In-Depth Analysis of Injection Molding and Blow Molding Processes — Q&A Edition

There’s a story in every cup, warmth in every life. Hello everyone, and welcome to "Dong Dong's Cup Talk" In our recent posts, some friends have privately messaged us asking about the differences between injection molding and blow molding. In fact, comparisons and analyses of these two processes are widely available online, including on a certain well-known search engine — just type in “differences between injection and blow molding,” and you’ll find extensive comparison articles. https://www.umbottle.com/ProductsDetail-OR-10022.htmlWe don’t need to show off amateur skills in front of experts, but as we’ve mentioned before, whenever friends have questions, we’ll do our best to answer them. Especially after reading many online comparison articles, we thought it would be helpful to explain the differences between these two processes in our own way, making it easier for everyone to understand.

In our sharing, we’ll focus on daily necessities, electronic products, and the cup and bottle industry — our area of expertise. https://www.umbottle.com/ProductsDetail-OR-10022.htmlWe’ll explain the process principles, equipment selection, material compatibility, and some case studies in an easy-to-understand manner. We hope you find it helpful. If our content proves useful, please don’t forget to give us a like. And if you want to stay updated with our future posts, be sure to follow us.

Every bit of your support is the driving force behind our tireless efforts. Oh, and by the way, our factory not only produces stainless steel cups but also plastic cups. https://www.umbottle.com/ProductsDetail-OR-10022.htmlWe also handle the production of various plastic molds and process food-grade plastic products. Hahaha, this isn’t an ad — really, it’s not!

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IV. Engineer’s Q&A: Solutions to Common Problems

Q: Shrinkage in injection-molded parts

A: Increase holding pressure (up to 80% of injection pressure) and extend holding time (add 0.5s per 1mm wall thickness).

Q: Uneven wall thickness in blow-molded products

A: Optimize the parison program (increase extrusion volume by 10% at the bottom)https://www.umbottle.com/ProductsDetail-OR-10022.htmland implement segmented mold temperature control (temperature difference ≤ 5°C).

Q: Key points for food-grade certification

A: Material selection — prioritize FDA 21 CFR certified grades (e.g., Eastman Tritan™ MX711).

The fundamental difference between injection molding and blow molding lies in their forming logic: injection molding focuses on structural precision, while blow molding emphasizes hollow shaping. https://www.umbottle.com/ProductsDetail-OR-10022.htmlBy scientifically selecting materials (e.g., heat-resistant PP and impact-resistant PCTG), accurately choosing processes (e.g., two-color injection molding and one-step blow molding), and optimizing parameters (e.g., holding pressure and parison control), the optimal balance between quality and cost can be achieved. We hope these insights provide practical reference for industry peers.