What is Extrusion Molding

Extrusion molding is a continuous and efficient plastics processing technology commonly used to manufacture products such as pipes, profiles, films, and cable sheathing. It is gradually expanding into the automotive, medical, and packaging sectors. As global markets increasingly demand product stability and consistency, maintaining quality and reducing defects during the extrusion process are becoming key concerns for both buyers and manufacturers.

In many cases, extrusion defects are not simply a matter of equipment or process; raw material quality and supply chain stability are also key factors. As an international supplier of plastic raw material pellets, we not only offer a wide range of high-quality engineering plastics and general-purpose plastics, but also help customers reduce production defects at the source and improve product consistency.

The following will examine six common problems, their causes, and solutions, to help manufacturers and buyers overcome these pain points through optimized processes and a reliable raw material supply.

1. Voids & Bubbles

Typical manifestations: Bubbles and holes appear inside or on the surface of the product, reducing mechanical strength. This is particularly noticeable in transparent products.

Causes:

  ・Excessive raw material moisture content;

  ・Insufficient screw venting;

  ・Excessively high melt temperature leading to decomposition.

In-depth Solution:

  ・Use a vacuum drying oven to thoroughly dry hygroscopic materials (such as PA, THÚ CƯNG, Và máy tính);

  ・Use a vented screw or vacuum venting device;

  ・Strictly control the melt temperature.

Supplier Advantage: Our pellets are moisture-controlled and vacuum-packed before shipment, and can be accompanied by a test report, helping buyers reduce the risk of bubbles at the source.

2. Rough Surface

Typical symptoms: The finished product surface is dull and grainy, affecting appearance and subsequent coating or printing.

Causes:

  ・Die contamination;

  ・Poor raw material dispersion;

  ・Unstable temperature control.

In-depth Solution:

  ・Regularly clean the die;

  ・Select masterbatches with excellent dispersion or switch to twin-screw compounding;

  ・Maintain temperature fluctuations within ±2°C.

Supplier Advantages: The masterbatches and base materials we provide undergo rigorous ratio and compatibility testing, ensuring excellent dispersion and high stability, ensuring a smooth surface finish on the finished product.

3. Melt Fracture (Sharkskin)

Typical manifestations: Cracks or a "sharkskin" texture appear on the product surface.

Causes:

  ・Excessive shear rate;

  ・Excessively broad molecular weight distribution of the raw material.

In-depth Solutions:

  ・Adjust extrusion speed and temperature;

  ・Optimize die flow;

  ・Select raw materials with a narrow molecular weight distribution.

Supplier Advantages: We can recommend material grades with appropriate melt index and stable molecular weight distribution based on customer applications to minimize processing defects.

4. Dimensional Instability

Typical manifestations: Uneven pipe wall thickness, fluctuating profile dimensions, and poor stability.

Causes:

  ・Unstable pulling speed;

  ・Uneven cooling;

  ・Fluctuating raw material viscosity.

In-depth Solution:

  ・Use a frequency converter to precisely control the pulling speed;

  ・Maintain a cooling water temperature difference of ≤ 1°C;

  ・Optimize the screw structure.

Supplier Advantage: Our pellets undergo melt index (MFI) and thermal stability testing, helping manufacturers achieve more stable viscosity and ensure dimensional consistency.

5. Color Streaks

Typical manifestations: Uneven product color, streaks, or "snaking" flow marks.

Causes:

  ・Poor masterbatch dispersion;

  ・Large variability in raw material batches;

  ・Inadequate melt mixing.

In-depth Solution:

  ・Use a twin-screw extruder;

  ・Select masterbatch with good compatibility;

  ・Ensure stable raw material batches.

Supplier Advantage: We guarantee a stable batch supply and can provide small test samples upon request to avoid production losses caused by color variation.

6. Sagging & Deformation

Typical manifestations: Thin-walled products or pipes sag, sag, or twist after cooling.

Causes:

  ・Insufficient melt strength;

  ・Insufficient cooling;

  ・Insufficient traction.

In-depth solutions:

  ・Select high molecular weight or reinforced materials;

  ・Increase cooling trough length;

  ・Enter the sizing sleeve early.

Supplier Advantages: We offer reinforced, high-temperature-resistant, and specially modified pellets to meet customers' needs for high-strength products.

7. Quality Control and Testing Assurance

To help customers reduce extrusion defects, we not only supply raw materials but also provide the following additional support:

  ・Factory testing: Moisture content, melt index, and color difference control;

  ・Traceable batch reports ensure transparency in international procurement;

  ・Provide technical guidance to help customers optimize extrusion conditions.

8. Future Trends and Our Value

With increasing market demand for high performance, environmentally friendly, and stable supply chains, extrusion processes are moving towards energy conservation, digitalization, and green materials.

As a supplier of plastic raw material pellets, our strengths lie in:

  ・Stable supply capacity: Long-term partnerships ensure batch consistency;

  ・International experience: Familiarity with cross-border delivery and quality standards ensures supply chain security for our customers;

  ・Technical support: We not only sell raw materials but also provide application-level solutions;

  ・Flexible service: We support multi-batch and small-batch customization, reducing procurement risks.

Phần kết luận

The stability of extrusion molding depends on the synergy between equipment, processes, and raw materials. By partnering with reliable raw material suppliers, buyers can not only avoid common production defects but also gain advantages in delivery time, cost control, and market competitiveness.

Nếu bạn đang tìm kiếm một long-term partner for high-quality plastic raw material pellets, we will help your manufacturing business reach new heights with our stable supply chain, strict quality control, and global service experience.