Hi, I am just reading books on injection molding and understand some of the basics, but am not sure about an internal mold design feature regarding locktabs. In a harness connector that uses plastic harness ends with locking spade electrical connectors (such as http://www.swedishtreasures.com/958211.jpg), how are the molds designed to create the locking form for the spade connector, yet still allow release from a mold cavity? I know in simple sand casting for aluminum foundry use they use mold cores, but am not sure how this would be accomplished with plastics. If anyone can just point me to a link that I am not finding myself, I am happy to do all the reading. Any help is appreciated.

Thanks, Derek

Go to a junkyard or an auto repair shop and snag some wiring harnesses.  Burned or cut ones are okay.  What you want to do is remove the connector inserts and study the connector shells.

You will find that the mold to make the shell is usually modular, with an array of pins entering the cavity from two opposite faces, the wire entry face and the mating face.  The locking detent features are almost always formed by the interaction of the ends of two facing pins.  

The molds are simple, in the sense that there is no funny business like collapsing cores or side pulls.  They are complex, in the sense that they are built from many individual pieces.  They are all pretty darn clever.

Mike Halloran
Pembroke Pines, FL, USA