A bolt is used in conjunction with a nut and often washers to hold two objects together. As the nut is tightened along the thread of the bolt, the bolt stretches and applies a clamping force on the two objects holding them together. Over tightening the nut can cause the thread to strip and tightening torques can vary slightly depending upon the application. Consideration should also be given to the shear and yield stress that will be applied by the objects when choosing the type and size of bolt required.
Bolts are measured by their shank diameter and shank length from under the head and are available in a number of different thread types including UNC, UNF, BSF, BSW and Metric.
Hex Head Bolts (also know as Engineers Bolts) have a hexagonal head and depending on the length and diameter, will have a plain shank between the base of the head and where the thread begins. Hex Head Setscrews can be described as a fully threaded bolt, meaning its thread begins under the hex head and is continuous along the full shank of the bolt.
Coach Bolts or Carriage Bolts have a mushroom head (low dome) with a square collar which can be placed inside a recess or will bite into the object being clamped to aid tightening the nut. Often used to hold framing type timber together, particularly where a decorative finish is required or where the head side is in a heavy foot traffic area to reduce personal injury caused by rubbing past a protruding head i.e. decks, railings and steps.
Lubricated Bolts (Moly Bond). The molybond coating system provides a durable barrier coating which is bonded to the surface. During the coating process an inert, durable barrier is bonded to the surface of the substrate. This barrier is resistant to corrosion and chemical attack and prevents electrochemical corrosion.
JCB Bolts or Joint Connector Bolts are commonly used in the construction of kit-set furniture such as bunk beds. Their low profile head and allen key drive providing a tidy finish in conjunction with the JCB Barrel Nuts. Only available in M6 and a range of lengths.
Bolts can be produced in all types of material and Anzor Fasteners carry a wide range of sizes in Stainless Steel 304, 316, Bumax (high strength) grades and also in Galvanized steel. Bolts generally have an industrial looking hex head which may not be suitable for some applications where appearance is important. For these applications you may wish to consider the Coach Bolt, Button Socket Screws, Pan or Countersunk Head Machine Screws. Bolts however are commonly available in a wide range of sizes and are commonly used in the engineering, marine and building and construction industries. A torque wrench maybe required to avoid over or under tightening, but bolts can be assembled by hand with the use of a crescent or spanner.
To avoid galling of the thread on installation the use of lubricant such as Nickel Anti Seize or a lanolin based product is recommended. For Australian customers - see also Stainless Steel Bolts Australia , Stainless Steel Coachbolts Australia
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