A Walk Through Plastic Blow Moulding Techniques

In today’s age plastic is seen everywhere- be it interiors, packaging industry, medical world or even the world of kitchen utensils. Plastic is a non-metallic substance that can easily be moulded into desired shape. It can be melted and then cooled down into the required structure for commercial use. Even the keyboard that you type on or the mobile that you utilise are made up of plastic.

The basic concept of plastic moulding is very simple. Plastic is melted and the molten plastic is poured in the ready moulds of the desired shape and then it is allowed to cool.

Blow Moulding

In this process the raw plastic is poured in a hollow tube shape with one open end called Parison.  The tube, through its open end is then pressed and the metal mould cooled and the pressurised air is forced into the tube. When the plastic cools the metal mould expands and throws out the product.

Types of Blow Moulding

  1. Injection Blow Moulding

The molten plastic is filled into a mould where it is injected through a nozzle into a hollow mould that forms the external shape of the object. The mould opens and the center rod is rotated and it opens and allows the compressed air into the mould, this exercise inflates the finished object which is then ejected and after cooling. This method is majorly utilized for production of large quantities of hollow objects such bottles or jars.

  1. Extrusion Moulding

In this process the plastic is melted and the molten plastic is poured on a hollow parison. The parison is then closed to capture the melted plastic and air is blown through it so that the molten plastic inflates to the desired shape. After this step the plastic is allowed to cool and later excluded from the Parison. There are two types of extrusion moulding – continuous extrusion moulding and intermittent extrusion moulding. In continuous method the parison is continuously removed and then the individual parts are cut with a knife. In intermittent extrusion moulding parison is not continuously extruded, the new parison is fed only after the existing parison is extruded.

  1. Injection Stretch Blow Moulding

In Injection Stretch Blow Moulding initially the molten plastic is moulded into solid preform and cooled down. This cooled preform is filled into stretch blow mould machines. The preform is then heated again and filled into the plastic bottles with forced air (compressed). Basically this method consists of both injection moulding process and blow moulding process.

We at Awanti specialise in manufacturing the mould required for stretch blow moulding. Precise machining is done on high quality metal to make the mould suitable for world-class blow moulding machines. The result is – millions of bottles with the same level of accuracy are produced from a single mould!

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