A screw for a plasticating apparatus, the screw comprising: a longitudinal axis (A1), the screw being rotatably supportable in a barrel for rotation about the longitudinal axis (A1), the screw having a core and at least one helical flight extending along a length of the screw , the helical flight extending in a first threaded direction and defining a first helical path having a first helix angle (H1) less than ninety degrees; the helical flight defining a helical channel ; and a longitudinal portion (A) of the screw having a plurality of advancing grooves with each advancing groove having at least one closed-end, the plurality of advancing grooves being arranged in a noncontinuous helix cut in the screw core in the helical channel of the screw , the plurality of advancing grooves forming a forward helical pathway in the helical channel for conveying material through the helical channel along the at least one helical flight , the advancing grooves being parallel to and having the same first helix angle (H1) as the helical flight ; characterized in that the longitudinal portion (A) further has a plurality of noncontinuous cross-cut grooves oriented in the first threaded direction common to that of the helical flight and/or in a neutral direction parallel to the longitudinal axis (A1) and traversing several of the plurality of advancing grooves ; and at least one of: (a) at least one of the plurality of advancing grooves having an advancing groove depth taper including an increasing depth taper or a decreasing depth taper; and (b) at least one of the plurality of cross-cut grooves having a cross-cut groove depth taper. a longitudinal axis (A1), the screw being rotatably supportable in a barrel for rotation about the longitudinal axis (A1), the screw having a core and at least one helical flight extending along a length of the screw , the helical flight extending in a first threaded direction and defining a first helical path having a first helix angle (H1) less than ninety degrees; the helical flight defining a helical channel ; and a longitudinal portion (A) of the screw having a plurality of advancing grooves with each advancing groove having at least one closed-end, the plurality of advancing grooves being arranged in a noncontinuous helix cut in the screw core in the helical channel of the screw , the plurality of advancing grooves forming a forward helical pathway in the helical channel for conveying material through the helical channel along the at least one helical flight , the advancing grooves being parallel to and having the same first helix angle (H1) as the helical flight ; characterized in that the longitudinal portion (A) further has a plurality of noncontinuous cross-cut grooves oriented in the first threaded direction common to that of the helical flight and/or in a neutral direction parallel to the longitudinal axis (A1) and traversing several of the plurality of advancing grooves ; and at least one of: (a) at least one of the plurality of advancing grooves having an advancing groove depth taper including an increasing depth taper or a decreasing depth taper; and (b) at least one of the plurality of cross-cut grooves having a cross-cut groove depth taper. (a) at least one of the plurality of advancing grooves having an advancing groove depth taper including an increasing depth taper or a decreasing depth taper; and (b) at least one of the plurality of cross-cut grooves having a cross-cut groove depth taper. <EOS>