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.
PTFE (polytetrafluoroethylene) has similar properties to Teflon, including an extremely low coefficient of friction (it doesn't stick to other materials and it resists surface wear). PTFE also exhibits a useful service life from below -100 degrees Fahrenheit, to temperatures of over 500 degrees Fahrenheit. Its resistance to solvents is also excellent throughout a wide range of temperatures. PTFE has a high dielectric strength (600 volts/millimeter) which makes it a good insulator. PTFE is also very non-hydroscopic, or water resistant, absorbing less than 0.01% of its weight if exposed to water for a 24 hour period. PTFE has below average tensile strength, at 3000 psi (pounds per square inch).
Pan head fasteners have a low, large cylindrical head with a high rounded top edge for higher tightening torques - these fasteners are often recommended to replace older head styles such as round, binding, or truss-head where possible. 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.