Factors Affecting The Deformation Of Injection Molded Parts

There are numerous factors that influence the injection molding of mold parts, greatly impacting mold design and casting. Let's analyze several key factors:

1. Mold Opening Direction and Parting Line: Choosing an appropriate parting line helps avoid undercuts in the mold opening direction, thereby enhancing appearance and performance.

2. Proper Draft Angles: Implementing suitable draft angles helps prevent product hairlines (flash) and top damage, such as whitening, deformation, or cracking.

3. Wall Thickness: Various plastics have specific wall thickness ranges, typically between 0.5 to 4 mm. Exceeding 4 mm can lead to issues like prolonged cooling times and shrinkage marks, necessitating a reconsideration of the product's structure. Uneven wall thickness can cause surface shrinkage, air pockets, and weld lines.

4. Reinforcement Rib Application: Using reinforcement ribs reasonably enhances product rigidity and reduces deformation.

5. Small Fillet Radii: Small fillet radii can concentrate stress in the product, resulting in cracking. It can also cause stress concentration in the mold cavity, leading to cavity cracking.

6. Axial Holes and Mold Opening Direction Alignment: Aligning holes axially with the mold opening direction can prevent core pulling, with draft angles applied when necessary.

7. Core-Pulling Mechanism: When parts cannot be smoothly ejected in the mold opening direction, consider designing injection mold core-pulling and slider mechanisms.

8. Embedded Components: Embedding components in injection molded products can increase local strength, hardness, dimensional accuracy, and allow for small threaded holes (shafts) to meet specific requirements. This, however, increases product costs. Commonly used components are copper but can also be other metals or plastic parts. The surrounding plastic should be appropriately thickened to prevent stress-induced cracking.

9. Product Labeling: Product labels are generally placed on flat areas inside the product and are designed as protrusions. Positioning labels on surfaces with a consistent orientation relative to the mold opening direction can prevent tearing.

10. Dimensional Tolerances: Due to the unevenness and uncertainty of shrinkage during injection molding, designers should determine dimensional tolerances according to the plastic material used and the component's usage requirements, following standard specifications.

11. Deformation of Injection Molded Parts: Enhancing the structural rigidity of injection molded products reduces deformation. Avoiding flat structures, incorporating reasonable flanges, and using protrusions and depressions are advisable.

12. Latch Locations:

- Design latch devices that multiple latches can share simultaneously, increasing the overall device's lifespan and adding strength.

- Strictly control tolerance requirements for latch-related dimensions; too many undercuts can lead to latch damage, while too few can result in loose assembly.

13. Welding (Hot Plate Welding, Ultrasonic Welding, Vibration Welding): Implementing welding processes can improve joint strength and simplify product design.

14. Balancing Process and Product Performance:

- When designing injection molded products, it's essential to consider the trade-offs between product appearance, performance, and the manufacturing process.

- When injection molding defects cannot be avoided in structural design, try to place them in concealed areas of the product.

Translation into English:

Factors Affecting Deformation in Injection Molded Parts

There are numerous factors that influence the injection molding of mold parts, greatly impacting mold design and casting. Let's analyze several key factors:

1. Mold Opening Direction and Parting Line: Selecting the appropriate parting line helps avoid undercutting in the mold's opening direction, thereby improving both appearance and performance.

2. Proper Draft Angles: Employing suitable draft angles helps prevent product flash and top damage, such as whitening, deformation, or cracking.

3. Wall Thickness: All plastics have specific ranges for wall thickness, typically between 0.5 to 4 mm. Exceeding 4 mm can lead to issues like extended cooling times and shrinkage marks, necessitating a reevaluation of the product's structure. Uneven wall thickness can result in surface shrinkage, air pockets, and weld lines.

4. Reinforcement Rib Application: Thoughtful application of reinforcement ribs enhances product rigidity and diminishes deformation.

5. Small Fillet Radii: Insufficient fillet radii can concentrate stress in the product, leading to cracks. It can also cause stress concentration in the mold cavity, resulting in cavity cracks.

6. Axial Holes and Mold Opening Direction Alignment: Aligning axial holes with the mold's opening direction can prevent core pulling, with draft angles employed as needed.

7. Core-Pulling Mechanism: If parts cannot be smoothly ejected in the mold's opening direction, consider designing an injection mold core-pulling and slider mechanism.

8. Embedded Components: Introducing components within injection-molded products can enhance local strength, hardness, dimensional accuracy, and accommodate small threaded holes (shafts) to meet specific requirements. However, this may increase production costs. Commonly used components are copper, although other metals or plastic parts are also viable options. Surrounding plastic should be suitably thickened to prevent stress-induced cracking.

9. Product Labeling: Product labels are typically positioned on flat areas within the product and designed as protrusions. Placing labels on surfaces with a consistent orientation relative to the mold's opening direction can prevent tearing.

10. Dimensional Tolerances: Due to the uneven and uncertain nature of shrinkage during injection molding, designers should determine dimensional tolerances based on the plastic material used and the component's usage requirements, following standard specifications.