Unclear bottle neck threads

During the extrusion '2079851475616104457 production process, the product exhibits the quality defect of "Unclear bottle neck threads". Specifically manifested as blurred bottle neck threads or incomplete filling. This defect is relatively common when processing materials such as HDPE, PP, PVC, and PC, and its occurrence conditions are usually related to unreasonable settings of melt temperature, extrusion speed, blowing air pressure, and mold temperature. When the Unclear bottle neck threads situation is severe, it will cause a series of chain-reaction quality defects in the product in terms of appearance, dimensional accuracy, mechanical properties, etc., which not only reduces the usability and safety of the product, but also directly increases the scrap rate and production cost. Therefore, this problem requires systematic diagnosis and optimization from multiple dimensions, including material selection, the condition of the extruder, die head, die, mold clamping mechanism, and blowing system, as well as melt temperature, extrusion speed, blowing air pressure, and mold temperature.

1. Insufficient venting of the mold thread cavity. The mold is the core tool that imparts shape and surface quality to the product. Unreasonable mold design, such as improper runner/gate dimensions, insufficient venting, inadequate draft angle, etc., will directly cause molding defects. The machining accuracy, surface treatment quality, and daily maintenance condition of the mold also directly affect product quality. 2. Blowing air pressure too low. Pressure directly determines the filling ability of the melt and the mold-contacting effect during the '2079851475616104453. Insufficient pressure results in incomplete filling and poor replication accuracy; excessive pressure may cause secondary defects such as flash and excessive internal stress. The setting of pressure should comprehensively consider factors such as material viscosity, product dimensions, and mold structure. 3. Parison wall thickness too thin at the bottle neck. The uniformity of wall thickness distribution is directly related to the mechanical properties of the product and the consistency of cooling shrinkage. Excessive wall thickness differences will cause inconsistent cooling rates, with sink marks and warpage occurring in thick-walled areas and insufficient strength in thin-walled areas. Wall thickness design should follow the principle of uniform wall thickness, and wall thickness changes should transition smoothly. In terms of equipment maintenance, inadequate regular overhaul and accuracy confirmation of the extruder, die head, die, mold clamping mechanism, and blowing system cause the actual operating parameters of the equipment to deviate from the process requirements, which can also become a potential inducement of the Unclear bottle neck threads problem.

1. Add thread venting structures. The installation of equipment or accessories should strictly follow the installation manual; the key mating surfaces must be cleaned and checked for damage before installation. Fastening bolts should be tightened evenly according to the specified torque values and diagonal sequence; after installation, use precision measuring tools to verify whether the installation accuracy meets the technical requirements. 2. Increase the blowing air pressure. When implementing adjustments, it is recommended to adopt the single-factor variable method, adjusting only one parameter at a time and fully evaluating the effect, to avoid multiple parameters changing simultaneously making the cause of the problem untraceable. The adjustment magnitude should be small rather than large; each adjustment is recommended to be controlled within 5%~10% of the original value, and after adjustment, run stably for at least 3~5 mold cycles to observe the effect. 3. Increase the parison wall thickness at the bottle neck. When implementing adjustments, it is recommended to adopt the single-factor variable method, adjusting only one parameter at a time and fully evaluating the effect, to avoid multiple parameters changing simultaneously making the cause of the problem untraceable. The adjustment magnitude should be small rather than large; each adjustment is recommended to be controlled within 5%~10% of the original value, and after adjustment, run stably for at least 3~5 mold cycles to observe the effect. In terms of material management, incoming inspection of raw materials and in-process inspection of work-in-progress should be strengthened, and the key performance indicators of HDPE, PP, PVC, and PC should be strictly controlled to ensure the stability of molding quality from the source.

In summary, the causes of the "Unclear bottle neck threads" problem can be attributed to the combined action of multiple factors such as insufficient venting of the mold thread cavity and blowing air pressure too low. Solving this problem requires starting from aspects such as add thread venting structures and increase the blowing air pressure, and adopting systematic governance measures. In actual production, it is recommended to establish a prevention and rapid response mechanism for this problem, achieving stable production and continuous improvement through parison wall thickness control and parison temperature uniformity.