The injection molding process is very popular due to its repeatability. It can create thousands of identical parts in a matter of seconds. It uses mold, which changes the molten material into the desired shape. Mold plays an integral role in the injection molding process. However, many people seem to have no idea when it comes to how long does an injection mold last.
You might hear people saying that injection molds can last for decades. Is this correct? Interestingly, the longevity of a mold depends on several factors. It can last anywhere from a few months to many years, depending on these factors. In this article, I will discuss all the aspects of mold’s life. So, let’s get started!
Basic Rundown of Injection Mold & its Working
Before discussing the life cycle, let’s take a bird’s-eye view of mold.
The mold is a hollow structure or tray consisting of cavities. Its shape and design are similar to our desired product. It is a small block that can be filled with material and then formed into parts. The mold consists of several internal components, including runners, a cooling system, and an ejection pin. It is made of strong materials such as steel or aluminum.
Undoubtedly, the mold plays a primary role in the injection molding process. Without it, the injection process is incomplete. Let’s discuss how injection molding plays a role in making parts. In this process, the molten material (plastic) is filled into this mold. This material cools, solidifies, and adopts the shape of the mold.
Once the molten material dries, we eject it using the ejection pin of the mold. Remember, the mold consists of two halves. When the mold is filled, the halves are closed. When the ejection of a part is required, the mold halves can be opened easily. The manufacturing of a mold is a complex process, as it involves many components.
The shape of the mold must be similar to the shape of the part you want to produce. Therefore, CAD software is used to make the mold design. Remember, for different parts, you’ll need multiple molds. One mold shape is similar to only one part. Mold should be durable and long-lasting, allowing it to handle high-volume production.
How Long Does an Injection Mold Last?
There is no fixed answer to this question. The life of an injection mold depends on several factors.
Mold can last for 5 to 8 years if it is not used frequently. However, if the usage is extensive, mold can last for 1 to 3 years. Remember, care and regular maintenance can enhance the life of the mold. Mold material also affects its life. The steel molds are durable and last longer than aluminum ones.
Primarily, the frequency of use determines the lifespan of mold. If you use mold once a week, it will be fine for a long time. It won’t wear out quickly. On the other hand, if you use it frequently throughout the day, it will start to deteriorate. Remember, the mold is filled with molten material. This material is very hot and can affect the mold every time it comes into contact with it.
Here is a table showing mold types, their usage frequency, and life:
| Mold Type | Frequency of Use | Expected Lifespan (Time) |
| Low-Use Mold | Occasionally (few times a year) | 5 to 8+ years |
| Medium-Use Mold | Weekly or monthly | 2 to 5 years |
| High-Use Mold | Daily (mass production) | 6 months to 2 years |
However, regular maintenance and care can increase the life of the mold. For example, you should clean the mold after every use. Similarly, you should expose it to moisture for an extended period to prevent it from rusting. All these precautions are small, but they have a positive impact on the life of molds. On average, molds last for 3 to 5 years if used consistently.
Injection Mold Life Cycle: How Many Cycles Per Mold?
Knowing the total number of mold cycles is a better way to estimate its lifespan. One cycle refers to a single use or a single instance. For example, you put molten material into a mold. This material solidifies, adopts the shape of the mold, and is then ejected from it. This is one complete shot.
On average, a mold can easily give around 100,000 to 500,000 cycles. A mold can even undergo as many as 1 million cycles in its lifetime. However, such molds are made with high-quality steel materials. Moreover, they are kept in check, and their regular maintenance is done promptly.
As I said earlier, the life of an injection mold depends on many factors. The same is true for the life cycles of molds. The Society of the Plastics Industry (SPI) has divided molds into different categories. Those categories are based on the number of cycles each mold gives. Here is the table showing those categories:
| Class or Category | Expected Life (shots) |
| 101 | 1 million+ |
| 102 | 500,000 – 1 million |
| 103 | 250,000 – 500,000 |
| 104 | < 100,000 |
| 105 | < 500 |
The mold from class 101 is used on a large scale. They are made with heavy-duty materials and last for many years. On the other hand, molds from Class 104 are less durable and can only be used at a smaller scale. Remember, Class 105 molds are prototypes used for testing purposes. Molds from each class offer a specific number of cycles.
Steel vs. Aluminum Injection Molds Lifespan
Steel material is significantly stronger than aluminum. It can withstand extreme pressure, repeated usage, and high temperatures. So, mold made with this material is very durable and lasts longer. Remember, aluminum is a material that lacks ideal strength. When exposed to pressure regularly, this material can undergo deterioration.
Therefore, molds made of aluminum are less durable and have a shorter lifespan. Their wear and tear is also prevalent. Generally, the aluminum molds start to show deterioration after 10000 cycles. The steel molds can remain in good shape even after 500,000 cycles. However, the steel material is costly, which can be a drawback.
