The way the mold selects the chiller

Chiller is important for mold.In fact, a mold is a heat exchanger. The heat is first transferred from the molten plastic to the mold, and then from the mold to the continuously circulating cooling medium-ice water.

Only a small part of it enters the air and the pressure of the injection molding machine. template. As we all know, a considerable part of the plastic molding cycle is used for cooling, and sometimes it can account for more than 80% of the plastic molding cycle. Therefore, it is necessary to control the cooling time appropriately.

The mold uses a chiller to cool down faster and more efficiently than a cooling tower:

For example, the molding cycle of a mold is generally 20 seconds. If the water in the original cooling tower is replaced with ice water produced by a chiller, it can be shortened to 16 seconds. Although the initial cost of the chiller is higher, it can increase the output by 20%, which can make a big profit in the long-term production. So how to choose the energy of ice water?

From the above we can know that it is related to the specific heat of the molding material, the temperature of the melt, the weight and the temperature of the product when it is demolded.

How to choose a chiller for the mold:

The formula for calculating the ice water energy required by a mold is: Q=W×C×△T×S

In the formula: Q is the required ice water energy kcal/h;

W is the weight of plastic raw materials kg/h;　　C is the specific heat of plastic raw materials kcal/kg℃;

△T is the temperature difference ℃ between the melt temperature and the product demolding temperature;

S is a safety factor (usually 1.35-2.0). When a single machine is matched, a small value is generally selected, and a large value is used when a chiller is matched with multiple molds. For example, when an air-cooled chiller is selected, S should also be selected. Choose a larger one appropriately.

For example: a mold to produce PP products, the output is about 50kg per hour, what is the cooling requirement? What size chiller should be equipped? Q=50×0.48×200×1.35=6480(kcal/h);

6480kcal/h cooling capacity is required per hour. It is difficult to obtain relatively complete data in the process of using PR chiller. According to our previous years of planning and supporting sales experience, △T=200℃, which is an average value of many commonly used products after years of statistics.

If there is a hot glue lane attached to the mold, the energy of the hot glue lane should also be added to the calculation of the cooling capacity. Generally, the hot glue lane is in KW. The unit should be converted into kcal/h, 1KW=860kcal/h.

If the water supply to the factory is sufficient, the temperature is low, and the cost is low, then there is no need to use a chiller, which is generally not realistic, unless the factory can be located near a large lake with a lower water temperature; another It is to use urban deep well water supply to meet the temperature and flow needs, but the cost is often too high. This method can be used for experimental devices, but it is impractical for factories to do so.

Mold chillers are air-cooled, water-cooled, etc. If your company has a cooling tower, it is recommended to use water-cooled mold chillers, which can save costs

To

Setting of temperature difference between ice and water of mold chiller:

The temperature of the mold cooling fluid (ice water) generally changes greatly due to the processing material and the shape of the product. For example, in a thin-walled polyethylene beaker, the mold requires the temperature of the ice water to be below 0°C.

In most other cases, the temperature of the cold water of the chiller required by the mold must be above 5°C. The microcomputer full-featured chiller can provide ice water above 5°C, and the low-temperature intelligent temperature control chiller can meet the requirements below 5°C. And to the requirements below 0°C.

The temperature difference of the ice water at the entrance and exit of the mold is often set according to the requirements of the product. In many cases, the temperature difference is 3-5℃ is ideal, but sometimes the temperature difference is 1-2℃.

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