Should You Repair or Replace Your Injection Mold?
Injection molding is one of the most commonly used manufacturing processes for mass-producing plastic parts. Once you’ve perfected the mold for your part, it can make thousands to millions of pieces before undergoing the injection mold repair process.
Creating custom molds can be expensive, so you’ll want to make sure you invest in a high-quality mold to maximize your profits and time. However, no mold will last forever, and there will come a day when you have to either repair or replace it. So, how do you know when it’s time for a repair? What does the repair process look like? When is it better to scrap it and make a new one? Let’s dive into the specifics.
Injection Mold Design Affects Longevity
The design process plays a huge role in how long your injection mold will last. Every decision — from the SPI mold grade, what material you use to the thickness of the mold walls — affects the lifespan of your mold. For example, steel molds will last longer than aluminum molds. Steel molds can be heat treated after they’re created, which makes them more resistant to wear. Conversely, aluminum molds cost less but are ill-suited to make high-volume parts with tight tolerances.
Other considerations such as the thermal balance and gating system can directly affect the longevity of the mold. Thermal stresses are one of the most common causes of mold failure; introducing design considerations like proper vents can reduce the negative effects of thermal stresses.
Your chosen injection molding partner will likely have an in-house engineering team, meaning you may not have much control over the specifics of the mold. That’s why it’s imperative to partner with an experienced injection molding company that employs a skilled engineering team to design the best, longest-lasting mold possible.
How Injection Molds are Damaged
There are quite a few ways injection molds can be damaged. Because you won’t have control over your mold on the injection molding floor, you’ll need to trust your chosen injection molding partner to educate its employees on proper mold care. Let’s cover some of the most common reasons why injection molds are damaged.
Using metal tools to remove stuck parts will cause scratches, resulting in appearance defects and can cause the part to be out of tolerance. Additionally, failure to lubricate moving components will cause galling and make the component seize. Even small things like wiping a mold with an improper rag can cause slight to major damage.
Improper processing covers a wide variety of accidents that may happen on the injection molding floor. When a mold is inside the injection molding machine, a process technician may use too much injection pressure and flash the mold. The flash can force its way between the leader pins and bushings, down ejector pinholes, or into vertical separations, which can force the side walls out or move around slide mechanisms and cams. This can lock the mold in place as it tries to open.
If a technician allows the nozzle to drool, it may result in material adhering to the cavity set, which can cause damage when the mold closes on it. Additionally, if the mold temperature is not controlled during the process, it may cause a portion of the mold to run at a higher temperature. This will result in thermal expansion, causing galling and swelling.
When to Pursue Injection Mold Repair
Injection molds are only built to last a certain number of cycles based on their class specification. The Plastics Industry Association (formerly known as the Society of the Plastics Industry) breaks these specifications up into five categories.
Class 101 – rated for 1,000,000+ cycles
Class 102 – not to exceed 1,000,000 cycles
Class 103 – under 500,000 cycles
Class 104 – less than 100,000 cycles
Class 105 – less than 500 cycles
The frequency of injection mold repair will depend on the class of your mold and how many parts you’re producing on a regular basis. Plastic injection molds are remarkable manufacturing devices, withstanding tons of pressure and heat every day. However, it’s inevitable that some will crash, seize, break, or need maintenance. So, how do you know when a mold needs maintenance or repair? Some tell-tale signs include:
Voids or depressions from non-uniform heating or cooling due to plugged lines
Burrs and flashing caused when excess plastic seeps into gaps in the mold or mostly worn-down parting lines or shut offs
When you work with SEA-LECT Plastics for your injection molding needs, you won’t have to worry about these issues. As soon as your mold goes into production, we assign it to a preventative maintenance schedule. This helps us keep production running efficiently and usually prevents unexpected costly repairs. We always communicate with you before we work on your mold.
The Injection Mold Repair Process
The mold repair process usually involves troubleshooting, mold disassembly, and a corrective action process. These corrective actions may include flash repair, welding, and alignment, along with cavity venting, hot runner, and ejector system repairs.
When is a Complete Replacement Necessary?
At a certain point in the mold’s life, it’s not worth the time and money to rework the tooling, replace components, or repair damage. If you’re seeing significant flashing issues, dimensional changes over time, cooling problems, damaged tooling surfaces, ejection system wear, or lock damage, it may be time to completely replace your mold.
Work with the Injection Mold Repair Experts
For the last 30 years, SEA-LECT Plastics has been providing injection molding services for companies in various industries. As an experienced injection molding company with an ISO 9001:2015 certification, we’re dedicated to providing the highest quality products to meet your unique challenges. We’ll help you design a custom mold that will last and make improvements when needed.
Want to learn more about injection mold repair and what SEA-LECT Plastics can do for you? Contact one of our helpful team members here.