Improve Plastic Injection Molded Parts With Draft

How Draft Can Improve Plastic Injection-Molded Parts

Draft, an angle incorporated into plastic part design, plays a crucial role in the ejection process, leading to improved moldability and manufacturing outcomes.

Optimizing Part Designs Including draft in plastic part designs is essential to prevent sticking and ejector pin push marks on the outward surface during ejection. It is important to incorporate proper draft angles or tapers on the surface of injection molded parts to ensure smooth ejection. Often, it  is overlooked during prototyping stages with CNC machining or 3D printing, but it should be taken into consideration if these prototypes will ultimately be injection molded. Neglecting draft in the initial design phase can result in increased time and costs during the manufacturing process.

Potential Pitfalls of Ignoring Draft Failing to include it in the design can lead to various issues such as part bending, poor surface finishes, breakage, or warping due to stresses on the molded part. These problems can cause sticking, breaking, surface imperfections, and other manufacturing delays. Additionally, the absence of it may even damage the mold itself, resulting in costly repairs. Avoiding such pitfalls through proper planning is crucial.

Best Practices for Draft Angles While there is no one-size-fits-all draft angle for all plastic injection molded parts, the following are some general guidelines:

  • 0.5° on vertical applications
  • 1.5° to 2° per side as standard for plastic injection molding
  • 3° for light texture or shutoff (metal sliding on metal)
  • 5° or more for a heavy texture

A useful rule of thumb is 1° of draft per 1″ of cavity depth. However, it is important to consider various factors that can influence draft requirements, such as material selection, wall thickness, shrink rates, and manufacturing capabilities.

Seeking Expert Assistance If you have any questions or concerns about draft angles, you can upload your design on our platform or contact our Technical Experts at +1 931-766-7290. Our team is dedicated to helping you avoid future moldability issues and ensuring successful manufacturing outcomes.


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