Four Factors Affecting Injection Mold Tooling Life

Injection mold tool life refers to the number of production cycles that an plastic injection mold can complete before it requires repair or replacement. Each cycle includes closing the mold, injecting molten plastic, cooling, opening the mold, and removing the finished part. It can be difficult to predict tool lifespan, but Alpine Mold can assist with selecting the appropriate tool for prototyping, low, medium, or high-volume production. In this blog, we will discuss how to estimate the expected life of an injection mould by SPI mould classifications and what factors affect Injection Mold Tooling Life.

How to Estimate the Expected Life of an Injection Mold Tooling?

The lifespan of plastic injection molds can last from hundreds to over a million cycles. The life cycle of injection mold tooling is classified into five categories by the Society of Plastics Industry (SPI). The classifications are based on production volume and number of cycles. We can use SPI mold classifications to estimate the life cycle of an injection mould. These classes are covered in detail in the following sections, along with information about tool materials and design factors that impact tool life.

SPI Class 101 molds

SPI Class 101 molds are high-volume production molds that are designed for durability and long life. They are typically made from hardened steel, have a hardness of RC 48-52, and are capable of producing more than one million cycles. Class 101 molds may have multiple cavities, advanced gating systems, and complex part geometries. Due to their high production volume, Class 101 molds are often used for products with high demand, such as consumer goods and automotive parts.

SPI Class 102 molds

SPI Class 102 molds are designed for medium-to-high volume production. These molds are capable of producing between 500,000 and one million cycles. Class 102 molds have more basic gating than Class 101 molds and typically have fewer cavities. They are often used for products with moderate demand, such as small appliances and electronic components.

SPI Class 103 molds

SPI Class 103 molds are designed for medium volume production. They are capable of producing under 500,000 cycles. Class 103 molds have even simpler gating and fewer cavities than Class 102 molds, making them more cost-effective for lower volume production runs. They are often used for products with lower demand, such as toys and household items.

SPI Class 104 molds

SPI Class 104 molds are designed for low volume production. They are capable of producing less than 100,000 cycles. Class 104 molds are the most cost-effective option for low volume production runs, but they have a shorter life cycle than the higher classes of molds. They may use softer materials, such as aluminum or epoxy, to reduce costs. Class 104 molds are often used for custom or specialized products, such as medical devices or aerospace components.

SPI Class 105 molds

SPI Class 105 molds are designed for prototyping. They are capable of producing less than 500 cycles and are typically made from soft metals or plastic. Class 105 molds are the least expensive and quickest option for producing small quantities of parts for testing and evaluation. They are often used for design verification and validation, and to create samples for marketing and sales purposes. Due to their short life cycle, Class 105 molds are not recommended for high-volume production.

What Factors Affect Injection Mold Tooling Lifespan?

SPI mold classes provide a useful way to compare injection molds life, but four main factors ultimately determine injection mold lifespan.

1. Injection Mold Material and Construction

Injection mold materials fall into three categories: aluminum, soft/semi-hardened steel, and hardened steel. Each category has different grades that determine the expected tooling life. For instance, aluminum tooling typically lasts for 10,000 shots or less, but the harder 7000 series aluminum molds may last longer. Steel molds have a longer lifespan than aluminum molds and are often used for high-volume production runs. The specific material used for a mold will depend on factors such as production volume, plastic material, and part design.

Soft and semi-hardened steels are P20, 718H, and NAK80. These materials have different levels of hardness and are suited for different types of production runs.  P20 is harder than most aluminum grades, it can support 50,000 to 100,000 shots. P20 is commonly used for low to medium production runs, while 718H is slightly harder and is often used for medium to high production runs. NAK80 is a semi-hardened tool steel that is typically used for high-volume production runs and is well-suited for parts with complex geometries.

Hardened steels for injection mold tooling include H13 and S136 stainless steel. H13 has an expected tooling life between 500,000 and 1 million shots, while S136 stainless steel can last for over 1 million shots. The specific material used for an injection mold tooling will depend on factors such as production volume and part complexity.

2. Plastic Material and Part Design

The plastic material used for injection molding impacts both tooling and molding life. Glass-filled resins, for instance, are abrasive and can wear out injection molds more quickly. The specific combination of mold material and plastic material is also a factor. Corrosive plastic grades such as PVC or POM can cause aluminum molds to wear away quickly, but molds made of S136 hardened steel can resist the corrosive chemicals found in these polymers. Thick-walled part designs also contribute to mold wear, since these parts typically require longer cycle times during the injection molding process. Proper material selection and design considerations are essential for maximizing mold life and minimizing wear and tear.

3. Processing Skill and Environment

Proper temperature control and clamping force are essential for extending the tooling life of plastic injection molds. Excessive clamping force or premature opening of clamps or vents can cause mold damage. Overlocking, poor tool alignment, excessive ejector stroke, and over-pressurization of the plastic material can also contribute to premature wear of the mold.

The environment in which the mold is used also affects its lifespan. Molds used in harsh, dirty environments will wear out more quickly than those used in cleanrooms. It's important to use an injection mold tooling only in the environment for which it was designed to avoid premature wear.

4. Cleaning, Lubrication, and Maintenance

The frequency of cleaning and lubrication depends on factors such as production volume, mold type, plastic material, and operating conditions. Cleaning method should be carefully chosen to avoid damage to the mold's surface and protective coatings. Harsh or abrasive cleaners should be avoided. Lubrication is also important for moving parts like ejector pins, slides, and cores. However, over-lubrication can attract dirt and debris, leading to contamination and increased wear.

The relationship between mold maintenance and tooling life is crucial. Regular cleaning and lubrication are essential, but injection mold manufacturer must also schedule time for inspections and maintenance, even if it means taking a mold out of service. Recording the mold maintenance services is best practice to detect future issues. This can be done as frequently as once every few days. Preventive maintenance may be inconvenient, but it helps molders and customers avoid missing deadlines due to unplanned mold maintenance.

Conclusion

In this article, we discussed the lifespan of injection mold tooling. The lifespan of injection mold tooling is influenced by factors such as mold material and structure, plastic material and product design, operation and environment, cleaning, lubrication, and maintenance. By ensuring that the mold meets the requirements of the parts, using appropriate mold operating conditions, regularly cleaning the mold, inspecting the mold, and using coatings on the mold, the lifespan of injection molds can be extended. The life cycle of injection molding tooling is classified into five categories. However, regardless of the level of SPI molds, regular maintenance should be carried out.

Contact Alpine Mold

Alpine Mold is one of leading plastic injection mold tooling manufacturers in China. We can help you with developing a long-lasting mold for your injection molded parts, Our injection mold experts will collaborate with you to comprehend your requirements and take the necessary steps to ensure your mold can last the lifetime of your project. Upload your part design and get a free quote today!