Meaning
Pre-hardened tool steel plate assemblies provide the structural support and alignment framework for injection molding cavities and cores. This medium-carbon alloy steel is delivered pre-hardened to a typical hardness of thirty Rockwell C, allowing moldmakers to machine pockets, water lines, and runner systems without requiring subsequent heat treatment. This stability minimizes the risk of dimensional distortion during the mold fabrication process.
Material Properties
Machining properties and toughness make this steel the standard choice for the main structural plates of a mold. When selecting a mold base p20 steel, the material offers sufficient strength to resist the clamping forces of the injection press without flexing or compressing. This prevents flash along the parting line of the molded parts by maintaining a tight, parallel seal during high-pressure injection.
It also offers good thermal conductivity, which helps distribute heat evenly across the mold assembly to promote consistent cooling.
Tooling Lifespan
Medium-volume production runs are the primary application area for molds built with this steel. It can typically run hundreds of thousands of cycles before showing wear on sliding faces or pocket surfaces, unlike softer aluminum tools. If the mold must run highly abrasive or corrosive materials, toolmakers will often substitute harder alloys for the cavity inserts while keeping the structural base in this pre-hardened material.
Machining Efficiency
Eliminating the heat treatment step after machining reduces the lead time for producing new mold tools. Moldmakers can drill deep cooling channels and cut complex ejector plate systems without worrying about the steel warping or cracking during a later hardening cycle. This predictable machining behavior lowers the risk of tool failure during the manufacturing phase.
