| 摘要 |
An improved extrusion-based manufacturing system includes one or more extruders, with each extruder containing at least two stages of increasing pressurization. In a preferred embodiment, a first stage of pressurization is created by the motion of a solid wafer of thermoplastic through an orifice into a heater chamber. In another preferred embodiment, the wafers are stored in removable, electronically tagged, cassettes and are removed therefrom by a stapler mechanism which feeds the wafers from the cassette to a tractor feed mechanism on demand. In each embodiment, a second stage of pressurization is provided by a pump, with the first stage pressurization maintaining a flow of thermoplastic to the pump under all expected pump rates.
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