Understanding Blow Molding and Injection Molding Processes

We usually call it Extrusion Blow Molding. Extrusion Blow Molding is a single-stage process, the process starts with resin pellets or powder and delivers containers ready to be packaged. The process of blow molding follows the basic steps found in glass blowing. The process melt resin pellets or powder and then putting that into the cavity of a mold. Then use compressed air to inflate the molten plastic like a balloon so that it takes the shape of the mold but is hollow inside. The blow molding process is designed to manufacture very uniformly, thin-walled objects. The main advantage of the process is its ultimate flexibility. If you need to make lots of bottles, this is the process you need.

Injection molding is a method to obtain molded products by injecting plastic materials molten by heat into a mold, and then cooling and solidifying them. Plastic injection molding is ideal for high-volume orders and mass. Injection molds must have a high precision match between mold halves, so material flow is perfectly controlled. With injection molding, creating the mold is the key to building a perfect, precision part. Injection molding requires a great deal of upfront engineering to develop detailed tooling or molds, so injection mold is much more expensive than blow mold. When the production mold is finalized, and the machine is prepped, manufacturing begins.

Compare with injection molding, the advantages of blow molding are products is stronger, lighter, machine and mold cost are lower, can do Multi-layer, but product precision is not as high as injection molding. Below is a table that lists differences between them.