Differences Between Injection Mold And Blow Mold

The main difference is that injection Moulding will include the shape of both sides of the piece being molded. The exterior shape and the interior shape. So the plastic fills the gap left between the two pieces.

However the blow molding will comprise just the outer shape of the object. That is because the plastic being molded is a thin tube of plastic (aparison) that gets trapped inside the mold and inflated until it fills the mold. So the interior wall matches the shape of the exterior wall by virtue of air pressure. In other words the interior shape of the mold is created by air pressure from the shape of the outer mold. It's like blowing up a balloon of molten plastic to fill a mold. As opposed to feeding plastic into a ballon shaped gap between two solid peices of metal shapes like the interior and exterior of a balloon.

Injection moulding

In Injection Moulding, melted plastic is forced into a mould cavity. Once cooled, the mould can be removed. This plastic moulding process is commonly used in mass-production or prototyping of a product. Injection moulding machines were made in the 1930’s. These can be used to mass produce toys, kitchen utensils, bottle caps, and cell phone stands are few products made by the help of Injection moulding.

Blow moulding

The blow moulding will comprise just the outer shape of the object. That is because the plastic being moulded is a thin tube of plastic (aparison) that gets trapped inside the mould and inflated until it fills the mould. So, the interior wall matches the shape of the exterior wall by virtue of air pressure. In other words, the interior shape of the mould is created by air pressure from the shape of the outer mould. It's like blowing up a balloon of molten plastic to fill a mould. As opposed to feeding plastic into a balloon shaped gap between two solid pieces of metal shapes like the interior and exterior of a balloon.