How Extrusion Blow Molding Differs From Injection Molding?

If you operate a business that has a requirement for specially formed plastic bottles or containers, such as for juice and water bottles or liquid soaps and shampoos, it’s to your benefit to understand the various manufacturing processes for making those bottles and containers. What follows is an explanation of the extrusion blow molding process and how it differs from injection molding.

extrusion blow molding

Extrusion blow molding (EBM) is a manufacturing process whereby plastic is melted and extruded (that is, expelled to form a shape) into a hollow tube; a form or mold. (At this point of the process this material is generally referred to as a “parison,” which is a round melted mass that will then be molded; or formed.) The parison is held and sealed in the metal mold. Air is then blown into the mold thereby shaping it into the desired shape of the bottle or container. Once the plastic has cooled, the mold is opened and the part is discharged. There are two variations of extrusion blow molding: Continuous (with a constant extrusion of the parison) and Intermittent.

Injection molding (AmE or BrE), on the other hand, may seem similar but it is a different process. Injection molding is also a method of manufacturing products and parts by injecting material (such as plastic) into a mold. In this case, plastic in the form of pellets is melted and then injected (forced) into a mold where it cools and solidifies to the shape of the mold. The finished result is the exact copy of the mold.

The main difference between blow molding and injection molding is that blow molding is used for making hollow parts like water bottles and liquid soap containers. One of the key benefits of blow molding is that it can be used to manufacture complex shapes – something that can be of tremendous value for such things as product branding and identity. Injection molding is most often used for making solid parts, like kitchen products, tools, or parts and components. Furthermore, injection molding is able to produce large volumes of quality parts at a high rate of speed and with accuracy.

Having an understanding of the different manufacturing processes and knowing what method is best suited to product production is important for all aspects of prototyping, planning, manufacturing, and costing. The full list of criteria in choosing the right molding procedure, such as will apply to extrusion blow molding machine specifications must be considered. All this and more will need to be determined with the involvement of plastics mold engineers to determine the right plastics-molding process to benefit from the best solution.

Pet All Manufacturing Inc. offers a full range of injection and blow molding machinery as well as industry-leading expertise to advise all clients about the best solutions specific to their needs. Pet All Manufacturing serves a broad range of industries globally and can fulfill any client requirement for blow molding and injection molding equipment. All inquiries are welcomed. Contact the Canadian branch of Pet All Manufacturing by calling 905-305-1797 or by email at

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