Blow Molding Process

Blow molding products

Blow molding is used to make simple parts like plastic bottles, containers, tanks in very high volumes at very low cost. There are three types of blow moldings as follows,

1. Extrusion Blow molding

Extrusion blow molding

This method is generally used to manufacture Plastic bottles of various shapes of from the volume of 10 ml   to 10000 l. This is very simple method compared to the others. This method can be used to process different types of plastics like HDPE, PET, PP and PVC.

The steps of the extrusion blow molding process are,

• The melted polymer is extruded as a hollow pipe which is known as Parison
• Then Parison is clamped in to the bow mold
• Then Parison is blown inside a mold using the air blasting
• Then cooling and ejection is done

2. Injection Blow molding

Injection blow molding

Injection blow molding is used for the production of hollow objects in large quantities with volumes in a range from 10 ml to 100 l. Generally bottles, jars and other containers are manufactured using this method. The appearance and the dimensional quality are higher when compared with the extrusion blow molding.

The steps of the extrusion blow molding process are,

• The melted polymer is injected in to the cavity after the core is inserted
• Then the core is moved in to the mold and the Blowing done using air
• After the cooling mold the ejection is done

3. Stretched Blow molding

This method is used for producing high quality containers. Generally pet bottles which are used to store water and beverages are manufactured by stretch blow molding.

The steps of the stretch blow molding process are,

• The melted polymer is injected in to the cavity as in injection blow molding
• Then Conditioning is done, that mean heated it up to the required temperature.
• Then it is inserted in to the mold and Stretching and Blowing is done at the same time

Stretching blow molding

• After cooling the discharge is done.