SCREW DESIGNS FOR USE WHEN MOLDING PRODUCTS THAT INCLUDE SHEER SENSITIVE MATERIALS

1 . A system for molding products that include long fiber thermoplastic materials, the system comprising:

a barrel;

a hopper in communication with the barrel;

a screw disposed within the barrel, the screw being designed to rotate and reciprocate within the barrel;

wherein the screw includes a metering section; and

a plurality of dome members coupled to the screw and disposed along the metering section.

2 . The system of claim 1 , wherein the screw includes a root and a helical thread disposed about the root.

3 . The system of claim 2 , wherein at least some of the plurality of dome members are disposed between adjacent windings of the helical thread.

4 . The system of claim 2 , wherein at least some of the plurality of dome members are disposed symmetrically relative to the helical thread.

5 . The system of claim 2 , wherein at least some of the plurality of dome members are positioned midway between adjacent windings of the helical thread.

6 . The system of claim 2 , wherein at least some of the plurality of dome members are disposed asymmetrically relative to the helical thread.

7 . The system of claim 2 , wherein the helical thread includes a first winding and a second winding adjacent to the first winding, wherein the first winding includes a first edge facing downstream, wherein the second winding includes a second edge facing upstream, and wherein at least some of the plurality of dome members are disposed closer to the first edge than to the second edge.

8 . The system of claim 2 , wherein the root has a first root diameter at the metering section and a second root diameter at a feed region, the second root diameter being different than the first root diameter.

9 . The system of claim 2 , wherein the helical thread projects a first distance radially outward from the root, wherein at least some of the plurality of dome members project a second distance radially outward from the root, and wherein the first distance is greater than the second distance.

10 . The system of claim 1 , wherein the screw is free of helical thread.

11 . The system of claim 1 , wherein the screw includes a discontinuous thread.

12 . The system of claim 1 , wherein the screw is designed to translate within the barrel.

13 . The system of claim 1 , wherein the screw includes a feed section and a transition section.

14 . The system of claim 13 , further comprising one or more additional dome members disposed along the feed section.

15 . The system of claim 13 , wherein the feed section is free of dome members.

16 . The system of claim 13 , further comprising one or more additional dome members disposed along the transition section.

17 . The system of claim 13 , wherein the transition section is free of dome members.

18 . A system for molding products, the system comprising:

a barrel containing a resin and a plurality of fibers;

wherein the resin includes a thermoplastic resin;

wherein at least some of the plurality of fibers include fibers having a length of at least 6 millimeters;

a screw disposed within the barrel, the screw including a screw root and a helical flight disposed about the screw root;

wherein the screw is designed to rotate and reciprocate within the barrel;

wherein the screw includes a feed zone, a transition zone, and a metering zone; and

a plurality of dome members coupled to the screw and disposed along the metering zone.

19 . The system of claim 18 , wherein at least some of the plurality of fibers include fibers having a length of about 6-12 millimeters.

20 . A system for molding products that include long fiber thermoplastic materials, the system comprising:

a barrel;

a hopper in communication with the barrel;

a screw disposed within the barrel, the screw being designed to rotate and translate/reciprocate within the barrel;

wherein the screw includes a metering section; and

a plurality of dome members coupled to the screw and disposed along the metering section.