Injection moulding and blow moulding are two of the most popular ways to produce high-quality, cost-effective plastic parts and products, but both are used for different applications and have different requirements.

Most people in the plastics manufacturing industry are familiar with both techniques, but there is still some confusion by product designers and engineers who are new to the industry as to what the difference is between the two.  Do you know the difference?

Blow moulding

The blow-moulding process begins with melting down the plastic and forming it into a “parison”.  The parison is a tube-like piece of plastic with a hole in one end through which compressed air can pass. The parison is then clamped into a mould and air is blown into it. The air pressure then pushes the plastic out to match the mould. Once the plastic has cooled and hardened, the mould opens up and the part is ejected. Unlike injection moulding, blow moulding makes hollow plastic parts like plastic bottles and containers.

Injection moulding

Injection moulding is used to manufacture parts from thermoplastic materials such as polystyrene.  These thermoplastics, usually plastic polymers that become soft when heated and hard when cooled, can be formed into different shapes once heated then pressurised into a mould for a range of parts.  Injection mouldings usually make solid parts like Frisbees or body panels for cars.

Injection moulding has numerous benefits, including the following:

  • It’s accurate – Injection moulding is such a precise method that it can fabricate almost any type of plastic product. Accuracy is typically within 0.127 mmm.
  • Its fast – While the speed depends on the complexity of the mould itself, generally about 15 to 30 seconds pass between cycle times.
  • Low labour costs – Injection-moulding equipment generally runs with a self-gating, automatic tool to keep operations streamlined and production ongoing, requiring minimal supervision.
  • Flexibility – It is relatively simple to change the type of material being produced as well as the colour the product is being produced.
  • Cheaper than plastic machining, in the long term – The initial creation of the mould can be costly. However, once the mould is created you can create a very large volume of plastic components at minimal cost. For this reason, large production runs using plastic machining can cost up to 25 times more than injection moulding.

Plastic & Chemical Trading (P&CT) are South African experts in the injection-moulding field. Together with their associate KraussMaffei, a world-class leader in moulding, P&CT can offer you the best solution, plant and process development to give you the competitive edge.

Contact Plastic&Chemical Trading for more information on how a KraussMaffei injection-moulding machine can set you apart from the competition not only today, but always – because once you become a member of the P&CT family, you’ll have a partner for life.

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