Method for removing bubbles from a molten substrate. The molten substrate from a furnace passes through a downtube to reach additional manufacturing tools, such as an extrusion bushing. One or more ultrasonic sensors are arranged along the downtube. The ultrasonic sensor(s) transmit ultrasonic energy into the molten substrate and measure a characteristic of the ultrasonic energy, such as a propagation time for the ultrasonic energy to be reflected back to the ultrasonic sensor(s). A bubble is detected when a change in the Characteristic of the ultrasonic energy is detected. When a bubble is detected, flow through the downtube is diverted to a duct to remove a slug of molten substrate that includes the bubble.

Systems for manufacturing bulked continuous carpet filament from polymer, where the systems are configured for: (1) passing polymer flakes through a crystalliers; (2) melting the polymer to create a first single stream of polymer melt; (3) separating the first single stream of polymer melt into multiple streams of polymer melt; (4) exposing the multiple streams of polymer melt to a pressure of between about 0 millibars and about 25 millibars in a chamber; (5) recombining the multiple streams of polymer melt into a second single stream of polymer melt; and (6) providing the second single stream of polymer melt to one or more spinning machines that are configured to form the second single stream of polymer melt into bulked continuous carpet filament.

A signal acquisition unit of an abnormality detection device for a twin-screw extrusion molding machine, when the twin-screw extrusion molding machine that melts and kneads a fed resin raw material is in operation, acquires an AE output of an AE sensor installed on a surface of a housing of the twin-screw extrusion molding machine. A determination unit determines whether an abnormality occurs in the twin-screw extrusion molding machine, based on a relationship between the AE output and a first threshold and a second threshold.

A cooling apparatus for an extruder includes a supply line configured to receive bulk coolant from a supply circuit via an inlet. The supply line delivers supply coolant to the extruder along a flow path. A return line communicates expelled coolant from the extruder, and a circulation line connects the supply line to the return line. The circulation line supplies a recirculated portion of the expelled coolant to the supply line and mixes the bulk coolant with the recirculated portion of the expelled coolant forming the supply coolant. A bypass line connects the supply line to the return line, and a flow control valve connects one of the supply line and the return line to the bypass line. A proportion of the expelled coolant to the bulk coolant forming the supply coolant is adjusted by the flow control valve to control the temperature of the supply coolant.