What You Need to Know About the Bladder Molding Process

Bladder Molding Process

Do you manufacture complex hollow composite parts? Then improving the bladder molding process is something that might be of interest to you.

Are you familiar with the Bladder Assisted Composite Manufacturing (BACM) technique? And how it has made improvements to the conventional bladder molding process?

If you are not, yet, you should know that the improvement is not only in the process. It is also in the output and quality of the part produced.

You want to improve the process and quality of the parts or products you produce. Your company wants to stay in front of its business sector, to see how, please read on to find out more.

So What is The Bladder Molding Process

It all begins with sheets of fibers impregnated with a special resin, also known as “pre-preg.”

Once we have the “pre-preg” sheets, they wrap them around an inflatable bladder. And then they place them inside of a mold cavity.

The next step is they close the mold. Once closed in the mold, it will apply pressure to the inside of the bladder.

Pressure will cause the bladder to expand, and it will push on the resin-filled fibers. The pressure pushes outward against the inside of the mold cavity.

Then they apply heat to the mold to solidify the part, or also known as curing. The component fibers form in the shape of the inside the mold cavity.

Once cured they open the mold revealing the hardened hollow part. After, removing the bladder from the inside piece.

Future of Bladder Molding Technology

The bladder assisted composition manufacturing technique has produced aerospace quality components. It eliminates disadvantages compared to conventional bladder molding applications.

The conventional bladder molding method is often the only reliable process. It is a process to make components that have complex geometry. But not axis-symmetric and varying wall thickness components.

The bladder molding process has advantages but is often overlooked. It gets ignored because it requires the use of an autoclave or oven to cure the part.

BACM has advantages over conventional bladder molding applications. It is because it heats the component from the inside during the curing process. It can control cure pressure and resin outflow.

The fiber volume contents have been very high compared to conventional bladder molding. Void content has been almost indistinguishable compared to conventional bladder molding techniques. The process reduced the energy required by over half.

The BACM technique has feasibility for current fabrication methods. This method is for the production of components with varying geometric complexity.

Further development has allowed the fabrication of large hollow structures. Structures like plane wings and fuselages are very promising.

Composite Manufacturing Using Bladder Technology

Hollow composite components get manufactured with the use of expandable bladders. In the bladder molding, manufacturers use a bladder whose geometry is close to the shape of the inside of the part.

During the set up dry or impregnated fabric gets draped around the inflatable bladder. Then the laminate gets placed in the bladder and gets inflated to the desired pressure. The mold is then heated to enable the part to cure.

There are advantages to using an inflatable bladder instead of the expandable bladder. Parts get fabricated using pre-impregnated or dry fibers. The dry fibers get impregnated with resin transfer molding.

Pressure variance is independent of the temperature used to cure. The disadvantage is that they need an oven or autoclave. There is some complex tooling for bladder molding that may need embedded heaters.

Inflatable bladder molding is more attractive for commercial uses because of its versatility. The ability to fabricate parts using either pre-impregnated or dry impregnated carbon fibers.

Automotive Structures

Bladder molding is for major automotive parts that include hollow areas. Cost-effective solutions for parts made with the use of a bladder RTM (resin transfer molding) process called crossbeams.

Bladder molding is one of the most available technologies for composite parts that have complex shapes like parts that have hollow areas and high fiber content.

Bladder molding will reduce the number of tools and steps required to manufacture the part — bladder RTM technology for the manufacture of hollow parts.

Mechanical Strength and Durability

Today the use of parts with high fiber content that provides high mechanical strength and is lightweight is an expectation. You will find these kinds of pieces in an automobile from the tailgate to the engine.

It is what has driven the improved gas mileage that many cars and SUV’s can produce today.

Military applications must meet a higher standard of performance and reliability. These applications are put to use through harsh environments.

Bladder molding has made the replacement of complex parts possible. All this without compromising the strength or functionality.

High Tech Composite Engineering for Several Industries

Bladder molding has enabled composite manufacturing to strengthen components with carbon fibers.

Aerospace, defense, automotive, medical and sports and recreation have all found ways to improve their respective industries.

They have taken advantage of composite engineering. The technology that has allowed companies to replace metal with an equal or better composite part.

Other applications such as wind-generated energy have found ways to improve the blades for the turbines.

It has allowed them to make the blades longer. Longer blades have turned the already environmentally friendly wind turbine into an even more efficient source of energy generation.

Composite parts are to make the vehicle lighter and more fuel-efficient. But where will composite engineering lead to next? Will we have a composite engine block someday?

It seems that the sky is the limit when it comes to composite molding and what it can produce. How composite parts can change an industry seems more real when you consider that this technology has been around for thousands of years.

From the 1200s where Mongols made composite bows from wood, bone, and tendons. To the 2000s where thermoplastics like PVD have expanded the use of composites in the automotive and consumer product industries.

Improving your existing product lines and components start with the right partner. You can find the right partner by contacting SMI today.

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