Three-dimensional suction molding method for polymeric foams

A 3D suction molding method comprising:

• conveying polymeric material in a downstream direction in an extruder including a screw configured to rotate in a barrel during a plastication period of a suction molding cycle;
• introducing blowing agent into the polymeric material to form a mixture of polymeric material and blowing agent in the extruder, wherein the blowing agent is introduced into the polymeric material during only a portion of the plastication period;
• accumulating a shot of the mixture in an accumulation volume;
• moving a piston to inject the shot through an outlet to form a parison in a cavity defined between walls of a 3D mold;
• applying a vacuum to pull the parison through the mold cavity;
• blowing the parison out against the walls of the mold;
• and
• opening the mold to recover a 3D suction molded polymeric foam article.