Injection Tooling Specifications
The tool specification guidelines listed and edited below were developed, more then 40
years ago, by the U.S. Society of Plastic Engineers (SPE). The intent was to try and
have simplified definitions, of the type of injection mold for thermoplastics that would be
required to meet certain production needs. This classification, aged as it is, is still often
referred to in the toolmaking industry.
Class 101 Tool – Lifetime cycles of one million or more.
• Tool base and structure components, to have a minimum hardness of 28 Rc.
• Cavity and cores must be Stainless Steel hardened to a minimum of 48 Rc. All other
details, such as sub-inserts, slides, heel blocks, gibs, wedge blocks, lifters, etc. should
also be made of hardened tool steels.
• Ejection must be guided.
• Slides and Cams must have wear plates.
• Temperature control provisions to be in cavities, cores and cams wherever possible.
Class 102 Tool – Lifetime cycles to be below one million cycles
• Tool base and structure components, to have a minimum hardness of 28 Rc.
• Cavities and cores should be hardened to a minimum of 48 Rc range. All other
functional details should be made of materials that can be heat treated.
• Ejection should be guided.
• Temperature control provisions to be in cavities, cores and cams wherever possible.
Class 103 Tool – Lifetime cycles of less than 500,000 cycles.
• Tool base and structure components, must have a minimum hardness of 18 Rc
• Cavity and cores must have a hardness of 28 Rc or higher.
• Ejection should be guided.
• All other extras are optional.
Class 104 Tool – Lifetime cycles of less than 100,000 cycles.
• Tool base, and structure components, can be of mild steel or aluminum.
• Cavities can be of aluminum, mild steel or any other agreed upon material.
Class 105 Tool – Lifetime cycles of less than 500 cycles.
• Tool to be constructed in the least expensive manner possible to produce a very
limited quantity of prototype parts.
• All components are optional