Many Factors Impact Mold Longevity
Injection molding can be a cost-effective way to make your product idea a reality. However, it requires upfront tooling costs that can be in the tens of thousands of dollars or more, depending on the complexity of the mold and materials used. When making a sizable investment into your product, it is reasonable to ask, “how long does an injection mold last?”
There is no black-and-white answer. Mold lifespans vary based on several factors, including the mold materials, the workmanship of the mold builder, the polymers being molded, and the care and maintenance. Mold lifespans are not determined by months or years of use but instead by the number of production cycles. Molds can last from a few hundred to more than a million cycles.
The Society of Plastics Industry (SPI), now called the Plastic Industry Association (PIA), classifies molds based on the number of cycles they are expected to run. These classifications indicate the quality of a mold but do not guarantee it, as other factors can impact the mold’s lifespan. You may see these referred to as either SPI or PIA Classes.
Class 101 – These molds are built to exceed one million cycles – extremely high volume. These molds are the most expensive and are manufactured with the highest quality materials. Tool structure components must have a hardness of 28 Rc, and cavities and cores must have a minimum hardness of 48 Rc. Areas that move against one another should have a hardness difference of at least 4 Rc. Other mold details, such as heel blocks, wedge blocks, gibs, and slides, should be made of hardened tool steel. There are additional requirements for ejection, slides, temperature controls, and parting line locks.
Class 102 – These molds are built to achieve up to one million cycles – medium to high volume. The material hardness requirements for the tool structure components, cavities, and cores are the same as Class 10. Other functional details should be made of heat-treated steel. The most significant difference between Class 101 and Class 102 is that slide wear plates, guided ejection, corrosive-resistant plated cavities, and temperature control channels may not be required depending on the anticipated part quantity.
Class 103 – These molds are built for a maximum lifespan of 500,000 cycles – medium production volume. The mold base must be a minimum hardness of 8 Rc, and the cavity and cored must have a minimum hardness of 28 Rc.
Class 104 – These molds are built to not exceed 100,000 cycles – low production mold. This mold is best suited for non-abrasive materials. The mold base and cavities can be made from mild steel or aluminum.
Class 105 – These molds are built to last for not more than 500 cycles and typically for a limited number of prototypes. They are constructed in the least expensive manner possible and may use cast metal, epoxy, or other materials.
Factors Impacting How Long an Injection Mold Lasts
While the mold class is essential for determining its lifespan, how the molder treats the mold is equally important.
Injection Mold Material
Aluminum and steel are commonly used metals for molds. Aluminum is cheaper and more easily machined than steel. However, because it is softer, it wears much faster than a harder metal like steel. Coatings can help to limit wear as well.
Certain mold design elements can help keep the mold viable for a long time. Proper vents, for example, can help reduce the possibility of thermal stresses causing mold failure. Components that help eject the part, such as push guides, can reduce the stress on the mold.
Harsh and dirty manufacturing environments can reduce the longevity of your mold. A clean environment that doesn’t expose your mold to corrosive elements is preferred to achieve the longest lifespan.
The process used can impact lifespan. Using more clamping force that is required can deform and create wear on the mold. It can also close off vents leading, which exacerbates the clamping issue as more injection pressure is required and therefore increased clamping force, creating a circular dilemma. Slower cycle times create less wear on a mold than high-speed cycles. Proper temperature control can also help to protect the mold lifespan. If the time between each run doesn’t provide enough time for it to cool, damage can occur from the thermal stress.
Material Being Molded
Filled polymers have a higher wear factor than unfilled polymers.
Proper and routine scheduled maintenance is essential for mold longevity. Regularly cleaning, inspecting, stripping, and repairing molds will ensure the maximum life expectancy of the mold.
Since many of these factors are controlled by the molder, it is essential to work with a vendor with proven standards and reliability.
SEA-LECT Plastics: A Proven Partner
A great mold design is an essential part of the injection molding process. With an onsite tool and die shop, we excel at producing new builds and performing inserts changes, modifications, maintenance, and repairs to ensure you keep receiving high-quality parts. We can work with your existing molds or custom-build them following your specifications.
Each mold is built to precise specifications and to withstand the high pressures of injection molding. We can design molds quickly through our computer-aided manufacturing resources, rapid prototype technologies, and a first-class machine shop. With options for building in-house or with partners locally and abroad, you receive the best possible price and quality.
If your current molds are overseas, we can help you with mold recovery. Our American partners in China understand Chinese culture and language. They can visit your current supplier to retrieve your molds. We can then evaluate the mold’s condition and give you a quote for any repairs, cleaning, or modifications necessary to bring them up to the American standards for injection mold tooling and safety.