10 Essential Tips for Design for Manufacturability in Plastics

At Plast Fab Works, we’ve spent years perfecting the art of manufacturing high-quality plastic parts. A key to our success is Design for Manufacturability (DFM), a process that ensures your designs are optimized for efficient production without sacrificing quality or performance. Whether you’re new to plastic part design or a seasoned engineer, these 10 tips will help you create parts that are cost-effective, reliable, and ready for production.

What is Design for Manufacturability (DFM)?

DFM is the practice of designing products with the manufacturing process in mind, particularly for methods like plastic injection molding. For plastics, DFM focuses on creating parts that are easy to mold, assemble, and scale while minimizing defects and costs. By addressing common questions like “What is DFM?” and “Why is it important for plastics?”, we aim to provide actionable insights for your projects.

Why DFM Matters for Plastics

Plastics are versatile, but without DFM, designs can lead to issues like mold complexity, material waste, or production delays. DFM bridges the gap between industrial design and manufacturing, ensuring parts are both functional and economical. It also aligns with lean manufacturing principles by reducing waste and optimizing production.

Below, we share our top 10 tips for DFM in plastics.

10 Essential Tips for DFM in Plastics

1. Maintain Uniform Wall Thickness

Consistent wall thickness prevents defects like sink marks, warping, and voids caused by uneven cooling. Variations in thickness can lead to stress concentrations and longer cycle times. Aim for uniform walls, and if transitions are needed, make them gradual.

Why it matters:

Uniform walls ensure consistent quality and reduce production costs. For more on how wall thickness impacts molding, explore our Injection Molding Tonnage Calculator.

2. Incorporate Draft Angles

Draft angles are slight tapers on vertical surfaces that allow parts to eject smoothly from the mold. Without them, parts may stick, increasing the risk of damage or mold wear. A draft angle of 1° to 2° per side is typically sufficient, though this varies by material and design.

Why it matters:

Proper draft angles streamline ejection and extend mold life.

3. Use Ribs and Bosses Wisely

Ribs and bosses add strength and rigidity without increasing wall thickness. However, ribs should be no thicker than 60% of the nominal wall to avoid sink marks, and bosses should be supported by ribs to prevent sinking.

Why it matters:

Well-designed ribs and bosses enhance structural integrity while keeping parts lightweight.

4. Avoid Undercuts or Design for Moldability

Undercuts complicate mold design and increase costs by requiring side actions or collapsible cores. If undercuts are necessary, evaluate their purpose and explore alternatives like redesigning the part to eliminate them.

Why it matters:

Minimizing undercuts simplifies molds and reduces expenses. Learn about advanced molding techniques in our blog on Insert Molding vs Overmolding.

5. Select the Right Material

Choosing the right plastic is critical for both performance and manufacturability. Consider factors like strength, flexibility, thermal stability, and moldability. For example, selecting a material with the right melt flow rate ensures proper mold filling.

Why it matters:

The right material balances performance with production efficiency, addressing questions like “How does material selection affect manufacturability?”

6. Consider Gate Location and Mold Design

The gate, where molten plastic enters the mold, affects filling patterns and part quality. Proper gate placement minimizes weld lines and ensures even filling. Mold design, including cooling channels and venting, also impacts cycle time and part accuracy.

Why it matters:

Optimized mold design reduces defects and speeds up production. For more on mold design, check out our Top 5 Books to Learn Mold Design for Injection Molding.

7. Use Fillets and Radii

Fillets and radii (rounded corners) reduce stress concentrations and improve material flow during molding. Sharp corners can lead to cracking or poor mold filling, compromising part strength.

Why it matters:

Fillets enhance durability and aesthetics, making parts more reliable.

8. Minimize Part Count and Simplify Design

Reducing the number of components in an assembly lowers manufacturing and assembly costs. Integrate parts where possible to simplify production and improve reliability by reducing potential failure points.

Why it matters:

Simpler designs are easier to produce and maintain.

9. Design for Assembly

For multi-part products, incorporate features like snap fits, tabs, or locators to simplify assembly. This reduces labor costs and minimizes the need for secondary operations, aligning with Design for Assembly.

Why it matters:

Assembly-friendly designs save time and improve product quality. Explore related techniques in our blog on 6 Popular Plastic Manufacturing Techniques.

10. Collaborate with Manufacturing Experts Early

At Plast Fab Works, we emphasize early collaboration to catch potential issues before they become costly. Our experts can guide you on feasible designs, material choices, and production strategies, ensuring your project is optimized from the start.

Why it matters:

Early collaboration prevents redesigns and ensures cost-effective production. For tips on profitability, read our 5 Necessary Steps to Make a Profit from Injection Molding Projects.

Additional Considerations

• Auxiliary Equipment:

  Proper equipment, like dryers and chillers, supports efficient molding. Learn more in our blog on 3 Essential Types of Auxiliary Equipment for Injection Molding.

  
  

• Specialized Applications:

  For parts like cable glands, DFM ensures functionality and manufacturability. See our M28 Plastic Cable Gland Guide.

  
  

• Industry Expertise:

  Partnering with experienced manufacturers like Plast Fab Works ensures quality. Check out our insights on 5 Best Injection Molding Companies in India.

FAQs

1. What is Design for Manufacturability (DFM) in plastics?

Design for Manufacturability (DFM) is the practice of designing plastic parts to optimize production, particularly for plastic injection molding. It ensures parts are easy to mold, assemble, and scale while minimizing defects and costs, leading to efficient, high-quality production.

2. Why should undercuts be minimized in plastic part design?

Undercuts complicate mold design, requiring costly mechanisms like side actions. Minimizing undercuts simplifies production and reduces expenses.

3. What is mold shrinkage, and why is it important to account for it?

Mold shrinkage is the size reduction of plastic as it cools. Accounting for it ensures parts meet dimensional specifications, avoiding costly rework. Proper mold design mitigates shrinkage issues.

4. When should DFM principles be applied in the design process?

Apply DFM principles early in the design phase to allow for adjustments that prevent costly redesigns. Early integration optimizes manufacturability and reduces production risks.

5. What are the benefits of collaborating with manufacturing experts during the design phase?

Collaboration with experts, like those at Plast Fab Works, ensures designs are feasible and optimized, preventing issues and reducing costs. Check out 8 Key Factors for Choosing a Supplier.

6. How does DFM contribute to cost savings in plastic part production?

DFM reduces material waste, production time, and defects by optimizing designs, leading to significant cost savings.

Conclusion

By applying these 10 DFM tips, you can create plastic parts that are functional, cost-effective, and ready for production. At Plast Fab Works, we’re committed to helping you turn your designs into reality with our expertise in plastic injection molding and Design for Manufacturability. Contact us today to start your next project!