PLASTIC INJECTION MOLD TOOLING AND A METHOD OF MANUFACTURE THEREOF

A METHOD OF MANUFACTURE THEREOF

The invention pertains to plastic injection mold tooling, and also la昭e forgings, formed from a low carbon mold steel having markedly increased hardening and hardenability properties in large sections as contrasted to currently available commercial products. The above attributes are obtained together with equal or better machinability and improved mold parting line wear. When manufactured in conjunction with a double melt process, this invention can improve significantly polishing characteristics and other attributes of molded parts in tooling sets.

BACKGROUND OF THE INVENTION

The place of plastics in the automotive industry has grown tremendously as it is the key to future high performance, more fuel efficient vehicles. Plastics offer designers and engineers multiple advantages in many applications by providing lightweight and versatile designs as well as lower manufacturing costs. The versatility of plastics can be expressed by the wide range of shapes and surfaces finishes now possible. However, this versatility would not be possible without quality plastic injection mold steels. The increasing demand fbr fuel efficient cars is pushing designers to create more aerodynamic cars, which in turn require larger complex plastic parts such as bumpers, dashboards and door panels. Other industries have similar requirements fbr plastic parts such as exterior furniture. Plastic injection molding is used fbr a fast paced production and tool steels are used fbr this application. The properties of a quality plastic injection mold steel vary from the mold manufacturer to the end-user. Good machinability as well as the ability to provide a good surface finish are important aspects fbr the mold manufacturer. However, uniform hardness is the key fbr the end-user to produce parts without shape distortion. As parts increase in size, molds have to be larger and still display these properties across the entire section.

SUMMARY OF THE INVENTION

A primary object of this invention is to provide plastic injection molding tooling sets having increased hardenability and hardness as contrasted to such sets currently available along with (1) equal or better machinability, (2) increased cleanliness together with good impact values and,