The Nut is the component of a fastening arrangement with a female thread (on the inside). It normally has some shape or form on the outside to assist in rotating it so that it will tighten on its mating male part. The thread is termed as right handed where the rotation to fasten the nut is clockwise in direction, this is the most common thread type. Some nuts are available that are tightened in the opposite direction and are called left-hand. Nuts come in many various shapes, sizes, grades and types. Following is a list of Types, Grades, Sizes and Uses for the different categories of Nuts.
Hexagon Nuts or Hex Nuts these would be by far the most commonly used nut for all types of fastenings. They are available in many thread types; both metric coarse (standard) and metric fine threads, Unified National Coarse (UNC), Unified National Fine (UNF) and British Standard Whitworth (BSW). Metric sizes are made to the Din 934 standard. They also come in both 316 (also known as A4) and 304 (also known as A2 or 18-8) grades with different tensile strength options.
Nyloc Nuts are similar and complimentary to the hexagon range. The major difference being the nylon ring inserted at the end of the nut. This is a self-locking device to stop the nut undoing under constant vibration or load variations. It is not suitable for use where the temperature is liable to exceed 120 degrees Celsius. For uses where high temperatures are incurred a range of spring metal lock nuts are available in 304 grade only. Metric sizes are made to the Din 985 standard.
Dome Nuts also known as Acorn Nuts, come in two styles, one piece and two piece. A one piece Done Nut is made from a solid piece of stainless and the two piece is a hexagon nut with a dome cap fused to one end. The 2 piece Dome nuts are made with a high-polish finish. The 1 piece Dome nut is made to the Din 1587 standard. Dome Nuts are sometimes known as Cap Nuts and Acorn Nuts.
Lock Nuts, Half Nuts or Jam Nuts as they are sometimes called are used under a Hex Nut or another Lock Nut to lock the fastening and stop it from undoing. They are similar to a Hex Nut but not as high and in metric sizes are made to the Din 439 standard.
Wing Nuts; the range and grades are similar to the hexagon nuts. These nuts are used in situations where a fastening is often undone and done up but does not require an over tight fitting. The pressure that can be exerted by your fingers is sufficient to hold the fastening.
Hank Bushes are internally threaded but with a round outside and with a small reduced diameter shoulder. Designed for welding into sheet metal fabrications so that a fastening can be used to hold firmly in the sheet product. Small range of 304 grade in metric from M3 to M12 and 3/16 to 5/16 in UNC.
Coupling Nuts are very long hexagon nuts that are used to join two long threads together. They are made to the Din 6334 standard.
Flange Nuts are used mainly on concrete retaining type fastenings and automotive / sheet metal fabrications. Small range of metric M4 to M10 and only in 304 grade Tee Nuts are made from a sheet metal punching and are designed so that the 4 prongs and the body come through from the back of timber and hold to stop the nut from rotating. They are mainly used in furniture / upholstery work. The range includes both metric M6 and UNC 3/16 to 5/16 in 304 grade.
Barrel Nuts have a long internal female thread and one end closed with a drive. Either Philips, Slot or Socket.
Bumax Nuts are a range of higher tensile Stainless Steel hexagon nuts.
For Australian customers - see also Stainless Steel Nuts