Blow molding, also known as hollow blow molding, is a method that uses gas pressure to inflate a molten plastic parison clamped inside a mold to form hollow products.
There are three main processes of blow molding, namely injection blow molding, extrusion blow molding, and stretch blow molding.
Blow molding is characterized by lower equipment costs, strong adaptability, and good molding status, and can be used to create products with complex curves.
Plastic blow molding refers to the process where molten plastic is formed into a tubular parison through extrusion or injection, and then inflated into the desired shape within the mold using compressed air.
Raw Material Preparation
Choose suitable plastic materials such as PE, PET, etc.
Heating and Melting
Heat the raw material to a molten state.
Forming Parison
Form a tubular parison through extrusion or injection.
Inflation Molding
Place the parison in the mold and inflate it with compressed air to form.
Cooling and Shaping
Cool the mold to shape the plastic product.
Demolding
Remove the formed plastic product from the mold.
Plastic melts at high temperature, molecular chains move more vigorously, and fluidity increases. For example, PE melts around 180°C.
Extrusion Molding
The molten plastic is extruded into a tubular shape through an extruder.
Injection Molding
The molten plastic is injected into a tubular shape using an injection machine.
Compressed air enters the parison interior through the mandrel, causing it to expand evenly and fit closely to the mold wall.
The cooling system quickly cools and shapes the plastic product through the mold's cooling channels.
Uneven Wall Thickness
Adjust the inflation pressure and parison temperature.
Surface Defects
Check the mold surface finish and raw material quality.
Taking PET bottle production as an example:
Raw Material: PET resin.
Melting Temperature: 280°C.
Inflation Pressure: 10-15MPa.
Cooling Time: 10-15 seconds.
