Understanding Injection Mold Life: Spi Classes And Key Longevity Factors

By Author: Ryan
Total Articles: 13
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An injection mold's life is the number of manufacturing cycles it can complete before needing to be replaced or repaired. A manufacturing cycle includes shutting the mould, injecting a "shot" of molten plastic material, cooling, opening the mould, and removing the item. Predicting the lifespan of an injection mould is difficult, but Mctgroups may assist you in selecting the appropriate Injection mold tooling – whether for prototype, low, medium, or high-volume manufacturing.


What is the life cycle of injection moulding tools?


The Society of the Plastics Industry (SPI), a trade body that has rebranded as plastics, distinguishes five types of injection moulds. These classes make it easy to compare plastic injection moulding tooling in terms of production volume, which is a relative measurement, and production cycles, which represent a range of numbers.


SPI Class 101 Moulds


SPI Class 101 moulds are the most costly and designed to survive over 1 million production cycles while producing ...
... plastic components with strict tolerances and complicated geometry. These injection moulds are made of high-quality steel and, if sliders are used, come with wear plates. Class 101 moulds have a minimum hardness of 48 RC for the cavities and cores, and 28 RC for the tool components.


SPI Class 102 Moulds


SPI Class 102 Injection mold can create medium-to-large quantities of plastic components with an excellent surface polish. Despite being manufactured of lower-grade steel than Class 101 moulds, SPI Class 102 moulds are designed for medium-to-high quantities, with cycles ranging from 500,000 to one million. Class 102 moulds are cheaper than Class 101 moulds, but more expensive than the other SPI mould classes.


SPI Class 103 Moulds


SPI Class 103 moulds are intended to make plastic components with reduced cosmetic standards for medium-volume manufacturing runs of less than 500,000 cycles. SPI Class 103 moulds require more frequent maintenance over time due to the poorer quality of the materials used. The minimum hardness of cavities and cores is 28 RC, whereas the minimum hardness of tool construction components is 18 RC.


SPI Class 104 Moulds


SPI Class 104 moulds are intended for modest quantities and less than 100,000 manufacturing cycles. Despite being composed of lower-quality and less expensive materials, Class 104 moulds nonetheless have hardened steel inserts, high-quality surface finishes, and strict tolerances. These moulds may incorporate elements like hot runners and lifters.


SPI Class 105 Moulds


SPI Class 105 moulds are identical to Class 104 moulds in terms of precision and quality, however they are intended for prototype rather than production. Typically, this sort of plastic injection moulding tooling lasts less than 500 cycles. These moulds are typically made of cast metal and may include inserts made of hardened steel. Moulds classified as SPI Class 105 are the least costly.


What Factors Determine Injection Mould Lifespan?


SPI mould classifications provide a useful foundation for comparing mould life. Ultimately, four elements impact Injection mold tooling longevity.


Injection mould material and construction


Plastic materials and component design


Processing skills and surroundings


Cleaning, Lubrication, and Maintenance