavity;
• foaming the second amount of the mixture in the second mold cavity;
• discharging at least a portion of the first gas from the first mold cavity during or after the foaming of the first amount of the mixture in the first mold cavity until the first mold cavity is sensed to have a third predetermined pressure;
• and
• discharging at least a portion of the second gas from the second mold cavity during or after the foaming of the second amount of the mixture in the second mold cavity until the second mold cavity is sensed to have a fourth predetermined pressure,
• wherein the first predetermined pressure is different from the second predetermined pressure, and the third predetermined pressure is different from the fourth predetermined pressure.