B - Polymer Processing Glossary of Terms
Back draft - A slight undercut or tapered area in a mold tending to prevent removal of the molded part. Back plate - A plate used as a support for the cavity blocks, guide pins, bushing, etc. Sometimes called support plate. Back pressure - Pressure exerted by the injection unit's cylinder against the screw as it recovers or plasticates. Used to increase the melt homogeneity. Increases melt temperature. Baffle - A plug or other device inserted in a flow channel to divert cooling medium to a desired path. Balanced runner - A runner system designed to place all cavities at the same distance from the sprue. Ball check valve - An anti-back flow valve which prevents the plastic melt from flowing back over the screw during injection. Band heaters - Electrical heaters surrounding the barrel and nozzle of the injection unit. Bar chart - Histogram Barrel (extruder) - Hollow tube in which plastic is gradually heated and melted. Inside the barrel is a helical screw which compresses an...