Feedscrew for injection molding and extrusion

A feedscrew for a plastic material mixing apparatus comprising:

• an elongated body having a generally circular cross section and a longitudinal axis;
• a generally helical thread formed on at least a section of said body extending outwardly from said longitudinal axis with a constant pitch and having a land of a predetermined diameter;
• a first channel formed along a predetermined length of said section of said body by said thread, said first channel varying in depth at least once from a first maximum depth below said land to a first minimum depth below said land and back to said first maximum depth;
• and
• a second channel formed along said predetermined length of said section of said body in said first channel, said second channel varying in depth from a second minimum depth below said land to a second maximum depth below said land and back to said second minimum depth, said first maximum depth and said second minimum depth being at first common points along said longitudinal axis and said first minimum depth and said second maximum depth being at second common points along said longitudinal axis.

A feedscrew for a plastic material mixing apparatus comprising:

• an elongated body having a generally circular cross section and a longitudinal axis;
• a generally helical thread formed on said body extending outwardly from said longitudinal axis with a constant pitch and having a land of a predetermined diameter;
• a first channel formed along said body by said thread, said first channel alternately varying in depth between a first maximum depth a first predetermined distance below said land and a first minimum depth a second predetermined distance below said land;
• and
• a second channel formed along said body in approximately a center of said first channel and at said constant pitch, said second channel varying in depth between a second minimum depth said first predetermined distance below said land and a second maximum depth a third predetermined distance below said land, said first predetermined distance being greater than said second predetermined distance and said third predetermined distance being greater than said first predetermined distance.