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The 5 Types of SPI Mold Classifications and Standards

Posted by Dennis McGuigan on Mar 20, 2019 9:55:00 AM
Dennis McGuigan

SPI Mold Classifications and Standards

When you approach a custom injection molder to produce complex plastic parts or components, determining if the product is suitable for a streamlined injection molding process is one of the first steps.

Experienced injection molders will ask a series of questions to better understand your project needs from multiple perspectives – design, purpose and objectives – to first determine overall moldability, and then to confirm what type of mold is best suited for the job. Using mold classifications to determine the correct mold type is crucial to achieving quality, production and cost objectives.

[Free Guide] Tooling Design for Injection Molding

Standard molds are defined by the Plastics Industry Association (formerly known as the Society of Plastics Industry or SPI). These mold standards are categorized into five classifications to guide quotes and orders into uniform mold types:



Production level



Class 101 Mold

1 million or more Extremely high Extremely high production and fast cycle times Class 101 molds are the highest priced and made with only the highest quality materials 

Class 102 Mold

Not exceeding 1 million Medium to high Good for parts with abrasive materials and/or tight tolerances Class 102 molds are fairly high priced and made with materials of high quality

Class 103 Mold

Not exceeding 500,000 Medium A very popular mold for low to medium production parts Class 103 molds fall within common price ranges 

Class 104 Mold

Not exceeding 100,000 Low Good for limited-production parts with non-abrasive materials Class 104 molds fall within low to moderate price ranges 

Class 105 Mold

Not exceeding 500 Very low Prototype only  Class 105 molds are built inexpensively to produce a very limited number of product prototypes

Simply reviewing a mold classification chart isn't enough, however, since each mold classification has unique parameters. It’s essential that you partner with a molder that is knowledgeable on these mold standards and the classification spectrum. The molder's guidance can determine the best type of mold that meets your production life, cost and quality objectives.


Because of the complex nature of our customers’ products, Kaysun typically deals with applications that fall within Classes 101 and 102 for long-life production. Yet, our broad-based experience in custom injection molding makes us the preferred choice for consulting on all projects for which high-quality and high-volume tools are required.

Find out how tooling design plays an essential role in achieving desired injection molding outcomes – from the different stages of the tooling process to the key components of tooling design  in our whitepaper, Tooling Design for Injection Molding. Click the button below to download your free copy.

Tooling Design for Custom Injection Molding

Topics: Injection Molding Process, Tooling / Molds

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