Analysis of Reasons for Injection Molding Flow Marks and Sticking to the Mold in PVC Compound Injection Molding

1. Injection Molding Flow Marks Problem

Analysis of Causes of Injection Molding Flow Marks

Material Factors: Insufficient melt fluidity and too - fast cooling lead to discontinuous flow paths. Unreasonable formula design, especially insufficient lubricant, causes uneven shear friction heat generation. For PVC compound, these factors directly affect the molding quality.

Process Parameter Factors: Slow injection speed makes the melt unable to fill adequately. Low temperature of the barrel/mold reduces melt fluidity, a key point for PVC compound processing.

Solutions

Material Optimization: Adjust the formula to ensure reasonable addition of lubricants and stabilizers. PVC compound should be dried at 80 - 90℃ for 2 - 4 hours to avoid moisture volatilization, crucial for improving flow properties.

Process Parameter Optimization: Increase injection speed and pressure to ensure consistent melt front temperature. Adjust temperature settings to reduce temperature difference, optimizing processing conditions for PVC compound.

2. Injection Molding Sticking to the Mold Problem

Analysis of Causes of Sticking to the Mold in Injection Molding

Mold Aspects: Improper mold - surface treatment and lack of long acting release coating. Unreasonable demolding structure (e.g., insufficient demolding slope) affects the release of PVC molded products.

Process Aspects: Improper injection temperature leads to material decomposition or increased adhesion. Excessively high injection pressure causes over - filling, prone to cause sticking - to the mold in PVC compound injection molding.

Solutions

Mold Improvement: Optimize mold surface treatment and adopt long acting release surface coating. Ensure a reasonable demolding structure to facilitate smooth release of products made from PVC compound.

Process Parameter Optimization: Adjust injection temperature to prevent excessive decomposition and sticking to the mold. Adjust injection pressure to avoid over filling, an important measure for stable PVC compound injection molding.

By addressing these factors and solutions, manufacturers of PVC compound can effectively enhance the quality of injection molded products and reduce defects like flow marks and sticking to the mold. 

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