How should the extrusion blow molding process for HDPE barrels be controlled?

How should the extrusion blow molding process for PC water bottles be controlled?

 ① Extruded blow-molded HDPE drums: For extrusion blow molding, HDPE with a melt flow rate (MFR) of 0.25–0.35 g/10 min should be selected. An MFR that is too low makes forming and processing difficult; an MFR that is too high may cause sagging of the mold. Typically, hollow-grade resin is used. 

 ② The barrel temperature for extruding the parison should be controlled between 150 and 210°C. Use the lowest possible processing temperature while ensuring a smooth extruded parison. 

 ③ To ensure the parison adheres closely to the mold cavity wall and achieves the desired product shape, the blow molding pressure is typically maintained between 0.5 and 0.65 MPa. For larger-volume containers with thinner walls or resins with lower melt flow rates (MFR), a higher blow pressure is required; conversely, a lower pressure is sufficient for smaller or thicker-walled containers and resins with higher MFR. 

 ④ The typical blow-up ratio for HDPE drums ranges between 1.5 and 3.0. For larger containers with thinner walls, a smaller blow-up ratio is selected; conversely, a higher blow-up ratio is required. 

 ⑤ The mold temperature for blow molding is 20°C, and the blow pressure is 0.6 MPa.