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What is the role of injection molding machine for holding pressure?
1. The function of holding pressure is to maintain a pressure when it melts and cools/solidifies and shrinks, and continues to inject melting to fill the shrinking space, reducing or avoiding the generation of dents.
The set pressure of the pressure holding section cannot exceed the set pressure of the extrusion section, otherwise burrs may be generated in the pressure holding section. The multi-stage holding pressure drops every stage, and the ideal decline is a linear gradual decline, non-class decline, to meet the actual needs of gradual contraction.
Due to the slow shrinkage, the forward speed of the screw is also slow. For example, a speed of 2% is sufficient. The energy saving of the injection molding machine is mainly to reduce the flow rate of the pump to such as 3% when the pressure is maintained. Compared with the fixed pump whose flow rate is always 100%, it saves 97%. The longer the pressure holding time (large wall thickness), the more power consumption will be saved.
When holding pressure, only the pressure is needed to control the flow rate, because the shrinkage rate is not controlled by the injection molding machine, which is just the opposite of the pre-injection section.
Regarding how long the holding time is, when the production weight no longer rises or the dent is acceptable, the holding pressure can be stopped. The next step is plasticization. It starts at the same time as the cooling time, it is judged that the cavity is filled
2. It can be said that the holding pressure point is the position of the screw that separates injection (including extrusion) and holding pressure. The operator needs to set the pressure holding point, which is to find out the position of the screw when the cavity is filled.
3. Injection molding machine operation
From the operational level, injection and pressure holding have the following similarities.
1. Unless the injection servo valve is used, the injection direction valve is open during injection and pressure maintaining, and will not be closed during the injection (and of course it will not turn).
2. On general computer screens, injection and pressure holding have speed and pressure control.
3. The segment of injection, although the most accurate distinction is based on the position of the screw, it can also be distinguished by time. (called time injection) is the same as the segment of holding pressure
The set pressure of the pressure holding section cannot exceed the set pressure of the extrusion section, otherwise burrs may be generated in the pressure holding section. The multi-stage holding pressure drops every stage, and the ideal decline is a linear gradual decline, non-class decline, to meet the actual needs of gradual contraction.
Due to the slow shrinkage, the forward speed of the screw is also slow. For example, a speed of 2% is sufficient. The energy saving of the injection molding machine is mainly to reduce the flow rate of the pump to such as 3% when the pressure is maintained. Compared with the fixed pump whose flow rate is always 100%, it saves 97%. The longer the pressure holding time (large wall thickness), the more power consumption will be saved.
When holding pressure, only the pressure is needed to control the flow rate, because the shrinkage rate is not controlled by the injection molding machine, which is just the opposite of the pre-injection section.
Regarding how long the holding time is, when the production weight no longer rises or the dent is acceptable, the holding pressure can be stopped. The next step is plasticization. It starts at the same time as the cooling time, it is judged that the cavity is filled
2. It can be said that the holding pressure point is the position of the screw that separates injection (including extrusion) and holding pressure. The operator needs to set the pressure holding point, which is to find out the position of the screw when the cavity is filled.
3. Injection molding machine operation
From the operational level, injection and pressure holding have the following similarities.
1. Unless the injection servo valve is used, the injection direction valve is open during injection and pressure maintaining, and will not be closed during the injection (and of course it will not turn).
2. On general computer screens, injection and pressure holding have speed and pressure control.
3. The segment of injection, although the most accurate distinction is based on the position of the screw, it can also be distinguished by time. (called time injection) is the same as the segment of holding pressure
