How to choose a suitable Dalian plastic blown film machine for oneself?

As an important equipment in the plastic processing industry, the plastic blown film machine has continuously improved its technical level and application scope. With the increasing demand for high-performance and environmentally friendly films in the market, the development prospects of blown film machines are broad. In the future, through technological innovation and industrial upgrading, plastic blown film machines will play an important role in more fields, contributing to economic development and environmental protection.

Dry polyethylene particles are added to the hopper and enter the screw by the weight of the particles themselves. The rotating inclined surface generates a thrust perpendicular to the inclined surface of the plastic, pushing the plastic particles forward. During the pushing process, due to the friction between the plastic and the screw, the plastic and the barrel, as well as the collision friction between particles, and the external heating of the barrel, the plastic gradually dissolves. The molten plastic is filtered by the machine head to remove impurities and comes out of the mold mouth. It is cooled by an air ring, inflated by a herringbone plate, pulled by a roller, and rolled into a cylinder to form the finished film.

How to choose a suitable Dalian plastic blown film machine for oneself?

1、 Clarify production requirements

1. Type of raw materials

Common raw materials: PE (polyethylene), PP (polypropylene), PVC (polyvinyl chloride), POF (polyolefin heat shrink film), PA (nylon), etc. Different raw materials correspond to different types of blown film machines (such as PE blown film machines, PP blown film machines, etc.), and the matching model should be selected according to the target product.

Attention points:

The melting temperature and flowability of raw materials vary greatly, and it is necessary to confirm whether the temperature control system and screw design of the equipment are suitable (for example, PE materials usually require a screw length to diameter ratio of 25:1-30:1, and PVC materials require dedicated screws to prevent degradation).

If multiple raw materials are involved, multi-functional compatible models or multi-layer co extrusion equipment (such as three-layer co extrusion that is compatible with different material composites) can be considered.

2. Application and specifications of film

Purpose oriented:

Packaging field: Food bags and cling films require high transparency and hygiene standards, and can be equipped with PE or POF blown film machines, matched with models suitable for purification workshops.

Agriculture: mulching film and greenhouse film need anti-aging and heat preservation, and PE film blowing machine+anti-aging additive function can be selected.

In the industrial field, stretch film and wrapping film require high tensile strength, and LLDPE special blown film machines or multi-layer co extrusion equipment can be selected to enhance performance.

Specification parameters:

Width: Select the "bubble diameter" range of the blown film machine based on the width of the finished film (if the target film width is 1 meter, the equipment needs to have a maximum blown bubble diameter of ≥ 1.2 meters).

Thickness: Single layer film thickness range (such as 0.01~0.1mm), multi-layer film needs to confirm the thickness control accuracy of each layer (high-precision equipment error ≤ ± 3%).

Production: Calculate the hourly extrusion rate of the equipment based on daily/monthly production demand (if the target daily production is 5 tons, the equipment production capacity needs to be ≥ 200kg/h).

2、 Pay attention to device performance and configuration

1. Selection of core components

Screw and barrel:

Length to diameter ratio (L/D): The larger the length to diameter ratio, the better the plasticizing effect, suitable for high viscosity raw materials (such as PVC requiring L/D=18-22, PE/PP commonly using L/D=25-30).

Material: It needs to be wear-resistant and corrosion-resistant (such as 38CrMoAlA nitride steel). If producing raw materials containing fillers, double alloy screws (such as tungsten carbide coating on the screw core) can be selected.

Mold head structure:

Single layer die: suitable for a single material, with low cost (such as spiral die having better discharge uniformity than plate die).

Multi layer co extrusion die: It is necessary to confirm whether the channel design avoids material mixing (such as independent channels+stacked composite structures), and the higher the number of layers, the higher the price (the cost of three-layer co extrusion is 30%~50% higher than that of single-layer).

Cooling system:

Wind ring: Choose a dual air outlet wind ring with adjustable air volume, which has high cooling efficiency (such as a Φ 1200mm wind ring suitable for membrane bubble diameters of 800~1200mm).

