How many types of cooling systems are there for injection molds?

Table of Contents

The cooling system of injection molds can be divided into air cooling, water cooling and oil cooling depending on the medium, but the most common is the water cooling system.

Types and characteristics of cooling systems

The main types of cooling systems are air, water and oil. Each type has its own advantages and disadvantages.

Air cooling is the most common type because it is the cheapest. However, it is also the least effective.

Water cooling is more effective than air cooling, but it is more expensive. Oil cooling is the most effective, but it is also the most expensive.

What is an injection mold cooling system?

A cooling system is a system of water channels in a mold that is connected to an external water source, forming one or more water circuits in the injection molds as needed.

The water channels are filled with coolant and circulated continuously to bring excess heat from the injection mold outside itself.

One of the most important aspects of injection molding production is the cooling system. The cooling system is responsible for cooling the heated plastic so that it can solidify and be molded into the desired shape.

Without a proper cooling system, the plastic will not solidify and cannot be used.

What does the injection mold cooling system do?

Impact on product quality

In the injection molding process, the cooling channel is used to control the temperature of the mold.

Fluctuations in the cooling channel temperature directly affect the shrinkage, deformation, dimensional stability, mechanical strength, residual cracks, surface quality, etc. of the product.

Mainly include: surface gloss, residual stress, crystallinity and thermal deflection.

Impact on the production cycle

The injection molding cycle is mainly composed of the following steps. The reduction of cooling time means the increase of injection molding efficiency

Why is the cooling system of injection molding important?

The cooling system of injection molding plays a key role in the quality of the final product. The cooling system needs to be able to quickly cool the heated plastic so that it can solidify in the mold.

If the cooling system is not effective, the plastic will not solidify properly and the quality of the final product will be poor.

In addition, the cooling system needs to be able to cool the mold evenly so that there are no hot spots. Hot spots can cause deformation and distortion of the plastic, again leading to a lower quality of the final product.

Therefore, having an effective cooling system for injection molding is critical in order to produce a high quality product.

Injection molding is a complex process that requires precise control of many variables. To ensure that your injection molding process runs smoothly and efficiently, it is important to invest in a quality cooling system.

Injection molding cooling systems help regulate the temperature of the molten plastic, as well as the mold itself. This helps prevent defects in the finished product and ensures a consistent level of quality.

In addition, the cooling system helps to reduce production time and keeps the plastic in a moldable state for a longer period of time.

The design of the cooling system for injection molds is very important. Cooling time accounts for 70% – 80% of the injection molding cycle, and a well-designed cooling system can significantly reduce molding time and increase productivity.

A poorly designed cooling system can prolong molding time and increase production costs. Injection mold temperature has a great impact on mold shrinkage, dimensional stability, deformation, internal stress and surface quality.

What are the factors for choosing the right injection molding cooling system?

The injection molding cooling system is one of the most important factors in the injection molding process. It is responsible for removing heat from the plastic part so that it can solidify faster and more uniformly.

The heated plastic is injected onto the first plate, where it is cooled by the recirculating cooling system. The plastic then moves to the next plate, where it is cooled again. This process is repeated until the plastic is cooled enough to solidify and mold.

The injection mold cooling system is critical to injection molding and must be carefully monitored to ensure it is working properly.

In order to select the correct cooling system for your injection molding application, you need to consider several factors.

  • The type of plastic to be injection molded
  • The size of the injection molding machine
  • The cycle time of the injection molding machine
  • Injection molding production volume
  • The injection molding environment (ambient temperature, humidity, etc.)
  • The size and shape of the injection molded products
  • Tolerance requirements for injection molded products
  • Surface treatment requirements of injection molded products

Design principles of cooling system for injection mold

In order to improve the productivity and ensure the quality of the products, the cooling system of the mold is designed to ensure the uniform cooling of the plastic parts as the basic principle. Specific design attention to the following points.

1. The number of cooling water holes is as large as possible and the size is as large as possible. The temperature of the surface of the cavity is closely related to the size and density of the cooling water holes.

Cooling water hole diameter, hole spacing is small, the surface temperature of the cavity uniform.

2. The distance from the cooling water hole to the surface of the cavity should be appropriate. The distance of the hole wall from the cavity should be appropriate, generally greater than 10mm, commonly used 12 ~ 15mm. Too close, the surface temperature of the cavity is not uniform; too far, thermal resistance, low cooling efficiency.

When the wall thickness of the plastic part is uniform, the distance between the cooling water hole and the surface of the cavity is best the same. When the wall thickness of the plastic part is not uniform, the cooling water channel at the thick wall should be appropriately close to the cavity.

3. Water and material in parallel to strengthen the cooling at the gate. The high temperature plastic melt is filled into the cavity by the gate during molding, the mold temperature near the gate is higher and the temperature at the end of the material flow is lower.

The cooling water inlet is located near the gate, so that the overall flow direction of the cooling water tends to be the same as the material flow direction in the cavity (water-material parallel), and the cooling is more uniform.

4. The temperature difference between the inlet water and the outlet water should not be too large. If the difference between the inlet and outlet temperatures is too large, it will make the temperature distribution of the mold uneven.

In order to obtain the same cooling speed of the whole product, the arrangement of the cooling water channel should be set reasonably to reduce the temperature difference between the inlet and outlet water.

5. Cooling water hole arrangement should be reasonable. Cooling water channel as far as possible in accordance with the shape of the cavity arrangement, the shape of different plastic parts, cooling water channel location is different, for example:
a. Moving and fixed mold are from the cavity equal distance drilling.

b. Shallow shell plastic parts fixed mold drilling, dynamic mold combination core milling slot.

c. Medium depth shell parts. The concave mold is drilled at an equal distance from the cavity, and the convex mold is drilled with an oblique hole to obtain a circuit similar to the shape of the part.

d. Deep cavity products. The convex and concave molds are of combined type, and the cooling is done by turning the spiral groove, and the water is fed from the center and cooled at the end (at the gate) and then flows out of the mold in sequence along the spiral water channel that surrounds the molded part.

6. Cooling water channel should be easy to process and assemble. Cooling water channel structure design must pay attention to its processing technology, to be easy to process manufacturing, as far as possible using simple processing technology such as drilling.

For the combination of mounting cooling water channel also pay attention to water sealing, to prevent cooling water leakage into the cavity caused by cavity corrosion.

Summary

Injection molding cooling systems help regulate the temperature of the molten plastic, as well as the mold itself. This helps prevent defects in the finished product and ensures consistent quality. In addition, the cooling system helps to reduce production time and increase productivity.

Many details of injection molding mold design have a great impact on the quality and production cycle of injection molded products. If you have a project for injection molding process that needs to be done, Zetarmold is a good choice, and our team of experienced mold design engineers will help you pay attention to and solve all the details.

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