Comparison of three film forming processes of casting, extrusion and blow molding

There are many plastic film forming methods, among which three processes of casting, extrusion and blow molding are common. The three kinds of process membranes have their own characteristics. This paper mainly analyzes the two aspects of process principle and application field.
Process principle comparison
Casting film
It is a non-stretched, non-oriented flat extruded film produced by melt flow quenching. There is no obvious orientation structure.
Extrusion film formation
Common ones are uniaxial stretching and biaxial stretching, and biaxial stretching is a production method of considerable interest in recent years. The basic principle of the biaxial stretching technology is that the high polymer raw material is first heated and melted into a thick sheet by an extruder, and then is subjected to a certain temperature range below the melting point above the glass transition temperature, and is then carried out in the longitudinal direction and the transverse direction by a stretching machine. The stretching of the multiples causes the molecular chains to be oriented and arranged in an order parallel to the plane of the film, and then heat-set in a tensioned state to fix the oriented macromolecular structure, and finally to form a film by cooling and subsequent treatment.
Blow molding
It is usually manufactured by extrusion blow molding, plasticizing and extruding materials, forming tube blank inflation molding, and then cooling, drawing and coiling. The blown film is oriented.
Different from the above three processes, the conductivity of the film is significantly different; while the stretched film has higher barrier properties than the unstretched film, lower permeability to gas, and improved optical properties, transparency and surface gloss. The dimensional temperature is good, and the thickness is uniform.
Application area comparison
Take CPP, BOPP and ordinary PP film as examples for comparison
CPP
The product has the characteristics of transparency, softness, barrier property and mechanical adaptability. It is resistant to high temperature cooking (cooking temperature above 120 °C) and low temperature heat sealing (heat sealing temperature is less than 125 °C). It is mainly used as an inner layer substrate for composite packaging of food, candy, native products, cooked foods (suitable for sterilization packaging), frozen products, seasonings, soups, etc., which can extend the shelf life of food and increase the aesthetics. It can also be used for the surface layer and compartment of stationery products, as well as auxiliary films, such as photo sheets and labels for photos and collections.
BOPP
Excellent printing performance, can be combined with paper, PET and other substrates, with high definition and gloss, excellent ink absorption and coating adhesion, high tensile strength, excellent grease barrier properties, low electrostatic properties Wait. It is widely used in the field of printing and compounding, and as a packaging material in tobacco and other aspects.
Ordinary PP
Due to the simple process and low cost, the optical performance is slightly lower than CPP and BOPP. Mainly used for the outer packaging of snacks, bread, textiles, folders, record covers, sports shoes, etc.
Among them, BOPP and CPP have improved composite performance and wider application. After compounding, they have moisture-proof, transparent and stiff, and can be used for packaging of dry foods such as peanuts, fast food, chocolate, and cakes. In recent years, the types and types of plastic films in China have gradually increased, and each has its own strengths. With the continuous improvement of technical processes, the packaging film has broad prospects.

Precision Parts By Five-axis Machining

Precision parts are critical components of various products and machines that require precision and accuracy. The five-axis machining technology has revolutionized precision manufacturing by enabling the production of complex geometries with unparalleled accuracy.


Five-axis machining involves the use of a computer numerical control (CNC) machine that has five axes of motion – X, Y, Z, and two rotational axes. This advanced technology allows the machine to produce intricate and complicated parts with high precision and accuracy. Unlike 3-axis or even 4-axis machining, the five-axis machine can rotate and tilt the tool to machine parts from different angles, providing greater flexibility in terms of geometry and design.


Precision parts made using five-axis machining technology are popular in various applications, including aerospace, medical equipment, automotive, and electronics industry. These parts are designed to meet the most stringent standards, making them reliable and durable. The five-axis machine can achieve tolerances as low as 0.0001 inches, providing superior precision that is unmatched by manual machining.


One significant advantage of using five-axis machining technology is increased efficiency. The five-axis machine can perform multiple operations in a single cycle, reducing the time required to produce a part. It can handle complex designs with ease and produce highly accurate parts, making it ideal for applications that require high precision and accuracy.


Another advantage of five-axis machining is increased design flexibility. It allows designers to create highly complex geometries that were not possible with traditional machining methods. With five-axis machining, it is possible to manufacture parts with undercuts, curved surfaces, and geometries that are difficult to access using other machining processes.


In summary, precision parts made using five-axis machining technology offer superior precision, accuracy, and design flexibility. These parts are widely used in various industries, and their high precision and accuracy make them highly reliable in critical applications. As manufacturing technology continues to advance, we can expect more sophisticated techniques that will offer even greater precision and accuracy.

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