fitted with a foaming agent inlet the barrel had an internal diameter of about 2 inches the plunger had a metering section length of 1 25 inches a primary mixing section length of 3 9 inches and a combined valve section and end section length of 1 85 inches grooves in the metering and mixing section were 0 25 inches deep the low lands in the mixing section provided a clearance of 0 025 inches with the barrel wall and the high lands a clearance of 0 002 inches the plunger rotational speed used was 100 rpm the resin was a thermoplastic polyester with a melt flow viscosity index of about 2 to 3 the plasticate was processed at a temperature of about 410 u00b0 f and a throughput rate of 14 3 pounds per hour in the molding cycle sequence the mold gate opened for 20 seconds and closed for 90 seconds during the gate open interval the plunger stroked forward ramming a plasticate charge of 7 fluid ounces into the mold during the gate closed interval the mold cooled opened discharged the solidified article and closed concurrently during the gate closed interval the plunger moved rearward in its barrel as a new charge of plasticate accumulated ahead of it the foaming agent employed was nitrogen gas supplied from a high pressure cylinder initially at a pressure of about 2400 psig the nitrogen pressure.