Detailed explanation of water quality, temperature difference, flow rate, and pressure for mold specific chillers

        A chiller is an energy-saving machine that achieves cooling effects through steam compression or absorption circulation. The full name of a chiller is a cooling water circulation machine, also known as a refrigerator, chiller, freezer, chiller, ice water machine, small chiller, industrial chiller, refrigeration unit, low-temperature chiller, and laser chiller. Due to their widespread use in various industries, their nicknames are countless depending on the industry. (www.jiashengsz.com)

        Chillers are closely related to the quality of products in the mold industry and are highly valued in terms of quality. The surface finish of the mold must reach level 7 (Ra1.6), similar to the surface produced by cold extrusion or machining, with a metallic luster. The tolerances and smoothness indicated on the drawings all affect the product forming, so suitable chillers should be selected for cooling according to different accuracy requirements during processing.

        There are many mold hardware factories that want to achieve their desired cooling effect, but do not know which machine is more suitable for their production workshop. So now, Shenzhen Jiasheng Plastic Machinery will analyze the selection of mold cooling chillers and the precautions to be taken, hoping to be helpful to friends in the mold industry.

        A mold is a heat exchanger, where heat is transferred from melted plastic to the mold, and then to the continuously circulating cooling medium - ice water. Only a small portion enters the air and the pressure plate of the injection molding machine. As is well known, a considerable portion of the plastic forming cycle is used for cooling, sometimes accounting for over 80% of the plastic forming cycle. Therefore, it is absolutely necessary to control the cooling time to the minimum. For example, the molding cycle of a mold usually takes 20 seconds. If the water from the original cooling tower is replaced with ice water generated by a chiller for cooling, it can be shortened to 16 seconds. Although the initial cost of choosing to equip the chiller was higher, it can increase production by 20% and can achieve significant benefits in long-term production.

        1、 Treatment of water quality of mold cooling chiller.
        The softening of water is also an issue that cannot be ignored in the process of using chillers in the mold industry. The pH value of water also needs to be constantly observed, and the optimal pH value should be equal to 7. A pH value greater than 7 will cause terrifying corrosion phenomena. If no measures are taken, it will scale in the evaporator and mold, which will act as insulation. In severe cases, it will reduce its energy conversion effect by 30%. Obviously, this requires considering the softening of hard water. The most effective method is to configure an electronic hard water softener in the system, which is designed and manufactured based on the principle of ion exchange. Different specifications of softeners can be configured according to different flow rates, directly connected to the circulating water pipeline. Generally, the cost of configuring a water treatment softener is not too high, and a certain proportion of scale remover can be regularly added to the circulating system.

        So, how to choose ice water energy? From above, we can know that it is related to the specific heat of the forming material, the temperature during adhesive melting, the weight, and the temperature during product demolding.

        2、 First, consider the temperature difference of the mold cooling chiller.
        The temperature of the mold cooling fluid (ice water) is generally subject to significant changes in processing materials and product shape, such as polyethylene thin-walled beakers, where the mold requires the ice water temperature to be below 0 ℃; In most other cases, the temperature of the ice water required by the mold is above 5 ℃. The microcomputer fully functional cold water function provides ice water above 5 ℃, and the low-temperature intelligent temperature control cold water function meets the requirements of below 5 ℃ and below 0 ℃.

        The temperature difference between the ice water at the inlet and outlet of the mold is often set according to the product requirements. In many cases, a temperature difference of 3-5 ℃ is the most ideal, but sometimes a temperature difference of 1-2 ℃ is also required. The smaller the temperature difference, the greater the amount of ice water required to carry out the same amount of heat, and vice versa. For example, when the temperature difference is 5 ℃, the flow rate needs to be 60L, while when the temperature difference is 2 ℃, the flow rate needs to be 150L. The ice water flow required for a mold is directly related to the heat that the mold needs to carry away and the temperature difference between the ice water entering and exiting the mold. For example; To remove 6480kcal/h of heat from the mold, if the temperature difference is 3 ℃, what is the minimum required flow rate? Ice water flow rate Q=6480 ÷ 3 ÷ 60=36 (L/min).

        3、 Flow and pressure of mold cooling chiller.
        Generally, for cooling of injection molding molds, the pressure of ice water can be selected from 0.1 to 0.2Mpa to meet the requirements, while the microcomputer fully functional cold water function can meet this requirement. When the pressure requirement is higher than 0.2Mpa, separate planning is needed to use corresponding pressure water pumps to meet the water supply needs of the system.

        Table of the relationship between flow rate and pipe diameter: Pipe diameter 3/8 "1/2" 3/4 "1"/4 "1"/2 "2" 3 "The flow rate requires 6480kcal/h of cooling per hour, and it is difficult to obtain relatively complete data during the process of selecting a PR chiller. Based on our years of planning and sales experience, △ T=200 ℃, which is the average value of many commonly used products after years of statistics. (www.jiashengsz.com)