An injection mold has a lower mold half having a chamber at a top thereof. A holding plate has a top within the chamber formed with a plurality of holding slots. The holding slots extend frontward and rearward. A positioning plate is attached to a front surface of the holding plate, an upper portion of which within the chamber has a plurality of positioning holes at a front surface thereof. A fixing plate disposed rearward of the holding plate has a plurality of through holes at a top thereof. A plurality of first positioning rods is mounted to the installing holes, each of which defines a free end extending beyond the top of the fixing plate. A free end of each of a plurality of second positioning rods is capable of inserting into the positioning hole. An upper mold half is engaged with the lower mold half.