Delamination is a separation or layering of the molded part, often caused by poor material compatibility or inadequate adhesion between layers.


Delamination is a common defect encountered in injection molding, characterized by the separation or splitting of layers within the molded part. This defect occurs when there is a lack of proper bonding between adjacent layers of material during the molding process, leading to compromised part quality, structural weaknesses, and reduced performance. Delamination not only affects the aesthetics but can also result in functional defects such as reduced strength, dimensional instability, and poor surface finish. Understanding the causes of delamination and implementing effective preventive measures are crucial for manufacturers striving to produce high-quality molded parts. In this article, we delve into the intricacies of delamination, identifying its root causes, and providing insights into minimizing this injection molding defect.

Causes of Delamination

Delamination can occur due to several factors related to the injection molding process:

  1. Inadequate Material Compatibility: Delamination can result from the use of incompatible materials in the multilayer or composite structure of the molded part. Differences in material properties, such as melting temperature, thermal expansion coefficient, or adhesion characteristics, can hinder proper bonding between layers.
  2. Poor Material Handling and Preparation: Improper handling or storage of the material before molding can lead to contamination or degradation, affecting the bonding between layers and causing delamination. Moisture absorption in hygroscopic materials can also contribute to delamination.
  3. Inadequate Melt Temperature and Pressure: Incorrect melt temperature or pressure during the injection process can prevent proper fusion between layers, resulting in delamination. Insufficient melt temperature may hinder molecular bonding, while excessive pressure can cause layer separation.
  4. Mold Design Considerations: Inadequate mold design, including improper cooling, insufficient venting, or improper gate location, can contribute to delamination. Improper cooling can lead to uneven material solidification, preventing proper layer bonding.
  5. Processing Parameters: Improper processing parameters, such as injection speed, holding pressure, or dwell time, can result in delamination. Inconsistent or incorrect processing conditions can compromise the bonding between layers and cause delamination defects.


To minimize the occurrence of delamination and produce visually appealing and structurally sound molded parts, manufacturers can adopt the following preventive measures:

  1. Material Selection and Compatibility: Choose compatible materials with similar properties for multilayer or composite structures. Consider factors such as adhesion characteristics, melting temperature, and thermal expansion coefficients to promote proper bonding between layers.
  2. Material Handling and Preparation: Ensure proper material handling and storage to prevent contamination or degradation. For hygroscopic materials, implement proper drying techniques to minimize moisture absorption.
  3. Melt Temperature and Pressure Optimization: Optimize melt temperature and pressure based on material properties and part requirements to facilitate proper bonding between layers. Conduct process validation to determine the appropriate parameters.
  4. Mold Design Considerations: Ensure proper mold design, including adequate cooling channels, venting, and gate location, to promote uniform cooling and proper bonding between layers. Collaborate with mold designers and engineers to optimize mold design for the specific part requirements.
  5. Process Optimization and Monitoring: Fine-tune processing parameters, such as injection speed, holding pressure, and dwell time, to minimize the risk of delamination. Implement robust process monitoring and control systems to detect and address any variations or abnormalities during production.


Delamination poses challenges in injection molding, affecting the quality, structural integrity, and performance of molded parts. By understanding the causes of delamination and implementing preventive measures, manufacturers can effectively minimize its occurrence. Optimization of material selection and compatibility, material handling, melt temperature and pressure, mold design considerations, and process optimization contribute to mitigating delamination defects. By addressing this defect, manufacturers can produce visually appealing, structurally robust, and high-quality molded parts,