Composite Material Technology for Structural and Mechanical Applications
An introduction to resin matrix systems, reinforcements, and product forms
What is a composite?
Composite materials are made up of two or more different materials, referred to as the matrix and the reinforcement.
Each combination is chosen for its ability to deliver predictable and repeatable performance to match the application’s requirements. Since these materials have very different properties, the heterogeneity of composites must be addressed to support the analysis of composite parts and structures.
The matrix functions to bind the reinforcement together and protect it. A composite matrix will be one of three types: polymer, metal or ceramic.
Norplex-Micarta specializes in a subset of polymer matrix composites called thermosets. Thermosets undergo a high-temperature curing process by which the chemical structure of the polymer is irreversibly cross-linked. Therefore, thermosets do not melt after curing, as opposed to thermoplastic materials, which do melt.
The reinforcement is considered the primary contributor to the strength and stiffness of the composite. Potential reinforcements that can be effectively utilized are nearly infinite. Common reinforcement materials include paper, cotton fabrics, glass, aramids, nylon and carbon fiber. Other materials such as virgin PTFE or rubber can be incorporated into the composite to achieve specific design objectives.
Norplex-Micarta produces prepreg from several different resin systems such as epoxy, phenolic, melamine, and silicone. These resin systems can be modified through the use of various additives to modify their behavior. These additives can make the material semi to fully conductive, increase the hardness, increase the toughness, or reduce the coefficient of friction, amongst other possible enhancements.
Reinforcements are virtually endless. From the choice of the fiber, to woven, non-woven, and stitched fabrics, and various hybridizations and combinations of the myriad of inputs, designers have a wide range potential inputs that can be used to optimize a material for their specific application.
Prepreg a semi-finished composite.
It is shorthand for “pre-impregnated” and is associated with continuous fiber reinforced materials. Prepregs have the greatest strength to weight ratio of any composite material. This is a result of having the highest fiber volume fraction relative to other composite manufacturing techniques. Being semi-finished, prepregs must be further processed or fabricated into a fully cured state. Many process options are available, each with distinct advantages. These processes include:
- Press Molding
- Various winding processes
- Automated Tape Placement
- Out of Autoclave
In order to successfully process or fabricate a prepreg, any process must create conditions that allow for good consolidation of the material and apply heat in order to initiate and maintain the cure process. Norplex-Micarta produces prepreg in a solution coating process. Compared with other prepreg manufacturing techniques, this method assures even resin impregnation, fast production speeds, and normally results in a tack free prepreg that is well suited for high volume, automated, fabrication.
Norplex-Micarta is always developing new materials.
Many structural applications require a speed of processing that is not achievable in many of the standard composite fabrication techniques, such as autoclave.
Norplex-Micarta is investing in technologies and techniques that allow for the co-curing of prepreg materials with other thermosetting material forms so that near net shape, complex cross section, and mass production targets can be achieved.
Sheet materials are readily available for fabrication into parts.
Manufactured from Norplex-Micarta’s prepregs, sheet products provide unique advantages to designers of composite parts and structures. These include:
- Sheet sizes from 36 inches by 48 inches up to 48 inches by 120 inches
- Thicknesses from 0.010 inches to more than 8 inches
- Easily customized with different surface or core materials, including traditional materials like rubber or metals
- High volume, consistent, and predictable
Sheets can be fabricated using various standard machining and stock removal processes, such as:
- Milling, turning, grinding
- Punching, routing, sanding
- Water jet cutting, shearing, sawing
- Norplex-Micarta is always developing new materials.
Many structural applications require a more complex shape than can be produced from a sheet. Nevertheless, these sheet materials allow for a detailed, yet timely, understanding of various material properties to establish a baseline for design work in other geometries.
Norplex-Micarta has an internal laboratory capabilities and dedicated applications engineers to support designers as they evaluate and select materials and processes to meet the needs of their specific application.
Manufactured from Norplex-Micarta’s prepregs, these products are engineered to meet specific design requirements such as:
- Mechanical strength and stiffness
- Dielectric properties
- Thermal endurance
Like sheet products, these materials can be fabricated with standard stock removal techniques.
Norplex-Micarta is always developing new materials – and new geometries.
Many structural applications require a more complex shape than can be produced economically from a stock shape.