When it comes to plastic injection molding, mold design is everything. A well-engineered mold not only ensures consistent, high-quality parts—it also helps reduce cycle times, minimize waste, and avoid costly defects. At Nylacarb, we’ve spent decades perfecting our approach to mold design. Whether you’re an OEM, engineer, or product developer, here are six mold design best practices to help your next project succeed.
1. Start With the End Use in Mind
Before CAD software ever opens, we ask: What is the part’s function? What environment will it operate in? Will it be load-bearing, exposed to UV, or require specific tolerances?
Why it matters: Understanding the part’s application informs everything from resin selection to gate location. Good mold design supports the part’s performance in the real world—not just on paper.
2. Prioritize Uniform Wall Thickness
Uneven wall thickness is one of the most common causes of defects in injection molded parts. Thick sections cool slower, leading to shrinkage, warping, or sink marks.
Our tip: Whenever possible, maintain consistent wall thickness throughout the part. If variation is necessary, transition gradually to avoid stress concentrations.
3. Design for Manufacturability (DFM)
Mold design should always consider how the part will be manufactured and ejected. Complex geometries, deep undercuts, or tight corners might require unnecessary secondary operations or complicated tooling.
At Nylacarb, we conduct a thorough DFM analysis for every project to ensure the part can be produced efficiently without sacrificing quality.
4. Think Ahead on Gating and Venting
Proper gate placement affects the flow of molten plastic into the mold cavity, while venting ensures trapped air doesn’t cause voids or burn marks.
Best practice: Position gates to allow even filling and minimize weld lines. Add vents strategically in areas where air is likely to become trapped.
5. Choose the Right Steel and Surface Finishes
Tooling material plays a major role in the mold’s longevity and surface quality. High-volume production might call for hardened tool steel, while prototype molds can often use aluminum.
Pro tip: Consider how finishes (like polishing or texture) will affect mold release, cosmetic appearance, and even how light reflects off the part.
6. Plan for Cooling Efficiency
Efficient cooling reduces cycle time and improves part consistency. Cooling channels should be evenly distributed and as close as safely possible to the mold cavity.
What we do at Nylacarb: We use advanced mold flow analysis and 3D modeling to simulate and optimize cooling before the mold is ever built.
Mold Design Is More Than Just Engineering—It’s Strategy
Investing time in great mold design upfront saves time and money later in production. At Nylacarb, our in-house engineers work closely with clients through every stage of the mold development process—from concept and DFM to tooling, testing, and final production.
Looking to bring your next plastic part to life with expert precision?
Contact Nylacarb today and let’s talk about how we can turn your concept into a production-ready part with long-term performance in mind.