Abstract: A hollow plastic product with a substantially tubular section, two open ends and a thread at the outside of one end of the product is removed from a core mold part by closing the threaded end of the molded product and injecting compressed air into the molded product to loosen the molded product from the core mold part. The threaded end of the product is closed by attaching a closure having a matching thread onto the threaded end.

Abstract: A mold cavity for injection molding a nestable plastic product includes a sidewall section that includes a plurality of primary flow guides for directing injected fluid plastic material into portions of the sidewall section between the primary flow guides, which include narrow mold cavity sections for forming thin sidewall segments of the product and further include secondary flow guides for directing injected fluid plastic material into the narrow mold cavity sections. The sidewall of the product includes a plurality of steps that offset at least some of the thin sidewall segments from one another and the mold cavity includes a corresponding plurality of step sections that offset the narrow mold cavity sections from one another for forming the steps. At least some of the step sections include at least some of the secondary flow guides.

Abstract: During injection molding of a plastic product having a base wall and a sidewall, alignment of the mold parts that shape the mold cavity is maintained by conducting injected plastic material through a sequence of variable-opening throttles in a base-wall-section flow guide of the mold cavity. The openings of the throttles vary in response to variations in the thickness of a region of the sidewall section into which injected plastic material is conducted from the base-wall-section flow guide so that upon an increase in the thickness of such region the openings of the throttles in the base-wall-section flow guide decrease and so that upon a decrease in the thickness of such region the openings of the throttles in the base-wall-section flow guide increase.

Abstract: A suspension is dosed with a coagulant and then with a flocculant and is dewatered to form a thickened sludge or cake and separated liquor, and control of the dewatering performance is improved by adding the flocculant at a predetermined dosage, monitoring the charge in the separated liquor (or monitoring other dewatering parameter of the separated liquor or suspension) and adding coagulant at a dosage selected in response to the monitored charge or other parameter value in order to maintain the value substantially at a preselected optimum value.