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 helix angle (H1) as the helical flight ; the longitudinal portion (A) further having a plurality of noncontinuous cross-cut grooves traversing at least one advancing groove ; and characterized by at least one of: at least one of the cross-cut grooves being oriented in the first threaded direction common to that of the helical flight and having a second helix angle (H2, H2', H2") greater than the first helix angle (H1) and less than ninety degrees; and at least another one of the cross-cut grooves oriented in a neutral direction parallel to the longitudinal axis (A1) and having a third helix angle (H3) of about ninety degrees. 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 helix angle (H1) as the helical flight ; the longitudinal portion (A) further having a plurality of noncontinuous cross-cut grooves traversing at least one advancing groove ; and characterized by at least one of: at least one of the cross-cut grooves being oriented in the first threaded direction common to that of the helical flight and having a second helix angle (H2, H2', H2") greater than the first helix angle (H1) and less than ninety degrees; and at least another one of the cross-cut grooves oriented in a neutral direction parallel to the longitudinal axis (A1) and having a third helix angle (H3) of about ninety degrees. <EOS>