1、 Select the appropriate mold temperature controller:
Random selection of mold temperature controllers and DC high-voltage generators can cause a loss of 20% of profits at any time. Therefore, when purchasing, we must carefully consider production needs and strictly review the capabilities of mold temperature controllers before making a decision. Unfortunately, people often overlook this extremely important aspect of injection molding technology, often waking up when there are issues with productivity and quality.
2、 When selecting a mold temperature controller, the following points are the main considerations:
1. Pump size and capacity.
2. Size of internal throat.
3. Heating capacity.
4. Cooling capacity.
5. Control form.
3、 Learn how to calculate:
A. Pump size:
From the known heat dissipation required per cycle, we can easily calculate the required volumetric flow rate of the coolant, and then obtain the required correct cooling capacity. Most manufacturers of mold temperature controllers, DC high-pressure generators, provide formulas to calculate the lowest pump flow rate. Table 4.1 is useful when selecting pumps, as it accurately lists the heat dissipation capabilities of different plastics. The following rule of thumb determines the minimum flow rate required for a pump: If the temperature difference across the mold cavity surface is 5 ℃, the temperature difference is 0.75 gal/min/kW @ 5 ℃ or 151/min/kW @ 5 ℃. If the temperature difference across the surface of the mold cavity is 1 ℃, the minimum required flow rate needs to be multiplied by five times in proportion to be 3.75 gal/min/kW or 17.031/min/kW. In order to achieve stability in product quality, many injection molding companies should control the temperature difference on the surface of the mold cavity at 1-2 ℃. However, in fact, many injection molding manufacturers may not know the importance of this temperature difference or believe that the optimal range of temperature difference is 5-8 ℃. To calculate the required volumetric flow rate of coolant, the following procedure should be used:
First, calculate the amount of heat to be dissipated by planting a plastic/mold combination: If the aforementioned PC cup mold is taken as an example, the actual amount of heat to be dissipated is:
Gross weight of the first mock examination (g)/cooling time (s) ＝ 208/12 ＝ 17.333g/s
The heat dissipation rate of a PC is=368J/g or 368kJ/kg
So the heat required to dissipate per cycle=368 × 17.33/1,000＝6.377kW 。  2. Recalculate the volumetric flow rate required for cooling: According to the above rule of thumb, if the temperature difference on the mold surface is 5 ℃, the flow rate=6.377 × 0.75=4.78 gal/min or=6.377 × 3.41=21.751/min If the mold cavity exhibits a temperature difference of 1 ℃, the flow rate=4.78 × 5=23.9 gal/min or=21.75 × 5=108.731/min 。  3. Regulation of pump flow rate: In order to obtain good heat dissipation effect, the flow rate capacity of the pump should be at least 10% greater than the calculated result, so it is necessary to use a pump of 27 gal/min or 120/min. 4. Pump pressure regulation: Generally, the operating pressure of the mold temperature controller is 2-5 bar (29-72.5 psi). Due to insufficient pressure, it will affect the volumetric flow rate of the coolant (pressure loss due to flow resistance), so the higher the pump pressure, the more stable the flow rate. For molds with very small cooling pipes (for example, the pipe diameter is 6mm/0.236in), the pump pressure needs to be 10bar (145psi) to provide sufficient heat dissipation speed (i.e., coolant speed). In general, the higher the volumetric liquid velocity requirement of the coolant, the smaller the diameter of the pipe, the greater the required pump output pressure. Therefore, in general applications, the pressure of the mold temperature controller should exceed 3 bar (43.5 psi)
B. Heating capacity:
The heating capacity required to heat a 500kg mold to 50 ℃ is 3kWh.
2. The specific heat capacity required to raise a mold weighing 700 kg to 65 ℃ is 6.5 kW/hr. In general, the stronger the heating capacity, the less heating time required (doubling the heating capacity, reducing the heating time). This article provides a very useful information for injection molding manufacturers, which can immediately find out the heating requirements of any mold, thereby obtaining the heating capacity of the correct mold temperature controller. It is often because the ability of the mold temperature controller is too low that the mold cannot reach the optimal temperature state. To know the actual performance of the mold temperature controller, we can compare its actual and calculated mold heating times.
