Injection Mold Specifications

The tool specification guidelines listed 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. The resulting classification, even if aged as it is, is still often referred to in the toolmaking industry. The guidelines noted are proposed to be just a reference, that may vary slightly, on a project by project basis or depending on specific requirements. The different classifications will dictate differences in tool design, construction, materials, and components and following, is an edited version of its original text. Class 101 Tool – Lifetime cycles of one million or more. The tool is to be designed and built to meet high production requirements. It should be the highest priced tool and is to be manufactured with the highest quality of materials • Detailed tool design is required. • Tool base and structure components, to have a minimum hardness of 28 Rc. • Cavity and cores must be 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 must have wear plates. • Temperature control provisions to be in cavities, cores and cams wherever possible. • Over the life of a tool, corrosion in the cooling channels decreases cooling efficiency thus degrading part quality and increasing cycle time. It is therefore recommended that plates or inserts containing cooling channels be of a corrosive resistant material or treated to prevent corrosion. • Parting line locks are required on all tools. Class 102 Tool – Lifetime cycles to be below one million cycles. The mold is to be designed and built to meet medium to high production requirements. It should be a high quality, fairly high priced tool. • Detailed tool design is required. • 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. • Parting line locks are recommended. • The following items may, or may not, be required depending on the ultimate production quantities anticipated. It is recommended that those items desired be made a firm requirement for quoting purposes. • Corrosive resistant temperature control channels Class 103 Tool – Lifetime cycles of less than 500,000 cycles. The mold is to be designed and built to meet medium production requirements. • Detailed tool design recommended. • 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. • All other extras are optional. Class 104 Tool – Lifetime cycles of less than 100,000 cycles. The tool is to be designed and built to meet medium production requirements, or to be used only for limited production, preferably with non-abrasive materials. • Tool design recommended. • 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. The tool is to be designed and manufactured to meet a prototype production only. Description: Prototype only. Tool to be constructed in the least expensive manner possible to produce a very limited quantity of prototype parts. • All components are optional