In the field of plastic blow molding, the stable operation of the blow molding machine directly determines product quality and production efficiency. As a core control element in the blow molding machine’s extrusion system, precise control of the liquid level is crucial throughout the entire production process. Whether producing everyday plastic bottles, storage tanks for the chemical industry, or plastic components for the automotive industry, the stability of the liquid level is like a “lifeline,” profoundly affecting the wall thickness uniformity, mechanical properties, and appearance quality of the product.

The blow molding machine liquid level line essentially refers to the relatively stable height of the molten plastic surface within the extruder barrel of a blow molding machine. In the extrusion blow molding process, the plastic raw material enters the barrel through the hopper. The shearing action of the screw and the heating action of the barrel gradually melt and plasticize it, forming a melt with a certain viscosity. The liquid level at this point in the barrel is the liquid level, a crucial bridge connecting raw material supply and product formation.

The liquid level plays a key role in two key areas: first, ensuring the stability of the melt supply. A stable liquid level ensures uniform back pressure on the melt during screw rotation, preventing fluctuations in extrusion volume caused by fluctuating melt supply, thereby ensuring the continuity and uniformity of subsequent parison extrusion. Second, it controls the consistency of product quality. If the liquid level is too high, the melt’s residence time in the barrel will increase, potentially leading to excessive melt degradation and compromising the strength and toughness of the product. If the liquid level is too low, the screw may “idle” and inhale air, resulting in defects such as bubbles and uneven wall thickness in the parison, and in severe cases, even causing production interruptions.

In short, as the key link between raw material supply and product formation, the liquid level line of a blow molding machine requires stable and precise control, which is crucial for ensuring product quality and improving production efficiency. In actual production, it is necessary to fully understand the factors that affect liquid level line stability, adopt advanced control technologies, strengthen routine maintenance and management, and continuously optimize process parameters. In the future, with the integration of intelligent and green technologies, liquid level line control of blow molding machines will develop in a more efficient, precise, and environmentally friendly direction, providing strong support for the high-quality development of the plastics blow molding industry.