Blow Moulding Explained

yuAlthough green activism against the usage of polythene-based products like plastics has spread across the world, their relevance in the packaging of different consumer items is growing stronger with each passing day. Evident are the wide range of plastic-based durables like combs, taps, cutlery, domestic and industrial appliances.

There are the examples of bottled products like filtered water in the guise of mineral water, beverages, canned food, edible oils, cosmetics and medicines etc. All these items that are dispensed in the market are an outcome of PET (Poly Ethylene Terephthalate) packaging.

This exclusive mode of packaging is based on the technology of extrusion moulds (spelt as molds in American English). In turn, the blow molding machine manufacturers have risen to the occasion to meet the constant demands in the international markets.

In the first process of extrusion blow molding, the molten plastic forms into a parson, a tubular hollowed piece with a hole in one end for compressed air to pass. This parson is clamped into a mould that is made as per desired design. No sooner than the molten plastic is cooled, it solidifies and the mould opens up to eject it. There are two modes of extrusion blow molding. One of them is constant extrusion of the parson while the other is intermittent.

The continuous extrusion blow moulding can be carried out with two types of systems:

  • Rotary Wheel
  • Shuttle machinery

In the intermittent blow molding process, the operations are carried out either by

  • Reciprocating Screw machinery or
  • Accumulator Head machinery

Almost all the products with hollow features are products of extrusion blow moulding.

The process of extrusion blow molding has certain advantages like low-cost in making of a die, faster rates of production, scope to mould odd and complex designs. In contrast, the disadvantages are designs restricted to only hollow features, low strength and the inability to recycle the multi-layer parson made from different materials.

As for the injection and injection stretch molding, it is the preform that functions.

In this process, there are two types:

  • Single stage
  • Two stage

In the single stage process of injection moulding, there are two types, namely 3-station and 4-station machinery.

The advantages of injection stretch blow molding are that the quantity can be voluminous, least possible restrictions on designs and ample scope for recycling and use on a third application. However, this type of procedure has certain disadvantages like high capital-intensiveness, need for larger shop floor and production being restricted to bottles and phials only.

The manufacturers of blow moulding machinery have proved their versatility in this sector. Different reputed companies across the globe have excelled by catering to the needs of millions of users at home as well as abroad with tailor-made machinery and PET preform of high quality.

Leave a Reply