SEVEN RULES OF EFFECTIVE VENTING
To conclude, traditional machined vents, sintered vents, and porous pins and plugs all have their place, depending on the part, flow path, and plastic material. The right approach will vary depending on your material and your process, so collaboration among material supplier, moldmaker, part designer, and molder to determine proper venting is essential.
Here are seven general guidelines to keep in mind regardless of the type of venting option you’re using:
1. Provide as many pathways as possible with sufficient area to allow trapped air and gases to escape from the mold quickly and cleanly.
2. The pathways should lead from the edge of the cavity directly to the outside of the mold.
3. Vents must be deep enough to let out air and gases, but not deep enough to let out plastic.
4. Vents should be regularly inspected and cleaned to prevent buildup.
5. Pay attention to excessive clamp pressures that can close vents.
6. Don’t forget to vent the runner, sprue, and cold-slug wells. This will help the plastic to inject quickly at lower pressures, reduce backpressure, improve flow rate, reduce part stress, and shorten cycle times.
7. Review inserts, slides, and cores for venting, too.
The article comes from China injection mold manufacturer - Mold Best Assurance Company Limited, website is www.mbamoldanddesign.com
