The Inflatable Bladder Molding Composite Method

The Inflatable Bladder Molding Composite Method

Composite materials have been in use for thousands of years, with the first use believed to be by the Mesopotamians around 3400 BCE.

Composites have come a long way since then. They provide various advantages that make them ideal for a range of applications. There are also various methods that can be used to create composite material parts.

One of the most useful methods is inflatable bladder composite molding. We use this at SMI Composite to make accurate, reliable parts for various industries. But what is it exactly?

In this guide, we’ll cover everything you need to know about bladder-assisted resin transfer molding. Keep reading for more.

What Is an Inflatable Bladder?

An inflatable bladder is used inside a mold to manufacture parts. As it expands, it fills out the shape of the mold, allowing you to manufacture parts in a range of shapes and designs.

The Bladder Molding Method

The bladder-assisted composite manufacturing (BACM) technique starts with pre-preg. This involves impregnating sheets of fibers with a specialized resin. We then place this inside a mold for the desired part and seal it.

We apply pressure to the inside of the bladder. This pressure inflates the bladder, causing it to push against the surface of the mold. After applying heat, the composite sheets will solidify and hold their shape.

Once cutting is finished, we can open the mold and remove the bladder. The resin will have combined with the composite sheets to create a solid part.

To ensure the process is effective, we use compression bladders that have a geometry that’s close to the inside of the mold. It’s worth noting that inflatable bladder molding requires specialized equipment including an oven or autoclave. Fortunately, and SMI Composites we have everything we need for the process.


Composite materials play an important role in a range of industries. The automotive industry, for example, uses it to produce hollow parts. They’re accurate and lightweight, which makes vehicles more fuel efficient.

It’s cost-effective and reliable, especially when it comes to complex parts. The process is very streamlined, with few tools or steps required. This makes it ideal for mass production of components.

It’s used similarly in the aerospace industry to produce aircraft parts. Composite materials typically have a good strength-to-weight ratio, which is ideal for aircraft.

The process has proved itself an environmentally friendly solution as it has helped produce longer, more effective wind turbine blades. There are also various uses of inflatable bladder molding in the sports, medical, and defense industries.

The Right Process for You

Inflatable bladder molding can be very useful, but it isn’t always the best technique. It all depends on the particular part and application.

If you want to find out if it’s right for you, the team at SMI Composites can help. We have years of experience, so we’ll be able to discuss your needs and recommend whether you should go for inflatable bladder molding or a different technique. Contact us today and we can figure out the best solution for you.

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