Silver python machinery will provide you with more valuable advice. Silver python machinery main products are plastic extrusion blow molding machine, product categories are milk bottle blow molding machine, oil drum blow molding machine, chemical barrel blow molding machine and other widely use. Size for 50ML to 120L of hollow plastic.
Points for hdpe barrels as below.
(1) raw material processing. Since PE is a nonpolar polymer, it is generally not hygroscopic, so PE raw material does not have to be dried before blow molding, as long as it is dyed according to the requirements of the product (or with masterbatch) .

(2) barrel temperature. In the case of smooth extrusion of the parison, use a lower processing temperature as much as possible. Excessive temperature will cause the melt strength to decline or parison sagging, resulting in uneven longitudinal wall thickness, and the cooling time lengthened to extend the molding cycle. However, when the temperature is too low, the surface gloss of the product is poor and the internal stress is increased. General HDPE barrel temperature control in the 150-210C.

(3) blow molding pressure. In order to ensure that the parison close to the cavity wall and get the desired shape of the product, blow molding pressure is generally controlled between 0.5-0.65MPa. For bulky, thin barrels of containers and MFR lower resin, blow molding pressure to be higher, otherwise the opposite.

(4) blowing ratio. Generally, the inflation ratio of HDPE drum is between (1.5-3): 1. The container is larger and the bucket wall is thinner to choose a smaller blow ratio than vice versa.