First, the plastic mixture is put into molds (Figure II.2-1a)
Gas not immediately pumped into that after a lapse of time (very short, khoangvai seconds) to be inserted (Figure II.2 1B). This delay in order to establish lieuran external physical layer product called the crust. Coating thickness depends on the time delay, short delay Thoigian make thin crust thickness than desired. The thickness of the coating also depends on the volume of the liquid mixture in the cavity. The task of preventing the crust is riddled product khixuyen pressure.
Air pressure gradually increased (Figure II.2-1c), airflow tend to go to places where there canthap force (the edges of the mold) for dinner pros fill process makes blown plastic mixture to the mold DIXA, product crust is formed with gradually increasing thickness.
Finally, holding phase (Figure II.2-1d), the mixture filled in mold under pressure of the gas, Khingan prevent the formation of dimples on the surface of the product and the thickness of the crust reaches the end, it comes with the cooling process.
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