Aug 07/24
5 Key Differences Between Injection and Blow Molding
U.S. plastics is a $371 billion industry. Innovations in plastic resins and production methods have contributed to almost every major industry, from automotive to aerospace, construction to consumer goods.
Injection and blow molding are two popular plastic molding techniques. They both have different pros and cons, and each is preferable for distinct applications.
Below are five key distinctions between injection and blow molding. Keep reading to learn more about these unique processes, so you can decide which one might be right for your project or industry.
1. Manufacturing Processes
The manufacturing processes of injection and blow molding are quite distinct. Injection molding, which has been around for more than 150 years, uses high pressure to inject molten thermoplastic into a two-part mold. Once the plastic cools and solidifies, the mold is opened and the part is ejected.
Blow molding uses melted plastic as well. It is formed into a parison, which is a tube-like form with a hole in one end.
The parison is placed into the mold and air is blown into it. Air pressure expands the plastic to fit the mold’s shape.
The plastic cools and solidifies. After, the mold is removed and the process is repeated.
2. Mold Design
Injection molding uses a two-part mold cavity or core. It also can involve multiple cavities for mass production. The mold allows for making very complex and precise parts, one of the biggest injection molding benefits.
Blow molding also involves a two-part mold cavity that forms the exterior shape of the product. The design focuses on creating a uniform wall thickness. This is important for the structural integrity of very thin walls.
3. Moulding Applications
Both blow molding and injection molding are suitable for high-volume production and can use a range of plastic resins. However, the types of parts they make are distinct.
Injection molding can be used to make a variety of complex and detailed parts. These include automotive components, electronics, medical devices, and other items.
Blow molding is used to produce single-component hollow containers, such as bottles, air ducts, or fuel containers. These are impossible to produce using injection molding.
The flip side is that producing thin-walled hollow parts is the only suitable application for blow molding. It cannot be used to make intricate parts or thick-walled products.
4. Material Usage and Waste
Since injection molding is a highly controlled process, there is very little excess plastic waste. Also, materials like sprues and runners can be reused.
Blow molding can result in more material waste. That is due to trimming excess material away from the neck and bottom of finished products.
5. Cost
One major benefit of blow molding is that it is more economical than injection molding. That is because setup costs, including tooling, for injection molds are substantially higher. However, both injection and blow molding are relatively cost-effective options for large production runs.
Find Injection and Blow Molding Services Near You
Now that you understand the differences between injection and blow molding, you can determine which one may be best for your project or business. An experienced manufacturer can further advise you on the pros and cons of each method.
Mayco International is a provider of Tier 1 interior and exterior automotive components. We are headquartered in Michigan but have affiliates throughout the world. Contact us today to schedule a free consultation.