1. Process Flow
Cast Film Process: After the plastic resin is heated and melted, it is extruded through a linear die head and directly coated on a cooling roller to quickly cool and form a film.
Blown Film Process: The molten plastic is extruded through a ring die head to form a tubular film, and it is blown into a bubble shape by air, and then rolled up after cooling and shaping in the air.
2. Product Characteristics
Cast Film:
Transparency: Due to rapid cooling, cast film has high transparency and gloss, which is suitable for packaging that needs to display products.
Thickness Uniformity: The thickness is precisely controlled and the uniformity is good.
Mechanical Properties: The longitudinal strength is high, but the transverse strength is relatively low.
Blown film:
Strength and puncture resistance: Due to bidirectional orientation, blown film has high strength and puncture resistance in both the longitudinal and transverse directions, and is suitable for packaging heavy or irregularly shaped items.
Transparency: Due to the slow cooling speed, the transparency and glossiness are slightly inferior to cast film.
Thickness uniformity: There may be a certain thickness deviation, but the overall performance is balanced.
3. Application areas
Cast film: Commonly used for packaging with high requirements for transparency and appearance, such as food packaging, pharmaceutical packaging, etc.
Blown film: Suitable for packaging that requires high strength and puncture resistance, such as industrial packaging, heavy item packaging, etc.
In summary, cast film and blow molding processes each have their own unique advantages and applicable scenarios. The choice of which process should be based on the specific needs of the product, such as transparency, strength and application areas.
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