Factors affecting the cooling rate of products in injection molding

1. Plastic product design: mainly the wall thickness of plastic products. The greater the thickness of the product, the longer the cooling time. Generally speaking, the cooling time is proportional to the square of the thickness of the plastic product, or 1.6 times the diameter of the largest runner. That is, doubling the thickness of plastic products, the cooling time increases 4 times. 2.

2. mold material and its cooling method: mold material, including mold core, cavity material and mold frame material has a great influence on the cooling speed. The higher the heat conduction coefficient of mold material, the better the effect of heat transfer from plastic in unit time, and the shorter the cooling time.

3. Cooling water tube configuration: the closer the cooling water tube is to the mold cavity, the larger the diameter of the tube, the more the number, the better the cooling effect and the shorter the cooling time.

4. coolant flow: the greater the flow of cooling water (generally to achieve turbulent flow is better), the better the effect of cooling water to heat convection to take away heat.

5. nature of the coolant: the viscosity of the coolant and heat transfer coefficient will also affect the heat transfer effect of the mold. The lower the viscosity of the coolant, the higher the heat transfer coefficient, the lower the temperature, the better the cooling effect.

6. plastic selection: plastic is a measure of how fast the plastic will conduct heat from a hot place to a cold place. The higher the thermal conductivity of the plastic, the better the thermal conductivity, or the lower the specific heat of the plastic, the easier the temperature change, so the heat is easily dispersed, the better the thermal conductivity, and the shorter the cooling time required.

7. Processing parameters setting: the higher the material temperature, the higher the mold temperature, the lower the ejection temperature, the longer the required cooling time.
 

Design rules of cooling system.

8. the designed cooling channel should ensure the cooling effect is uniform and rapid. The purpose of designing the cooling system is to maintain proper and efficient cooling of the mold. Cooling holes should be of standard size to facilitate machining and assembly. 9.

9. When designing a cooling system, the mold designer must determine the following design parameters based on the wall thickness and volume of the molded part - the location and size of the cooling holes, the length of the holes, the type of holes, the configuration and connection of the holes, and the flow rate and heat transfer properties of the coolant.