C. Refrigeration capacity:
The design and components of the freezing circuit of the mold temperature controller are extremely important for accurate control of mold temperature. When the temperature of the mold or heating liquid rises to the set value, the mold temperature controller must be able to quickly and effectively prevent the temperature from continuing to rise. The method is to introduce another lower temperature liquid, and the control of its introduction is the responsibility of the electromagnetic valve. Therefore, the elimination and stability of temperature overrides depend on the size of the solenoid valve. The bore diameter of the cooling solenoid valve can be calculated using the following formula: Inlet pump valve
Refrigeration capacity (gal/min)=kW × 3.16/△t     
Here △ t=the difference between the production temperature set by the mold temperature controller and the chilled water temperature:
KW=heat required to be removed from the mold
The following table lists the volumetric flow rates that can be provided by different solenoid valve apertures:
Solenoid valve aperture volume flow rate
in     mm   gal/min  1/min
0.25  6.35   0.7    3.18
0.375  9.53   1.2    5.45
0.500  12.70  3.3    14.98
0.750  19.65  5.4    24.52
1.000  25.40   10.0   45.40
1.250  31.75   13.0   59.02
1.500  38.10   20.0   90.80
After calculating the freezing capacity, the corresponding solenoid valve can be found from the above table, as shown in the following example:
The heat that needs to be removed from the PC cup mold is 6.377 kW
The set temperature for production is 90 ℃
The temperature of chilled water is 18 ℃
△T＝90－18＝72℃     
Therefore, freezing capacity=6.377 × 316/72=0.28gal/min or 1.271/min
From the table above, it can be seen that solenoid valves with a bore diameter of 6.35mm/0.250in can provide sufficient volumetric flow rate, and are suitable for use with a mold temperature control range of ± 1 ℃. The pressure drop in the solenoid valve affects the flow rate. The flow rate values in the above table are based on a pressure drop of 1 bar (14.5 psi). Therefore, the higher the pressure drop, the faster the flow rate of chilled water. The typical pressure drop for a solenoid valve is 2 bar (29 psi).
D. Liquid mold temperature heating control system:
The main purpose of any mold temperature controller is to control the mold temperature within the range of (± 2 ° F). Therefore, the temperature control of the liquid running between the mold pipes must be accurate, otherwise the purpose of mold temperature control cannot be achieved. The control method of some mold temperature controllers is only in the form of ON/OFF, and their working principle is to compare actual and set temperatures. If the actual temperature is much lower than the set temperature, the electric heating will be fully turned on. When the actual temperature reaches the set value, the electric heating will be turned off, resulting in a significant actual positive and negative temperature deviation due to the control of the ON/OFF mode. This temperature change not only directly affects the temperature of the liquid, but also indirectly causes a significant excessive rise and fall in the mold, needless to say, which must ultimately be reflected in the quality of the finished product. Therefore, we should use a heating control system in the form of PID (proportional, integral, differential), which can ensure that the mold temperature control is maintained within the range of ± 1 ℃ (± 2 ° F).
Daheda mold temperature machine, oil temperature machine, injection molding temperature machine, water cooled chiller, air cooled chiller. Open water chiller, screw water chiller, hopper dryer, hot air dryer, plastic dryer, plastic dehumidifier, dehumidifier dryer, oven, industrial oven, cooling tower, cold water tower, horizontal mixer, vertical mixer, plastic mixer, drum mixer, dry powder mixer, high-speed mixer, vertical mixer, screw mixer, dry powder mixer, powder mixer, mixer, color mixer, mixer, Plastic Crusher, Plastic Crusher, Recycled Plastic Crusher, Recycled Plastic Crusher, Strong Crusher, Plastic Crusher, Suction Machine, Pumping Machine, Automatic Suction Machine, Top Suction Suction Machine, Induction Suction Machine, Electric Eye Suction Machine, Small Suction Machine, 300G Suction Machine, 700G Suction Machine, 800G Suction Machine, 5HP Suction Machine, Large Suction Machine, Plastic Vibrating Screen, Vibrating Screen, Vibrating Screen, Machine Side Crusher, Machine side recycling machine, slow crusher, slow crusher, low speed crusher, mold rack, drawer type mold rack, heavy mold rack, central feeding system, cooling tower installation, 6KW mold mixer, 9KW mold warmer, 12KW mold warmer, Shenzhen mold warmer, Dongguan mold warmer, Guangzhou mold warmer. Automatic mold temperature machine, water mold temperature machine, oil mold temperature machine.