Machine Screws, also referred to as Machine Bolts, are often used with nuts or driven into tapped holes. They come in a variety of head types and drive styles, but are generally available in smaller sizes.
Vespel is a high performance polyimide material, which can operate continuously from cryogenic temperatures to 550 degrees Fahrenheit, with excursions to 900 degrees Fahrenheit. Vespel parts exhibit superior performance in a variety of applications requiring low wear and long life in severe environments. Vespel, unlike most plastics, is non-flammable. Parts perform without melting or softening, and resist radiation sterilization more effectively than most other plastics. Vespel parts exhibit a very low level of outgassing, even in high vacuum environments, and are chemically compatible with most fuels, solvents, lubricants and hydraulic fluids. Vespel has above average tensile strength for a polymer, at 12,600 psi (pounds per square inch). Vespel will absorb 0.24% of its weight when exposed to water for 24 hours. Vespel is extremely impact resistant, rated at 14 foot pounds (on the Izod Impact Scale), which compares favorably against Nylon 6/6 at 3 foot pounds. Vespel also has excellent insulating properties, measured in terms of dielectric strength, with a rating of 260 volts/millimeter.
Flat head fasteners are designed to fit flush to the surface when used with countersunk holes. Length is measured from the top of the head. Common applications for slotted screws include woodworking, although the drive style is not designed to be used with power drivers.
A threaded fastener's size name includes information about the major external diameter, followed by the threads per inch, which indicates if it is coarse or fine.