5. Injection Machine Tips on Precision Plastic Injection OEM
Precision injection molding machine is necessary to start precision plastic injection OEM with the following requirements:
5.1 High injection power
Precision injection molding machines generally use larger injection power to meet the high-pressure, high-speed injection conditions, so that the range of dimensional deviation of the product is reduced and dimensional stability is improved.
5.2 High precision control
5.2.1 Guaranteed repeatability of injection molding process parameters
The precision injection molding machine implements multi-stage feedback control for process parameters such as:
injection volume, injection pressure, holding pressure, pre-molding pressure, injection speed and screw speed.
while the temperature of the barrel and nozzle is controlled by PID (Proportional Integral Derivative), which makes the temperature control accuracy at +/- 0.5°C, thus ensuring the stability and reproducibility of these process parameters and avoiding the products accuracy being affected by changes in the process parameters.
5.2.2 Mold temperature control
Mold temperature affects the products accuracy, especially for crystalline plastics.
The precision injection molding machine enhances the control of product shaping during the cooling stage in the mold cavity and the control of ambient temperature when the product is demolded from the mold.
5.2.3 Clamping force control
Clamping force affects the products accuracy.
If the clamping force is too small, the product will have an overflowing edge under high pressure, which will affect the accuracy; while if the clamping force is too large, the product will be deformed by the mold and affect the accuracy during plastic injection OEM
5.2.4 Oil temperature control in hydraulic systems
Changes in oil temperature can cause changes in hydraulic oil viscosity and flow rate, resulting in fluctuations in injection process parameters, which can affect product accuracy.
The hydraulic oil is controlled by closed loop heating and cooling to stabilize the oil temperature at 50~55°C.
5.3 Fast response time of hydraulic system
Plastic molding supplier is usually with high pressure and high speed injection process.
Since the transition between high and low pressure and high and low speed is fast, the hydraulic system is required to have a fast response speed to meet the needs of the precision injection molding process.
For this reason, hydraulic components with high sensitivity and fast response time were used in the hydraulic system, and proportional cartridge technology was adopted.
When designing the oil circuit, the flow from the control element to the actuating element was shortened.
In addition, accumulators are used to improve the hydraulic system’s response speed and absorb vibration and stabilize pressure. With the application of computer control technology on precision injection molding machines, the entire hydraulic system works under low noise, stable, sensitive and precise conditions.
plastic molding manufacturer should recognize this when you use oil hydraulic system.
5.4 Good rigidity of clamping system
The injection pressure of precision injection molding machine develops in the direction of high pressure and ultra-high pressure to reduce the shrinkage rate of products and increase the density of products; the injection speed develops in the direction of high speed to meet the injection molding requirements of products with complex shapes.
Therefore, the mold closing system should have enough rigidity to avoid deformation during the plastic injection OEM process and affect the accuracy of the products. The structure parts of the mold clamping system, such as moving and fixed mold plates, tie rods and clamping mechanism, should be carefully designed and selected to improve rigidity.