 NEMA grades X, XX and XXX Paper Reinforced Phenolic - natural color is typically light tan to brown. These grades are composed of a paper base impregnated with a phenolic resin binder. (Phenolics are the oldest, best-known general-purpose thermoset resins. They are among the lowest in cost and easiest to process. Phenolics are quite adequate for a fair percentage of electrical applications. Generally speaking, they are not equivalent to epoxies in resistance to moisture, humidity, dimensional stability, shrinkage and retention of electrical properties in extreme environments.) The paper-reinforced phenolic has good electric strength properties with fair mechanical strength and is outstanding for use as template material and/or backup material. A good rule of thumb in selecting a paper grade is to remember the more X's the better the electrical properties, while the fewer X's represent superior mechanical properties. Paper grades can be modified by adding plasticizers to make them more conducive to part punching resulting in a P suffix added to the X designation, i.e., XP, XXP, XXXP.
Phenolic Cotton Grades of Industrial Laminates
NEMA grades C and CE canvas Cotton-Cloth Reinforced Phenolic - natural color is typically light tan to brown. These grades are composed of a continuous cotton woven cloth impregnated with a phenolic resin binder. (Phenolics are the oldest, best-known general-purpose thermoset resins. They are among the lowest cost and easiest to process. Phenolics are quite adequate for a fair percentage of electrical applications. Generally speaking, they are not equivalent to epoxies in resistance to moisture, humidity, dimensional stability, shrinkage and retention of electrical properties in extreme environments.) These grades contain a medium weave canvas and are known primarily for their mechanical properties. These grades are not recommended for primary electrical insulation.
NEMA grades L and LE Linen Cotton-Cloth Reinforced Phenolic - natural color is typical light tan to brown. These grades are composed of a continuous cotton woven cloth impregnated with a phenolic resin binder. These grades contain a fine weave linen and, like the canvas phenolic, are known for their mechanical properties. The finer weave allows for machining more intricate details than canvas grade, such as gear teeth, etc. These grades are not recommended for primary electrical insulation but grade LE exhibits superior moisture resistance to grades L, C, and CE and thus is an adequate insulator for a fair number of applications.
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