Autoclave Composite Molding for Stronger
and Denser Materials
by dewi susanti
Autoclave composite molding has long been used in the aerospace industry. This specialized fabrication technique produces materials that display greater strength and higher density and hence, fit the bill as construction material for aircrafts, missiles and spacecrafts. The high heat and pressure used in curing materials allows for the creation of quality building materials at a lower cost.
What is an Autoclave Composite?
In order to understand the molding process, one must first be able to explain what composite materials actually are. Composites are compounds of two or more constituent materials combined to form a new material. This new material is better in strength, shape and appearance than its individual constituents put together. The physical and chemical properties of the individual components are different from the properties of the final product. Also, the components remain distinct and separate in the final product.
A Walk-through of the Autoclave Composite Molding Process
1. Shape and Load Capacity:
Autoclave molding is an advanced version of two other composite production processes namely vacuum bag and pressure bag molding. The autoclaves used in the manufacture of composite materials are of a larger size than their counterparts used at medical and research centers to sterilize equipment. Constructed of welded steel, they are typically cylindrical in shape and capable of supporting parts as big as 7 ft in diameter and 20 ft in length; a few models have a larger capacity for example those used to make parts of spacecrafts can be almost 160ft long.
2. Internal Structure:
The heated pressure vessel has a two-sided mold that helps form the two surfaces of the panel. The lower side of the mold is a solid, rigid one while the upper side is flexible. This membrane is made either of silicone or an extruded polymer film like nylon. The fabric of the reinforcement material is laid out inside the autoclave. The reinforcement material is what gives the fiber its strength and stiffness. It can be done manually or can be automated with the use of robots.
Inside the autoclave, the material is subjected to a vacuum, high heat and high pressure. The temperature inside the curing oven ranges between 400 F and 750 F while the pressure between 50 and 100psi (pounds per square inch). The temperature and pressure settings are specific to the individual constituent materials, the product being produced and the desired material characteristics.
The heat and pressure applied kind of hand-rolls the matrix to get rid of air pockets and excess resin. Prior to placing the fibers in the oven, the fibers are pre-impregnated that is the reinforcement material is saturated with synthetic resin. The procedure takes a few hours to complete. The production cycle depends on the ability of the device to transfer thermal energy to the load.
Applications of Autoclave Composites
Autoclave composite molding creates a material with a high strength to weight ratio. As such, they are used in very demanding industries such as aerospace and automotives where there is a need for high quality requirements of composite materials. It is also used in the production of sports equipment such as golf clubs, racquets and snow skis. In the medical field, they are used to create artificial limbs and prosthetic devices.
The precise control of temperature and pressure within an autoclave creates extremely high quality autoclave composite products. They boast of physical and chemical properties not found in its raw materials. They are light weight and of greater strength. They also display a specific type of rigidity. They are also less expensive than traditional materials making it a suitable option for many industries.
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