Screwback

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.

Screwback time is a limiting factor when the plastication rate of the machine is too small or if the cooling time is small, as is the case with thin-walled mouldings.

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

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.

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

There he was three into the bunker and bogey for the hole was four, and making up his mind to lay the ball dead, he took his niblick and executed a beautiful screwback shot which landed within a foot of the pin, rolled to the edge of the hole, and there stopped dead, doubtless owing to the eternally damned influence of the aforesaid cloven hoofprint.