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Large Fluctuations in Extrusion Current during Extrusion Hollow Blow Molding

Views: 0     Author: Site Editor     Publish Time: 2023-08-19      Origin: Site

Extrusion hollow blow molding is a widely used manufacturing process for producing hollow plastic containers, such as bottles and containers for various industries. This process involves extruding molten plastic through a die, followed by inflating the hollow preform with compressed air. However, during this intricate process, operators may encounter instances of large fluctuations in extrusion current, which can impact the final product's quality and consistency. 

In this article, we delve into the causes and potential solutions for these fluctuations, aiming to enhance the efficiency and reliability of the extrusion hollow blow molding process.

Causes of Large Fluctuations in Extrusion Current:

1. Inconsistent Material Melting: 

The extrusion process heavily relies on the molten plastic's viscosity and temperature. Any inconsistency in the materials, variations in resin melting, or fluctuations in barrel heating can lead to changes in extrusion current. Inaccurate temperature control could cause the plastic to melt at different rates, resulting in inconsistent flow and fluctuations in extrusion current.

2. Impurities or Moisture Contamination: 

Presence of impurities, such as foaming agents, fillers, or moisture in the plastic resin, can cause irregularities in the extruded material's flow properties. These impurities can disrupt the smooth flow of the molten plastic, affecting the extrusion current.

3. Die Lip Design: 

The design and condition of the die lip play a crucial role in maintaining a consistent extrusion current. Uneven die lip gaps, worn-out or damaged die lips, or improper alignment can contribute to flow instabilities and erratic extrusion current.

4. Screw and Barrel Design: 

The selection and condition of the screw and barrel used in the extrusion process are important factors. Poorly designed screw geometries, damaged or worn-out screws, or imbalanced barrel heating can result in inconsistent molten plastic flow, leading to fluctuations in extrusion current.

Solutions to Address Fluctuations in Extrusion Current:

1. Material Control and Preprocessing: 

Prior to extrusion, thorough material inspection and control should be implemented. Ensuring material consistency, removing impurities, and properly drying the plastic resin can help improve the uniformity of molten plastic flow, minimizing extrusion current fluctuations.

2. Temperature Control: 

Precise temperature control throughout the extrusion process is essential. Regular calibration of the temperature sensors, adequate heating/cooling systems, and maintaining consistent barrel temperature profiles can prevent overheating, cold spots, and uneven material flow, reducing variations in extrusion current.

3. Die Maintenance and Alignment: 

Regular inspection and maintenance of the die lip are critical to maintain a uniform flow of the molten plastic. Die lips should be periodically cleaned, repaired, or replaced as needed. Proper alignment of the die lip and control of the die gap can ensure a consistent extrusion current.

4. Screw and Barrel Maintenance: 

Implementing a regular maintenance schedule for screws and barrels is essential for optimizing extrusion performance. This includes cleaning, reconditioning, or replacing worn-out components. Additionally, using appropriately designed screws and barrels can enhance the overall stability of the extrusion process.

Large fluctuations in extrusion current during extrusion hollow blow molding can have detrimental effects on the final product's quality and consistency. By addressing the various causes and employing the suggested solutions mentioned above, manufacturers can mitigate these fluctuations and achieve better control over the extrusion process. 

The continuous improvement in material control, precise temperature management, proper die and equipment maintenance, and regular monitoring of the extrusion process parameters are key to achieving consistent extrusion current, resulting in high-quality hollow plastic containers.

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