Industry Standards and Specifications
The specifications for materials and properties are published by the American Society for Testing and Materials (ASTM), although other groups such as the Society of Automotive Engineers (SAE) also publish specifications covering these requirements. Standards and tolerances are published by the American National Standards Institute (ANSI) in cooperation with the American Society mechanical engineers (ASME) and the Industrial Fasteners Institute (IFI). Where applicable, published specifications covering a particular attachment will be referenced in the section of this booklet dealing with this attachment. Standard fasteners are basic industrial fasteners, hex bolts, cylinder head bolts, plow bolts, plow bolts, lag bolts, studs, nuts, rivets and others that have been standardized over the years in terms of style, use, properties, dimensions and tolerances. Modern industrial fasteners are manufactured to a variety of standards covering dimensions, tolerances, materials, mechanical properties, tests procedures etc.
Basic Fastener Types:
A bolt is a device with a head at one end of a stem or body and a wire at the other end. Designed to be inserted through the holes in the assembly parts, it is coupled with a threaded nut. The tension is normally induced in the bolt to compress the assembly by rotating the nut. This can also be done by rotating the bolt head.A screw is a bolt with head and thread used without nut. It is inserted into a tapped hole on the inside and the tension is induced by the rotation of the screw head.
A stud is a headless fastener but has threads at both ends of the rod. It has, like a screw, an end that is screwed into a tapped hole. A nut is used at the other end to create a tension.
If a stud is threaded along its length of rod and a nut is used at both ends to create tension, it serves as a bolt and is then classified as a stud bolt.
The diameter of all bolts is measured as the outside of the large diameter of the threads. The length of a bolt with a head is measured from the largest diameter of the bearing surface of the head to the end of the tip in a line parallel to the axis of the bolt. For example, square or hex bolts are measured from the head to the end of the bolt; a bolt with a countersunk head is measured overall. The tip of a bolt is always included in the measured length. Headless fasteners, such as studs, are generally measured, including dots, except for continuous threaded alloy studs to ASTM specification A193. This type is measured from the first thread to the first thread.
HEAVY HEADS AND NUTS
Bolt users may require a larger bolt head or nut to compensate for large clearance in bolt holes or an unusually heavy load. For such needs, we offer heavy bolt heads and nut sizes. Heavy nuts are quite common and readily available in various types and sizes, but heavy bolts have a more limited availability.
BOLT AND NUT BEARING SURFACES
Bolt-on bolts are generally made of stainless steel, but large or very long bolts may have a flat (unmachined) face. Nuts made on cold nuts may have double bevel faces or washers. Large nuts have hot-forged, non-machined washers, unless specially ordered.
CUT VS. ROLLED THREADS
The terms "rolled wire" and "cut wire" refer only to the physical characteristics of commercial bolts or studs, and not to the method of wire production. A threaded bolt has a rod diameter equal to the threaded diameter; a rolled wire bolt has a rod diameter smaller than the threaded diameter.
Basic Fastener Types:
A stud is a headless fastener but has threads at both ends of the rod. It has, like a screw, an end that is screwed into a tapped hole. A nut is used at the other end to create a tension.
If a stud is threaded along its length of rod and a nut is used at both ends to create tension, it serves as a bolt and is then classified as a stud bolt.
The diameter of all bolts is measured as the outside of the large diameter of the threads. The length of a bolt with a head is measured from the largest diameter of the bearing surface of the head to the end of the tip in a line parallel to the axis of the bolt. For example, square or hex bolts are measured from the head to the end of the bolt; a bolt with a countersunk head is measured overall. The tip of a bolt is always included in the measured length. Headless fasteners, such as studs, are generally measured, including dots, except for continuous threaded alloy studs to ASTM specification A193. This type is measured from the first thread to the first thread.
HEAVY HEADS AND NUTS
Bolt users may require a larger bolt head or nut to compensate for large clearance in bolt holes or an unusually heavy load. For such needs, we offer heavy bolt heads and nut sizes. Heavy nuts are quite common and readily available in various types and sizes, but heavy bolts have a more limited availability.
BOLT AND NUT BEARING SURFACES
Bolt-on bolts are generally made of stainless steel, but large or very long bolts may have a flat (unmachined) face. Nuts made on cold nuts may have double bevel faces or washers. Large nuts have hot-forged, non-machined washers, unless specially ordered.
CUT VS. ROLLED THREADS
The terms "rolled wire" and "cut wire" refer only to the physical characteristics of commercial bolts or studs, and not to the method of wire production. A threaded bolt has a rod diameter equal to the threaded diameter; a rolled wire bolt has a rod diameter smaller than the threaded diameter.
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