Injection Moulding vs Blow Moulding: Which One To Use

f you’re in the plastics manufacturing sector, you’re probably familiar with both the injection moulding process and the blow moulding process. However, for anyone new to the industry, as well as some product designers and engineers, the distinction between the two can be blurry.

Choosing the wrong manufacturing process can be a huge waste of time and money in terms of prototyping, design and production. And conversely, selecting the right method will speed up production time and cut costs, so you want to be sure you’re choosing the right method every time.

Injection moulding vs blow moulding: what’s the difference?

Injection moulding

Injection moulding is used to make solid plastic items like packaging, bottle caps, Frisbees, car parts and panels, and various components. It’s the most common method used to make plastic items, and there’s no other manufacturing process that provides the same wide range of capabilities that this process does. Check out the video below to understand more about injection moulding.

Blow moulding

Blow moulding is the most popular method of making hollow items out of thermoplastics, like jars and bottles. If you think the process seems familiar, you’re right: it evolved from the ancient practice of blowing glass. There’s a wide range of plastic resins that can be blow moulded, and lots of different ways of doing it. Watch the video below to learn more.

A few more things to consider

In blow moulding, items created may have different thicknesses at different parts, while with injection moulding, the item is the same thickness throughout.

Lastly, bear in mind that in the injection moulding process, making the mould is 90% of the work involved. However, in the blow moulding process, making the mould is only half the work – many other factors come into play, like the type of plastic being used, the temperatures reached during production, the pressure of the air being blown and the mould close speed. This means that blow moulding has the potential to be a lot costlier and more time-consuming than injection moulding.

Affordable plastic injection moulding in South Africa

If you’ve decided to go with injection moulding, we can help. At Plastinternational, we’ve specialised in plastic injection moulding for 30 years, from as little as 0.5g shot weight to over 2kg shot weight. We also offer custom injection moulding and can assist with everything from conceptualisation and design to production and quality control.

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