Closed Mould Composite Manufacturing Processes

 

In recent decades, many industries have increasingly adopted fiber-reinforced composites. These materials are preferred by various industries because of their high strength and lightweight, corrosion resistance, and design flexibility. How these composites are manufactured plays an important role in getting the desired shape and properties. The selection of the manufacturing process largely depends on the materials, the part design, and the end-use or application.

The manufacturing process of composites can be divided into two broad categories-

Open Mould Processes- These involve creating composite parts in an open mould, allowing for easy access to the mould and direct application of composite materials. This manufacturing process is usually used for production parts that have lower tooling costs, need faster production times, and are simple in design. The most common processes are Wet Hand Lay-up, Spray Lay-up, Filament Winding, and Automated Tape Placement.

Closed Mould Processes- These involve manufacturing parts or products in a closed or sealed mould by providing a controlled environment for the curing or solidification of the composite materials. This process has advantages like precise material control, improved mechanical properties, and suitability for producing complex parts. Let us discuss in detail the commonly used closed moulding processes- 

Vacuum Bagging

Vacuum Bagging is a widely used process known for its ability to produce high-quality, consistent, and void-free composite parts. This method is used in the aerospace, automotive, and marine industries, where precision and structural integrity is important.

This process begins by placing dry reinforcement materials like fiberglass or carbon fiber into a mould according to the desired design. A liquid resin is applied to the reinforcement materials. A vacuum bag is placed over the layup, and a vacuum is applied to remove air and excess resin. The bag ensures uniform pressure on the composite, promoting proper resin impregnation. Then the composite is left to cure under controlled conditions, ensuring optimal bonding and mechanical properties. 

Advantages of Vacuum Bagging

Consistency- The vacuum ensures consistent resin distribution, reducing the chances of voids or air pockets.

High-Quality Surface Finish- The process produces parts with a smooth and visually appealing surface finish. 

Complex Shapes- It is versatile and can be applied to produce complex shapes and intricate designs.

Resin Infusion

Resin Infusion is a semi-automated process that offers enhanced control over resin distribution, resulting in composite parts with superior strength and consistency. This method is well-suited for large and complex structures where achieving uniform resin impregnation is crucial.

This process also starts with laying up dry reinforcement materials in a mould.

A dry, porous medium, often referred to as the "infusion mesh," is placed over the reinforcement. This mesh aids in the even distribution of resin. A vacuum bag is then sealed around the mould, creating a controlled environment. Resin Infusion is done into the mould that travels through the infusion mesh, wetting out the reinforcement materials evenly. Finally, the composite is left to cure, ensuring a strong bond between the reinforcement and resin.

Advantages of Resin Infusion

Uniformity- Resin Infusion ensures consistent resin distribution throughout the composite, minimizing variations in mechanical properties.

Reduced Waste- The process allows for precise control of resin volume, minimizing excess and reducing material waste. 

Scalability- Resin Infusion is suitable for both small and large-scale production, making it versatile for various applications.

Resin Transfer Moulding

Resin Transfer Moulding is a closed-mould process that strikes a balance between efficiency and precision. It is particularly suitable for high-volume production of composite components with intricate designs and consistent quality.

This process begins with the closure of the mould, which consists of two halves that form the desired shape of the final product. Liquid resin is injected into the closed mould under low pressure. Then the composite is left to cure within the closed mould, ensuring the formation of a strong and durable part. Once cured, the finished part is demoulded, and excess material is trimmed.

 Advantages of Resin Transfer Moulding

Complex Geometries- Resin Transfer Moulding is ideal for producing parts with intricate designs and complex geometries.

Consistency- The closed-mould system ensures consistent resin impregnation, minimizing variations in part quality.

Cost-Effective- It is a cost-effective solution for high-volume production due to its efficiency and automation.

These manufacturing processes play an important role in the development and innovations in various industries ranging from aerospace to automotive, military to medical, etc. Our team at Datum specializes in using a vast number of different techniques for processing and manufacturing advanced composite materials.