Injection Molding

9 Best Practices for Injection Mold Design

Discover the best practices in designing an injection mold to ensure high-quality, cost-effective, and timely production of plastic parts.

Injection molding, a process that takes precision and expertise to master, reigns as the most popular technique for manufacturing plastic parts at a large scale, with unparalleled accuracy and consistency. It relies on injecting molten plastic into a meticulously designed mold, cooling it, and then ejecting the finished part.

The real game-changer in this process is the design of the mold. A well-designed mold guarantees parts that meet specifications and withstand the rigors of the injection molding process. In this blog, we delve into the best practices for injection mold design, ensuring the production of top-quality parts.

1. Material Matters: Know Thy Plastic

Before designing the mold, it's crucial to gain a deep understanding of the material intended for injection molding. Various materials exhibit different properties that could influence the mold design. For instance, certain materials may shrink more than others when cooled, altering the size and shape of the final part. A keen understanding of the material's properties aids designers in crafting a mold that generates high-quality parts in line with the required specifications.

Plastic Pelets

2. Designing for Manufacturability: Keeping It Simple

A mold that's difficult or expensive to manufacture can inflate production costs and prolong lead times. Therefore, designers should aim to create molds that are simple to manufacture and require minimal post-processing.

3. The Parting Line: Placement is Key

The parting line, where the two mold halves meet, plays a significant role in the appearance and functionality of the finished part. It’s essential to strategically place the parting line to minimize its impact on the final product.

4. Flowing with the Mold: The Importance of Mold Flow Analysis

Mold flow analysis is a crucial step in mold design. This simulation predicts how the plastic material will flow through the mold, informing designers to optimize mold design, improve part quality, and reduce production costs.


5. Getting in the Gate: Choose Wisely

The gate, where the plastic enters the mold cavity, influences the quality and appearance of the final part. With a range of gate types like edge gates, tunnel gates, and hot runner gates, designers must consider gate design based on the material, part geometry, and desired part quality.

6. Venting: Letting it Breathe

Proper venting, allowing air to escape from the mold cavity during injection, is critical to avoid defects such as burns, voids, and warpage. Designers should ensure the mold is properly vented to prevent these issues.

7. Designing for Cooling: Chill Out

A critical step in the injection molding process is cooling. Optimal cooling of the plastic material can be facilitated through the use of cooling channels or inserts, leading to high-quality parts with minimal defects.

8. Ejector Pin Placement: Position Matters

Ejector pins, used to remove the finished part from the mold cavity, can impact the appearance and functionality of the final part. Designers should strategically place the ejector pins based on the part geometry and desired part quality.


9. Material Quality: Strength in Substance

The mold material's quality significantly impacts the performance and longevity of the mold. High-quality materials like tool steel and aluminum alloys are recommended for injection mold design. Although steel tools take longer to mill than aluminum, their lifespan considerably outpaces that of aluminum tools.


Ready to bring your design to life? Contact us today!

If you are considering to manufacture your product using injection molding, we can help you with your design for manufacturing needs. CADmore is dedicated to delivering the highest quality manufacturable designs with the quickest turnarounds.

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