Ever wondered what blow molding is? Here's a quick-fire overview of the manufacturing process, including its advantages, disadvantages, and application areas.
Blow molding is a plastics manufacturing process used mainly to manufacture hollow parts and products from a wide range of thermoplastics.
The process is named the way it is because it involves blowing air into molten plastic almost like a balloon until it fills the cavity of a mold tool. There are three main types: extrusion, injection, and injection stretch.
All input materials are thermoplastics, and many are similar to those used in injection molding, such as POM, ABS, polystyrene, and polycarbonate among others.
The blow molding process has been around for thousands of years and remains essentially unchanged. The main difference with the modern process is that it’s heavily automated. The general process for extrusion blow molding is as follows:
In the case of injection and injection stretch blow molding, the parison is replaced with a preform, which is produced through injection molding. The associated tools are often made from aluminum or steel and are great for thousands of parts.
Naturally, not all plastic products are suited for blow molding. Here’s where the process shines and fails.
Blow molding is used to manufacture many different types of products, such as ducting for automotive, plastic bottles, food containers, and even things as large as garbage bins.
So how do you evaluate if your part is suitable for this process? If it’s hollow, has thin walls, or is an enclosed shape with undercuts — with which injection molding would struggle — blow molding might be the answer.
If you have something you think might be a good fit for blow molding, try one of these companies:
License: The text of "Blow Molding – The Basics" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.
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