Water cooled auxiliary equipment: During high-speed production (such as film blowing speed>80m/min), it is necessary to use water cooled rollers to avoid overheating and deformation of the film.

2. Automation function

Temperature control system:

An intelligent PID temperature controller (with an accuracy of ± 1 ℃) is required, with multi-stage zone temperature control (such as screw three-stage, mold three-stage, and air ring independent temperature control), to ensure uniform plasticization of raw materials.

Traction and winding:

Automatic tension control: driven by magnetic powder brake or vector variable frequency motor, to avoid film stretching deformation (tension fluctuation ≤± 5N).

Automatic correction: Electric eye tracking of edges, pneumatic or servo correction (correction accuracy ± 1mm), suitable for high-speed production.

Dual station winding: No need to stop and change the winding, improving efficiency (such as winding diameter ≥ 600mm, supporting surface winding and center winding switching).

Other functions:

Online detection: Thickness scanners (such as beta ray thickness gauges) monitor the uniformity of the film in real time, paired with automatic adjustment of the air ring or traction speed.

Automatic feeding and drying: suitable for moisture absorbing raw materials (such as PA nylon that needs to be dried to a moisture content<0.1%), optional vacuum feeding+drying machine integrated machine.

3、 Consider production efficiency and cost

1. Capacity matching

Theoretical Capacity Calculation:

Capacity (kg/h)=screw diameter ² x aspect ratio x rotational speed x raw material density x filling coefficient (empirical value: Φ 65mm screw @ 25:1 aspect ratio, PE material capacity is about 80-120kg/h).

Actual efficiency:

It is necessary to consider the time required for material replacement, mold replacement, and maintenance (such as cleaning the flow channel for multi-layer co extrusion material replacement, with a single time consumption of ≥ 2 hours). It is recommended to choose a quick change mold head (such as a hydraulic screen changer, with a screen replacement time of<5 minutes).

2. Energy consumption control

Motor power: Under the same production capacity, choose high-efficiency and energy-saving motors (such as servo motors that save 30% electricity compared to ordinary motors) to reduce long-term electricity costs.

Heating power: Ceramic heating coils are 20% more energy-efficient than traditional resistance heating coils, and have a faster heating rate (such as mold heating power: 1-1.5 kW per centimeter diameter).

3. Initial investment and later maintenance

Price range:

Single layer mini machine (Φ 45mm screw): 50000 to 150000 yuan, suitable for small workshops.

Three layer co extrusion medium-sized machine (Φ 90mm screw): 500000 to 1 million yuan, suitable for small and medium-sized enterprises.

Five layer co extrusion large machine (Φ 120mm screw): 2 million to 5 million yuan, suitable for large-scale production.

Maintenance cost:

Universality of accessories: Choose mainstream brands (such as Jinming Precision Machinery and blown film king) to avoid difficulties in repairing non-standard parts (such as screws and mold heads that need to be customized by the original factory).

Wear life of vulnerable parts: The air ring nozzle, traction roller adhesive layer, etc. need to be replaced regularly. Please inquire with the supplier about the price and supply cycle of the accessories.

The extruder is the core component of the blown film machine, mainly composed of screws, barrels, and heaters. Its function is to heat, melt and evenly extrude plastic particles. The mold head is a key component for thin film forming, usually with a circular structure. Molten plastic is extruded through a die to form a tubular film. The cooling system includes a cooling air ring and a cooling water ring, which are used to quickly cool the film bubbles and shape them.

The multi-layer co extrusion blown film machine can co extrude various plastic materials with different characteristics together to form a multi-layer structure film, which has better physical and chemical properties such as barrier properties, flexibility, strength, etc. Common types include three-layer co extrusion blown film machines, five layer co extrusion blown film machines, etc., which are widely used in high-end food packaging, pharmaceutical packaging, cosmetics packaging and other fields.