Molding Conditions of Injection Molding Machine (Part 4)

 1. Screw speed


The screw speed in injection molding conditions refers to the speed of the screw used to mix the pellets. The unit is rpm (rev/minute).


If the screw speed is too fast, air may be mixed into the molten resin and gas may be easily generated. If the screw speed is too slow, there may be insufficient mixing and deviations in material quality may occur.


2. Screw back pressure


Screw back pressure refers to the pressure when the screw is retracted during material metering. The unit is MPa or kgf/cm2. The mixing state of the material will change due to the change of back pressure.


3. Mold opening and closing speed


Mold opening and closing speed refers to the mold opening speed and mold closing speed of the mold, the unit is mm/s. Shorter mold opening and closing times are effective in shortening cycle time, but if the mold closing speed is too fast, the risk of violent collision of the mold will increase, so the brake must be applied just before the mold closing is completed.


However, if the mold opening speed is too fast, the demoulding state may change, and the product quality may also change.


4. Clamping force


Clamping force refers to the force to keep the parting surface closed, the unit is kN (kilonewton) or tf (ton f, read as "ton" at the production site, but from a mechanical point of view, the unit of gravity is f correct).


5. Ejection speed


Ejection speed refers to the forward speed of the top module, the unit is mm/s. If the ejection speed is too fast, the molded product may be deformed or the surface may be whitened. If the ejection speed is too slow, the molding cycle will be prolonged.


6. Ejection times


The number of times of ejection can be set within the range of 1 to 3 times. If the mold release is good, only one ejection is enough, but if the mold release is not good, the molded product may take several ejections before it can be removed from the mold.

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