Today's KNOWLEDGE Share : Injection Mold Vent Depth Design: A Common Challenge We Face

Today's KNOWLEDGE Share 

Injection Mold Vent Depth Design: A Common Challenge We Face


🔍 A critical yet often overlooked challenge in injection molding: How to design mold vent depth correctly? This parameter directly impacts part quality—and striking the right balance is far from easy.



⚠️ Too deep, and you get part flash; too shallow, and trapped air causes burn marks. So, what’s the solution?

✅ Ideally, vent depth should align with material properties—following material data sheet (MDS) recommendations, accounting for melt viscosity and melt flow rate (MFR). A one-size-fits-all approach doesn’t work.

📌 Yet, in my observation, many factories (at least in China) commonly use a conservative 0.015mm depth for most molds—this standard is often adopted to avoid flash, but it overlooks its inadequacy for most materials and mold cavity geometries, which causes frequent venting-related defects. Adding to this, flash is more likely in thin-walled sections, as higher shear rates reduce plastic melt viscosity, increasing seepage.

🤝 This is not criticism, just an operational observation. I’m eager to hear peers’ thoughts: What guidelines do you use for vent depth? How do you balance air release and flash prevention?

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