Successful plastic injection molding starts with smart, efficient design. At Universal Plastic Mold (UPM), we collaborate closely with customers to optimize product design for manufacturing, ensuring quality, cost-efficiency, and scalability. From material selection to part geometry, several critical design considerations impact injection-molded parts’ performance, durability, and production efficiency.
Key Design Factors for Injection Molding Success
1. Part Geometry & Wall Thickness
Designing parts with uniform wall thickness is essential in plastic injection molding. Variations in thickness can lead to warping, sink marks, or other defects due to inconsistent cooling times. Thin, uniform walls also allow faster cooling, reducing cycle times and improving production speed.
- Best Practices:
- Maintain consistent wall thickness to avoid potential defects.
- Thin walls improve cooling efficiency and reduce material usage.
- Reinforce thinner areas with ribs or gussets for added strength without increasing weight.
2. Draft Angles
Including appropriate draft angles in your design is critical for ensuring easy removal of parts from the mold. Without a draft, parts may become stuck, leading to production delays and potential damage to the mold and part.
- Best Practices:
- Apply a minimum draft angle of 1-2 degrees on vertical surfaces.
- Increase draft for textured surfaces to prevent drag during ejection.
3. Material Selection
Choosing the right plastic material for your part is crucial to achieving the desired strength, flexibility, and durability. Each material has unique characteristics that can affect impact resistance, temperature tolerance, and chemical compatibility.
- Common Thermoplastics Used:
- ABS (Acrylonitrile Butadiene Styrene): Offers strength and impact resistance.
- Polypropylene: Great for flexibility and chemical resistance.
- Nylon: Excellent for parts requiring toughness and wear resistance.
At UPM, our engineers can help you select the ideal material for your project based on the part’s functional requirements and environmental conditions.
4. Shrinkage & Tolerances
All plastics shrink as they cool. Designers must account for shrinkage rates during molding to ensure that the final dimensions match the required specifications. Tolerance levels should also be factored into the design to allow for small variations in part dimensions.
- Best Practices:
- Incorporate material-specific shrinkage factors into mold designs.
- Use appropriate tolerances to balance precision with cost-effective production.
5. Gate Placement
Gate design and placement determine how molten plastic flows into the mold. Proper gate placement helps reduce flow marks, voids, and warping while ensuring even filling of the mold cavity.
- Best Practices:
- Place gates in areas that minimize flow lines and blemishes on the visible part surface.
- Consider multiple gates for larger or complex parts to ensure uniform fill.
6. Ribs, Bosses, and Undercuts
Design features like ribs, bosses, and undercuts can add strength and functionality to your part without increasing material use. However, careful design is needed to avoid issues like warping, sink marks, or difficult mold ejection.
- Best Practices:
- Use ribs to strengthen walls without increasing thickness.
- Minimize undercuts to reduce mold complexity and production costs.
- Ensure that bosses (mounting points) have enough clearance and wall support for strength without compromising the part.
7. Surface Finish and Texturing
The surface finish impacts both the appearance and functionality of the final part. A smooth surface may be desirable for aesthetics, while textured surfaces hide imperfections or provide grip.
- Best Practices:
- Incorporate draft angles to accommodate surface textures.
- Consider post-molding processes if a highly polished or textured finish is required.
Cost-Saving Design Tips for Plastic Injection Molding
1. Simplify the Design
Complex designs increase the cost of mold making and production. Simplifying the part’s geometry can lead to cost savings and improve manufacturability.
2. Minimize Secondary Operations
Designing parts that come out of the mold as close to the finished product reduces the need for secondary operations like trimming, drilling, or finishing.
3. Optimize for Mold Durability
Designing parts with fewer moving elements, like sliders or lifters, can extend the life of the mold and lower maintenance costs.
Collaborative Design Process at UPM
At Universal Plastic Mold, we offer a collaborative design process that ensures every part is optimized for manufacturability and cost-efficiency. Our engineers work closely with your designers to identify potential design improvements, reduce production costs, and enhance product performance.
Industries We Serve
UPM’s design expertise in plastic injection molding serves a wide range of industries, including:
- Automotive
- Consumer Goods
- Electronics
- Hardware
- Medical and Pharmaceutical
- Packaging
- Pool and Spa
- Solar
We help businesses across these sectors develop plastic parts that meet exact performance and design specifications while streamlining production.
Ready to Optimize Your Design?
Contact Universal Plastic Mold today to start your project for expert advice on designing plastic injection molding.