Insert Molding is a process that enables components such as terminals, pins, studs, and fasteners, to be molded into a part. Insert molding allows the design engineer options he or she may not have thought possible.
Insert molding is not as easy as you might think and it takes carefull attention to detail when designing around this process. Common alternative approachs are to post-mold heat stake or ultra sonic weld the inserts into the plastic parts but this requires an extra step which usually means added cost.
If you are designing a device or an enclosure that requires inserts to be added for functional or assembly reasons you will need to look at your options carefully to determine which approach is best.