Thin wall injection molding is a specialized injection molding process for producing plastic parts with wall thicknesses below 1 mm. It requires high-performance injection molding machines, well-designed molds, low viscosity plastics, and tight process control to fill thin sections completely and minimize defects. Key applications include thin wall packaging, electronic housings, and lightweight consumer products.

• We usually plastic parts with a wall thickness of less than 1 mm are called thin wall parts, and the injection molding process for making such thin wall plastic parts is called thin wall injection molding.
• In injection molding, when L/T is greater than 150, it is called thin wall, and “L” refers to the longest distance from the melt into the mold cavity to the full filling.”T” is the corresponding average wall thickness.

These are some considerations of thin wall moling:

• Specialized injection molding machines with high injection pressures and speeds are required to fill thin wall parts.
• Mold design is critical to ensure proper and balanced filling of the thin wall sections. Flow leaders and gates need to be optimized.
• Materials must have low viscosities to flow easily into thin cavities and minimize defects like short shots. Common materials are PS, PP, PE, PVC.
• Processing parameters including melt temperature, injection speed, packing pressure, and cooling time need tight control to ensure adequate filling without warpage.
• Demolding can be challenging for thin parts and requires angled drafts and proper ejection systems.

Producing high quality, dimensionally accurate thin wall parts via injection molding requires careful attention to process control, mold design, material selection, and simulation analysis.

Here are some key challenges associated with thin wall injection molding:

• Fill and packing – Thin walls make it difficult to fill the mold cavity completely and obtain proper fusion across the cross-section. This can lead to short shots, weak points, and cosmetic defects. Precise process control is required.
• Dimensional tolerance – Thin walls are prone to variation and distortion. Maintaining tight dimensional tolerances across thin sections is challenging.
• Warpage – Residual stresses tend to warp and distort thin parts upon ejection. Parts may require additional cooling time in the mold to enhance dimensional stability.
• Demolding – Thin parts can deform or break when ejected from the mold due to inadequate stiffness. Proper draft angles, ejector design and control of shrinkage stresses are needed.
• Surface defects – Any minor variation in melt flow, temperature or mold surface can result in visible flow lines, jetting, sink marks and other defects on thin walls. Highly polished mold surfaces are essential.
• Resin selection – The resin must have low viscosity and high strength at thin wall thickness.Low viscosity can increase material fluidity, accelerate filling, and increase the probability of successful molding.
• Mold strength – High injection pressures are needed to fill thin walls, exerting high clamp forces. The mold must have adequate mechanical strength.

Thin-wall molding has significant advantages in reducing weight, saving materials, improving strength, saving costs, optimizing design, and facilitating integrated design and assembly. However, in practical applications, it is also necessary to select appropriate molding processes and materials based on specific product requirements and process conditions to fully exploit their advantages and overcome potential challenges. Take a look at its main advantages below:

• Lightweight: Thin-wall molding can reduce the weight of the product, making it lighter, more portable, and easier to use.
• Material saving: Using less material to manufacture the product, reducing production costs.
• High efficiency: Thin-wall molding can typically achieve rapid production, improving production efficiency.
• Increased design flexibility: It is possible to manufacture more complex shapes and structures, providing more possibilities for product design.
• Low cost: Less material saves costs, shorter cycle times, and faster speeds save injection molding costs, all of which are ways to save costs.
• Good heat dissipation: The thin-wall structure facilitates heat dissipation, which is important for some heat-generating equipment.

• Food packaging jar
• Automotive plastic parts
• Medical equipment
• Plastic containers
• Aerospace
• Consumer goods packaging box
• Electronic housing and protection
• Mobile & computer shell