screwback

The period of screw rotation during injection molding when the plastic can flow into the mold.

Two main phenomena have been emphasized: (a) The transient nature of plastication during periods of screw rotation ("screwback") in comparison with the similar process in continuous extrusion. (b) The significant amount of melting produced by thermal conduction from the barrel while the screw is not turning.

But in the open (screwback) position, the plastic must progress through a series of labyrinths which produces a more turbulent flow.

A hook-shapped attachment for an earring that sits behind the earlobe and tightens with a screw. Also, an earring that uses this type of attachment.

The clip was a variation of the screwback; today, many persons who cannot wear pierced earrings choose clips as an option.

A mechanism for attaching a small item to clothing that operates by a post which goes through the cloth and a small backing plate that screws to the post. Also, the medal, tie pin, button, etc. that uses this type of attachment.

The quality of these buttons and charms is best rolled gold and hard enameled in correct colors, the button having either a screwback or a jewelers' catchpin.

The medal screwpost is placed through the uniform and retained by a circular screwback plate.

A type of case for a pocket watch where the mechanism is accessed by a removable back plate that screws onto the back of the case. Also, a watch that has such a case.

The watch stolen from Dan Payton had been an Elgin, with a screwback military case.

The effect of putting backspin on the cue ball.