What parameters should be considered when purchasing a PE blown film machine?

When choosing a PE blown film machine, the following key parameters and performance indicators should be comprehensively considered to match production needs and ensure equipment stability and efficiency:

1、 Basic specification parameters

1. Applicable raw material types

Core requirement: Clearly define the processing materials (such as LDPE, LLDPE, HDPE, or recycled materials), with significant differences in melt index, viscosity, and processing temperature among different materials.

Focus points:

The material of the screw and barrel needs to be wear-resistant (such as nitride steel or double alloy material), especially suitable for high proportion recycled material scenarios.

The precision of the temperature control system needs to match the requirements of the raw materials (such as LDPE processing temperature of about 160-190 ℃, LLDPE processing temperature of about 170-210 ℃).

2. Product specification range

Film width: Determine the blown film width (such as 500-2000mm) based on the target product, paying attention to the adjustable range of the mold head and the width of the traction roller.

Film thickness: The equipment needs to support the target thickness range (such as 0.008-0.15mm) and confirm the ability to control thickness uniformity (with an error of ≤± 3% being optimal).

Production demand: Estimate production capacity through screw diameter and aspect ratio (L/D), for example:

The equipment with a screw diameter of Φ 65mm and L/D=30 has a production capacity of approximately 80-120kg/h (LDPE).

2、 Core performance parameters

1. Screw and barrel design

Screw diameter: The larger the diameter, the higher the extrusion volume (commonly ranging from 50 to 120mm), which needs to be matched with production capacity requirements.

Length to diameter ratio (L/D):

Conventional L/D=28-33, high aspect ratio (such as 35) is suitable for difficult to plasticize raw materials (such as HDPE) to improve plasticization uniformity.

Low aspect ratio (such as 25) is suitable for high filling or recycled materials to reduce degradation caused by shear heat.

Compression ratio: usually 3-5, which needs to be adjusted according to the density of the raw material (such as HDPE compression ratio slightly higher than LDPE).

2. Mold head structure

Type selection:

Core rod die: suitable for blowing low-density films, low cost but prone to weld marks.

Spiral die head: uniform distribution of melt, high film strength, suitable for high-speed production and wide film width.

Multi layer co extrusion die: used for producing composite films (such as three-layer structures), it is necessary to confirm whether the number of layers and flow channel design meet the process requirements.

Mold head diameter: determines the film to large inflation ratio (inflation ratio=film bending diameter × 2/mold head diameter), usually recommended to have an inflation ratio of 1.5-3.0.

3. Traction and winding system

Traction speed: The maximum traction speed needs to match the extrusion volume, and high-speed models (such as 300m/min or more) are suitable for thin film production.

Traction roller configuration:

The material of the upper and lower rollers (such as anti slip silicone rollers) and surface treatment (roughness affects the smoothness of the film).

Roller diameter (such as Φ 150- Φ 300mm), large diameter rollers can reduce film stretching deformation.

Roll up method:

Surface winding: suitable for thin films, high tension control requirements.

Central winding: suitable for thick film or high-speed winding, requiring automatic winding device to improve efficiency.

3、 Auxiliary functions and configurations

1. Temperature control and heating system

Partition temperature control points: The mold head and material barrel need at least 3-5 temperature control zones, and precision models can reach 8-10 zones to ensure accurate temperature gradient.

Heating power: Calculated based on the diameter of the screw (such as a heating power of approximately 12-15kW for a Φ 65mm screw), it needs to match the plasticization requirements of the raw materials.

Cooling system:

Wind ring types (single outlet, double outlet): Double outlet wind rings have higher cooling efficiency and are suitable for high-speed production.

Fan power: It is necessary to ensure sufficient air volume (such as 15-30kW) and be equipped with a wind pressure regulating device.

2. Automation and Control

Control system:

Standard PLC+touch screen, high-end models can be equipped with intelligent temperature control module (such as PID self-tuning) and remote monitoring function.

Must have parameter memory function (storing ≥ 10 sets of process formulas) to facilitate product switching.

Online detection:

Automatic thickness detection (such as beta ray thickness gauge): Real time feedback of thickness data and linkage adjustment of mold head or traction speed.

Correction device: Ensure that the film is wound neatly with an error of ≤± 2mm.

3. Energy consumption and environmental protection

Motor energy efficiency: Permanent magnet synchronous motors or energy-saving deceleration motors are preferred, with energy consumption 20% -30% lower than ordinary motors.

Heating method: Electromagnetic heating or infrared heating has a more significant energy-saving effect (about 30%) compared to traditional resistance heating.

Noise control: The overall noise level is ≤ 85dB, and attention should be paid to the sound insulation design of the fan and reducer.

4、 Other key considerations

1. Manufacturers and services

Industry experience: Priority should be given to manufacturers who have been specializing in the manufacturing of PE blown film machines for more than 5 years, especially considering their cases in the field of target raw materials (such as recycled materials).

After sales support: Confirm whether installation, debugging, operation training, and regular maintenance services are provided, as well as the supply cycle of accessories (such as inventory of vulnerable parts).

2. Cost and cost-effectiveness

Initial investment: Among equipment of the same specifications, spiral die models are 20% -30% more expensive than core rod models, but have higher long-term production efficiency.

Maintenance cost: The lifespan of double alloy screws is 2-3 times that of ordinary nitride steel, and although the procurement cost is high, the replacement cycle is long.

3. Expand compatibility

Reserve upgrade interfaces (such as adding co extrusion layers and online printing devices in the future) to ensure that the equipment can adapt to product line expansion.

Summary and Suggestions

When making a purchase, the core should be "raw material compatibility+production capacity matching+precision control". First, clarify the production goals (such as film usage, thickness, and output), and then compare the screw design, die structure, and automation configuration of different models. For beginners or small and medium-sized enterprises, priority should be given to choosing the standard spiral die head L/D=30、 Models with automatic correction and basic temperature control, balancing performance and cost; If producing high demand films (such as food grade and high-strength packaging films), it is necessary to focus on the cleanliness of the equipment (die design without dead corners), temperature control accuracy (± 1 ℃), and online detection function.