Bolt

See also: Bolt (homonymy)

A bolt is a body of assembly made up of a Vis and a nut (and possibly of a Rondelle).

Attention! This definition does not correspond to the uses in other languages, in particular English, or roughly speaking , the screw is called " bolt" when it is associated with a nut - this nut not forming part of the bolt (nut & bolt), as it is the case in French.

Let us note just as in nuts and bolts the screw term corresponds to a complete Filetage whereas the correct term is body of bolt when the threaded part is partial. For example a bolt hexagonal head corresponds to the standard ISO 4014 if threading is partial and to standard 4017 if threading is complete (under head).

A bolt creates a connection supplements, rigid and dismountable , between the parts which it crosses and presses one against the other. In fact, the bolts (and machine screws) act as of the very stiff springs whose elasticity makes it possible to maintain the work-holding in spite of the influence of external factors such as mechanical actions, vibrations or of the rises in temperature. One or more Rondelle S placed on both sides of the parts makes it possible to better distribute the compressive force, to take again the possible mattage of surface and/or to protect the substrate from nondesired deformations. An additional nut ( counter-nut ) can come to slow down the assembly and to prevent that it is loosened. The name of bolt integrates by extension this complementary equipment.

The bolt is a device of prestressed Assemblage. Indeed, the motor traction maintained in the stem causes a friction which prevents the rotation of the head of the screw and that of the nut compared to the fixed part. Since this tension disappears (Flatness of the surface of contact in + 15 min, creep in + 10 years), the assembly perishes.

Various devices make it possible to avoid the loosening of the nut, by mechanical stop (discs to be folded back, drilling and passage of a wire in aviation, goupillage, castellated nuts), or by effect of tightening in particular the lock washers split and rubber bands (" GROWER" or " W"), undulated, notched (" EVENTAIL" or " AZ"), by braking of the nut itself (nylstop self-locking nuts, with flange); the modern tendency being to joining by anaerobic, dismountable adhesives by heating or rough force.

The characteristics of definition of a bolt are:

those of its stem:

form of head: hexagonal, square, cylindrical, milled, six hollow sides, diamand, halfen…
installation of the head, dependant on the system of operation: slit, print, etc (for screwdriver, hexagonal wrench…)
length of stem and threaded length (defined by the standards),

those of its nut:

form (hexagonal by defect),
height.

those common to both:

nominal diameter of threading,
profile of the net and not of screw,
matter (E36 steel, E24, 35CD4… Stainless, Alluminium, Platinum…)
class of materials (criteria of resistance: classify 4.6,5.8,6.8,8.8,10.9,12.9, A70…).
coating -- only for the steel bolts -- (galvanized hot with soaked, éléctrozingué, dichromate, gross…)

Example of designation: Bolt CHc M8x1-50, 8.8 Zn

The coating and the matter of the bolt play a very important part because of the electochimic couples put in plays.

Eye eye bolt

The head of the screw is a " tranche" of sphere, opening perpendicular to the general axis of the screw, and the nut is often a knurled nut. This bolt is generally used for fast assembly-disassemblings and with the hand, the head of screw being simply committed on a measuring rod.

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