Method of injection molding a thin walled article

A method of injection molding an arcuately-shaped, thin walled article using a mold having first and second mold blocks which are mateable with one another to form a mold cavity therebetween, said mold cavity having a peripheral surface and first and second ends, a third mold block designed to mate with said first and second mold blocks and close off said first end of said mold cavity, said third mold block having an elongated core pin which extends into said mold cavity when said third mold block mates with said first and second mold blocks, a lifter mateable with said first and second mold blocks to close off said second end of said mold cavity, and said elongated core pin engageable with said lifter to assure that said core pin is radially spaced away from said peripheral surface of said mold cavity, said method comprising the steps of:

• a) moving said lifter into registration with said second mold block;
• b) moving said third mold block and attached core pin into registration with said second mold block such that said core pin mates with said lifter;
• c) closing said first and second mold blocks to form said mold cavity therebetween;
• d) filling said mold cavity with a molten material and allowing said molten material to solidify to form an arcuately-shaped, thin walled article;
• e) opening said mold by separating said first and second mold blocks;
• f) withdrawing said core pin from inside said arcuately-shaped, thin walled molded article;
• and
• g) moving said lifter away from registration with said second mold block and away from said arcuately-shaped, thin walled molded article.