Poor Discharge of the Machine Head in Extrusion Hollow Blow Molding

Extrusion hollow blow molding is a widely used manufacturing process for producing hollow plastic products. However, one common issue that can arise during this process is the poor discharge of the machine head.

This article aims to explore the reasons behind this problem and provide potential solutions to address it effectively.

Causes of Poor Discharge:
1. Insufficient melt temperature:

If the temperature of the molten plastic is too low, it can lead to poor flow and discharge from the machine head. This can occur due to inadequate heating or improper temperature control.

2. Inconsistent melt viscosity:

Variations in the melt viscosity can affect the flow characteristics of the plastic material. If the viscosity is too high, it can result in poor discharge, while low viscosity can cause instability in the extrusion process.

3. Blockage or contamination:

The presence of foreign particles, contaminants, or polymer degradation products can obstruct the flow of the molten plastic, leading to poor discharge. This can occur due to inadequate filtration or poor maintenance of the machine head.

4. Inadequate die design:

The design of the die plays a crucial role in ensuring proper discharge. If the die is poorly designed or worn out, it can cause flow restrictions and result in poor discharge.

Solutions to Improve Discharge:
1. Optimize melt temperature:

It is essential to maintain the appropriate melt temperature for the specific plastic material being processed. Regular monitoring and adjustment of the heating system can help achieve the desired melt temperature, ensuring smooth discharge.

2. Control melt viscosity:

Proper control of the melt viscosity can be achieved by adjusting the processing parameters such as melt temperature, screw speed, and back pressure. This can help maintain a consistent viscosity, promoting better discharge.

3. Ensure cleanliness and filtration:

Regular cleaning and maintenance of the machine head, including the removal of any contaminants or degraded polymer, is crucial. Additionally, implementing effective filtration systems can prevent blockages and improve discharge.

4. Optimize die design:

If the poor discharge is attributed to the die design, it may be necessary to modify or replace the die. Consulting with experts in die design can help ensure the die geometry is optimized for the specific application, promoting efficient discharge.

Poor discharge of the machine head during the extrusion hollow blow molding process can significantly impact the quality and productivity of plastic manufacturing. By understanding the causes behind this issue and implementing appropriate solutions, manufacturers can overcome this challenge and achieve improved discharge, leading to better product quality and process efficiency.

Regular maintenance, proper temperature control, and optimized die design are key factors in addressing this problem effectively.