What Is The Process Of Three-layer Blown Film?

The process of three-layer film blowing machine is a complicated one, involving the processing, extrusion, blow molding, cooling, molding, stretching, winding, etc.. Here are the details:
1.Preparation and mixing of raw materials
Raw Material Selection: Choose suitable plastic materials such as LDPE, LDPE, HDPE, etc., according to product requirements. These ingredients usually exist in the form of particles.
Raw material mixing: Different types of plastic particles are mixed proportionally according to the performance of the product. In the stirring process, the uniformity of raw materials should be ensured to avoid color difference or uneven performance.
Drying treatment: Dry mixed raw materials, remove moisture from them, prevent air bubbles from forming during extrusion, and affect product quality.
2.Extrusion molding
Heating and melting: Add dry ingredients to the extruder gradually melt and transport the ingredients forward by heating and rotating the screw. The extruder is generally divided into three segments: feeding section, compression section and metering section. The temperature of each section and the speed of the screw must be strictly controlled.
Tripleextrusion: Triple blower equipped with three independent extruders, responsible for extrusion of the plastic melt inside, middle and outer layers. Three types of melt converge at the end of the die to form a three-layer film through a special flow design.
Die head molding: Extrusion of the plastic inside the die head, forming cylindrical film bubble. The structure of die head has important influence on the thickness, uniformity and appearance quality of the film.
3.Blowing and cooling
Blown air: Compressed air is introduced into a film bubble extruded from the mold and blown to the required diameter. The airing ratio (the ratio of film bubble diameter to die head diameter) is one of the important parameters that affect membrane performance.
Cooling and molding: The blown film bubble is cooled by an air ring to solidify and stabilize its shape. In order to ensure the cooling effect and surface quality of the film, the wind volume, wind speed and temperature of the film must be controlled accurately.
4. Drag and twist
Traction: The cooled film moves forward at a constant speed through the herringbone plate and a traction roller. Tension and tension need to be precisely controlled to prevent the film from stretching or sagging.
Trim: During the film pulling process, the edges of the film may need to be trimmed to eliminate irregularities and ensure that the width of the film meets requirements.
Reel: Reel film is sucked into a reel through a reel machine. When winding, the film must remain flat and the tension must be uniform to avoid wrinkling or uneven loosening.
V. Quality Inspection and Packaging
Quality Inspection: quality inspection of rolled film thickness, width, appearance quality, physical properties, etc. to ensure that the product meets relevant standards and customer requirements.
Packaging: Qualified films are usually packaged in cardboard boxes or plastic sheeting to prevent damage during transport and storage.