Here is a table showing the comparison of steel and aluminum molds:
| Steel Mold | Aluminum Mold |
| Lasts 500,000 to 1M+ cycles | Lasts 5,000 to 100,000 cycles |
| Lifespan of 5 to 10+ years | Lifespan of 1 to 3 years |
| Expensive upfront | Cheaper upfront |
| Longer to manufacture | Faster to manufacture |
| Needs advanced maintenance tools | Easier to machine and repair |
| Slower cooling – longer cycle time | Faster cooling – shorter cycle time |
| Best for high-volume production | Best for low to medium volume runs |
What Factors Influence the Lifespan of Injection Molds?
As previously mentioned, the mold life varies depending on different factors. If you control those factors, the life of molds can be extended and vice versa. In the section below, I’ll explain those factors:
1- Mold Material
The material of the mold affects its durability and lifespan. Generally, steel and aluminum are two popular materials used in the manufacture of molds. Steel molds are very durable and can give cycles of over one million. Different types of steel, such as P20, P20, and stainless, are used in molds. The aluminum molds are less durable and can withstand fewer than 100,000 cycles. I recommend choosing steel molds if you want to produce at a large scale.
2- Mold Design & Quality
The quality of the mold determines its longevity. For example, high-quality molds come with a smooth design and last longer. They come with an even flow of fluid in their cavities. Their heating and cooling mechanism is very efficient. Such molds do not wear quickly. Molds with inefficient cooling channels will remain under heat for a long duration. Its life would be shortened due to this excessive heat exposure. Quality molds with optimal design and proper care make the best combination.
3- Injection Pressure & Temperature
Improper pressure and temperature can significantly reduce the life of molds. Remember, the mold undergoes pressure and temperature when used in injection molding. If the pressure in the mold is too high, it can cause cracks in the mold.
These cracks, over time, expand and affect the mold. Similarly, temperatures that are too low or too high also hurt mold. If the temperature is too high, it can weaken the walls and surface of the mold. If it is too low, the molten material won’t flow evenly, resulting in high pressure on some portions of the molds.
4- Maintenance and Cleaning
Proper maintenance is a crucial factor that can increase the life of a mold. As you know, mold undergoes high pressure, temperature, and molten plastics in each cycle. The plastic material leaves some residue in the mold.
If this residue remains unchecked, it will affect the quality of molds. Moreover, molds should not be stored in moist conditions. If you see any sign of rust, take immediate steps to remove it. I highly recommend keeping the ejection pin lubricated. All these steps will lead to a longer lifespan of molds.
5- Operator Skill & Expertise
The skill and experience of the operator also play a role in increasing the life of the mold. If the operator is not skilled, he can mishandle the mold. Generally, operators adjust the temperature, pressure, and other parameters as needed.
If this setting is wrong, the mold would be exposed to harsh conditions. As a result, the mold life will be significantly affected. Suppose the operator forces the part out of the mold without using an ejection pin. This can result in damage to the internal parts of molds. Therefore, having a skillful operator helps increase the lifespan of molds.
6- Environmental Conditions
Molds that are exposed to bad environmental conditions are generally less durable. So it starts to wear out quickly. Even mold made with high-quality steel material cannot thrive in unfavorable environments.
If the mold remains exposed to moisture, it can get rusty. Some people claim that stainless steel molds are resistant to rust, which is indeed true. However, consistent exposure to moisture can still result in rusting of mold. I highly recommend storing the mold in dry places. Moreover, you should prevent other contaminants from coming into contact with the mold.
How to Maintain Injection Molds To Extend Their Lifespan?
Generally, molds last for 1 to 3 years under extreme usage conditions. However, if you take care of them, their life can be extended even up to 10 years. Here are some key tips that will help you extend the lifespan of the molds:
- First, clean the mold after every cycle. This will prevent the buildup of plastics or rubber residue.
- The mold consists of many internal parts. Those include ejection pins, slides, and moving cores, among others. You should keep all these parts lubricated to ensure smooth operation.
- The mold features cooling channels that direct water. You should keep these channels clean so that the water moves smoothly. This will keep the mold at an optimal temperature.
- If the mold is exposed to moisture for an extended period, it can become discolored and develop a rusty appearance. Therefore, it is best to keep the mold in dry places. Moreover, you can also apply a coat of paint to protect the mold from corrosion. You can also use anti-rust spray on the mold as a precautionary measure.
- Regular inspections are key, as they keep you informed about the condition of the mold. After each use, inspect the mold for any signs of damage, such as wrapping, cracking, or defects. If there is any, you should act immediately to remove that defect. Regular inspection helps maintain the mold in good condition for an extended period.
Conclusion
The role of mold is crucial in the injection molding process. A durable and long-lasting mold makes the process more cost-effective and vice versa. Generally, a high-quality product can last for up to 5 to 6 years, provided it is well-maintained. It will offer around 500000 cycles in its life.
Remember, if you don’t maintain mold, it can deteriorate quickly. Why? Because it faces extreme heat and pressure in each cycle. Multiple factors affect the lifespan of an injection mold. Those include mold material, design, and overall maintenance. In the concluding section, you’ll also find some practical tips that help extend the life of molds.