A blow molding machine is a device used to produce plastic bottles. It heats a plastic preform (bottle preform) and uses high-pressure gas to blow-form it into the desired bottle shape. The entire blow molding process includes the following key steps:
Raw Material Preparation: First, high-quality plastic granules (such as PET, PP, etc.) need to be prepared. These granules will be melted and injection molded into preforms. The quality of the preforms directly affects the performance and appearance of the final bottle.
Preform Heating: The preforms are fed into a heating furnace and softened by infrared heating. The heating temperature is usually controlled between 90-120°C, depending on the type of plastic material and the thickness of the preform.
Blow Molding: The heated preforms are transferred to a blow molding die. High-pressure air (usually 20-40 bar) is injected into the preform, causing it to expand and conform to the inner wall of the die, forming the shape of the bottle. This step requires precise control of air pressure and blow molding time to ensure the uniformity and strength of the bottle.
Cooling and Shaping: After blow molding, the bottle needs to cool and set in the mold. The cooling time is usually 2-5 seconds. Insufficient cooling may cause the bottle to deform, while over-cooling will prolong the production cycle.
Demolding and Trimming: After cooling, the bottles are removed from the mold and trimmed to remove excess flash or burrs. Some high-end blow molding machines are also equipped with automatic trimming functions to improve production efficiency.
Quality Inspection: Finally, the bottles undergo visual inspection or pressure testing to ensure they are defect-free and meet quality standards. Defective bottles are automatically rejected.
