Tool Steel Selection Guidelines for High Volume Injection Moulding Tooling Baseline Fabrication
High-volume injection moulding baseline tooling demands martensitic stainless or pre-hardened steels matched to polymer abrasiveness and cycle volume.
Plasma Nitriding
Meaning
Thermochemical diffusion processes using ionized gas increase the surface hardness and wear resistance of steel components without affecting the core properties. Successful plasma nitriding treats the surfaces of cores, cavities, bushings and ejector pins to extend tool life in abrasive environments. The process operates at lower temperatures than traditional gas nitriding, which reduces the risk of tool distortion.
Surface Hardness
Formation of a hard nitrogen-rich layer on the exterior of the steel provides a barrier against friction and mechanical wear. The process of plasma nitriding creates a case hardness that can exceed 60 Rockwell C depending on the base alloy.
Diffusion Layer
Depth of the hardened zone is determined by the processing time and the voltage applied within the vacuum chamber. This layer remains integrated with the base metal and does not flake off under the high pressures of the injection cycle. This integrity makes the treatment ideal for sliding components like slides and lifters that face constant metal-to-metal contact.
Wear Resistance
Enhanced durability allows a moulder to run millions of cycles with glass-filled resins before the tool shows signs of erosion. Parts produced from a nitrided tool maintain better dimensional consistency over the life of the project. The reduction in friction also assists in the ejection of parts with low draft angles or sticky geometries.