Blow Moulding or Injection Moulding: Which is Better?

Are you into building products that involve moulded plastic parts? Blow moulding and injection moulding are the two most common ways to produce cost-effective, high-quality plastic parts and derivatives; however, both serve different purposes and have different requirements. So, which one is right for you? To know which one better suits your purpose, first, you need to know the primary difference between them.

Determining if blow moulding or injection moulding is suitable for you begins with understanding the basics. Here’s a quick guide on blow moulding and injection moulding, their differences and their applications.

1)      Different Products

Perhaps the most obvious difference between parts made by blow moulding and parts made by injection moulding is that blow moulding creates hollow parts, while injection moulding produces solid parts. If you’re producing a piece that can be structural, flexible or hold fluid, blow moulding is what you need.  One of the most common examples of blow moulded products is a plastic bottle. Blow moulding can produce a variety of products like fuel tanks, stadium seating, traffic safety products, carrying cases, and children’s outdoor toys.

While injection moulding is perfect for applications that require complex part geometries, tight tolerances, as well as precision repeatability in production. Medical equipment, under-the-hood automotive components, and public & defence safety equipment generally, which need high-performance, high-level engineering, and consistently reliable devices, are constructed using injection moulding.

2)      Different Processes

The blow moulding technique starts with heating up a plastic tube. This tube is then filled with air until it becomes a balloon of hot plastic, known as “parison”. The mould is now clamped around this balloon and traps the plastic while the air fills and stretches the parison into the desired shape. The machinery size and associated costs required to produce blow moulded products are essentially based on the overall weight of the plastic “shot” used in the mould.

On the other hand, injection moulding begins with injecting melted resin into a hollow mould until it is filled. The injection mould is then held together under extreme pressure, adequate for an entire interior part to be occupied with high pressure melted plastic resin. Thus, the cost and size of the machine for producing a product depends on the amount of “tonnage” pressure essential to hold this mould together.

3)      Different Moulds

Blow moulds have more design freedom between each mould halves as each mould half expands to form its own shape. With blow moulding, creating a mould is essential, but other variables like air leaks, wall thinning, flash, and streaks need to be monitored. Time to time monitoring of the manufacturing line is significant for product consistency and quality control. If the plastic is stretched to a greater extent, it can result in thin cracks and small pinholes. Also, monitoring wall thickness uniformity is vital to ensure the correct tolerances for product satisfaction. Providing a solid set of quality control systems is required to produce consistent, high-quality, and functional parts.

On the other hand, injection moulds must have a high precision match amongst mould halves so that material flow is seamlessly controlled. After you have a perfectly functional and error-free mould, the rest of the process must be just a routine. The high precision of an injection mould usually makes it a bit more expensive than a blow mould.

To find out which moulding process is better suits you, contact Awanti Polymoulds, one of the largest mould manufacturers in India. We are the leading blow mould manufacturers in India and a prominent provider of advanced blow moulding technology. We specialize in blow moulds for rotary machines and PET blow moulds. Awanti Polymoulds is known for its commitment to quality products and client satisfaction.