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A clamp nut is a mechanical fastener used to hold two or more mating objects together securely. These nuts are commonly used when a significant amount of force is required to attach the items. Clamp nuts are tightened using a standard adjustable wrench, or ratchet. A torque wrench may be used when a precise amount of clamping force is needed to secure the mechanical connection.
Clamp nuts are typically used in combination with a screw or bolt. The screw, or its externally-threaded portion, consists of a cylindrical shaft with helical grooves that allow the clamp nut to be advanced along the shaft when rotated. A clamp nut can have a cylindrical or hexagonal shape, and a center hole, with the same internal thread as the screw. The bottom surface of a clamp nut is often larger in diameter than the body of the nut, and has a smooth surface. This smoothness provides even contact with the object being secured, to maintain uniform clamping force when the nut is tightened.
The most commonly used clamp nut has a hexagonal profile, to allow the use of a tool for tightening; and a cylindrical bottom portion that applies the clamping force to the objects being secured. This type is used in general-purpose applications that do not require high-precision dimensional tolerances. Locking clamp nuts are also available, and usually consist of a ring that surrounds the nut and progressively tightens on the thread of the screw or bolt. Once tightened, a locking clamp nut will be difficult to loosen without applying very high torque.
Clamp nuts come in many styles and are available in metric and standard sizes. The type and size selected for a specific application often depends on several factors, such as the amount of force required and the environment of use. Clamp nuts are manufactured from a variety of materials, including steel, stainless steel, or brass for corrosion resistance; and metal alloys for high-strength applications. The primary factors to consider when selecting the right material are the forces required, the corrosion resistance needed, exposure to vibration, and the ability to resist chemicals.
Clamp nuts are used in many different applications, including home appliances, automotive engines, and the assembly of high-precision tools and dies. The cost of a clamp nut will depend on its design, the material used, and the level of dimensional tolerances required to meet the end-use requirements.