Understanding the 5 Types of SPI Mold Standards and Classifications

Published on July 28, 2023

Navigating the landscape of custom injection molding projects can be a daunting task, particularly when it comes to identifying whether a product is an appropriate fit for this specific process. An effective guide to this endeavor is understanding the classifications established by the Society of Plastic Industry (SPI). These categories, namely 101, 102, 103, 104, and 105, offer clear guidelines on the intricacies and complexities of injection molding standards.

The existence of the SPI mold standards is paramount to maintaining uniformity and consistency within the industry. They provide a standardized framework that manufacturers can align with, giving clear indications of what products are suitable for each class of molds. By adhering to these classifications, manufacturers can ensure the longevity and reliability of their molds, avoid costly manufacturing errors, and meet the high-quality expectations of the industry. These standards serve as a roadmap, guiding each project to successful completion and increasing overall efficiency.

The 5 SPI Mold Classes

  • Class 101: This is the most basic mold class and includes simple parts with few details. It also requires a limited number of cavities and cores that are compatible with the injection machine. Examples of products made in this class include bottle caps, stoppers, lids, and small containers.
  • Class 102: Class 102 molds offer more complexity than Class 101, but still not as much as the higher classes. It typically includes parts with more intricate details and varying wall thicknesses. Examples of products made in this class include automotive parts, medical device components, and consumer electronics.
  • Class 103: This is considered to be the standard for complexity in injection molding. Parts with several delicate features are common in this class, as are surface finishes and texturing. Examples of products made in this class include small handles, levers, hinges, and joints.
  • Class 104: This is the most advanced mold class and requires intricate parts with details that require high precision. It also includes molds for materials with properties such as low shrinkage rates and excellent performance. Examples of products made in this class include complex medical components, precision mechanical parts, and aerospace components.
  • Class 105: This is the highest mold complexity level and often requires high-performance materials to complete the desired product. It also demands multiple cores and cavities that are compatible with an injection machine. Examples of products made in this class include specialized tools, optical lenses, and components for high-performance machinery.

By understanding the five SPI Mold Classes, you can determine which type of mold is best suited for your custom injection molding needs. With a bit of research, and knowledge of these classes, you’ll be well on your way to a successful injection molded product!

Ready to embark on your custom injection molding journey? Spaulding Composites is here to guide you every step of the way. Our team has extensive knowledge of SPI mold standards and a passion for creating outstanding custom molded products. Get in touch with us today to learn more about how we can make your injection molding project a success.