a plunger machine for molding reinforced polymer is provided . the plunger machine has particular application in molding polymer that is reinforced with particles having an aspect ratio greater than 1 : 1 . the plunger machine includes a barrel housing with a smooth barrel bore that defines a main melt chamber . a plunger housing , having a plunger bore , defines an initial melt chamber that is in communication with the main melt chamber . a plunger resides in the plunger bore and is reciprocatable therein . the barrel bore is continuously inwardly to provide a smooth transition and alignment of reinforcing members in the polymer mixture during the melt process . the smooth bore ensures substantial alignment of the reinforcement members with the longitudinal axis of the bore to avoid excessive breakage of the reinforcing particles and prepare the polymer mixture for extrusion into a mold assembly .