Bolt weight table: M5, M6, M8, M10 and M12

One of the most common fasteners found everywhere in the objects around us is the bolt. Bolts can be very diverse; they may be hidden inside floors and walls or remain visible, connecting parts of different structures. The variety of bolt shapes and applications is very large. Below is a more detailed look at the classification of these metal fasteners and their most popular types.

Characteristics

By definition, a bolt is a metal connecting product consisting of a head and a cylindrical shank with external thread. A bolt is fastened by means of a nut or a special fastening element, for example in anchor bolts. The connection type is detachable.

Bolts with a hexagonal wrench head are the most popular. This is the so-called classic bolt. Countersunk bolts are also widely used. Fasteners are classified by the following principles:

• by purpose: furniture bolts, plow bolts for agricultural machinery, road bolts for fences and metal structures, machine-building bolts;

• by material used: ordinary steels, carbon steels, alloyed and low-alloyed steels, heat-resistant steels, copper, titanium;

• by strength and accuracy class;

• by coating.

Depending on purpose and tasks, bolts may have different head shapes. These include swing bolts, anchor or foundation bolts, eye bolts, bolts with a hexagonal or multi-sided head, and bolts with a round or countersunk head.

• Hex bolts are the most common bolts and are sold in any construction and home repair store. A hex-head bolt is designed to fasten parts through through-holes using a nut and wrench. Applications include mechanical engineering, construction and other fields.

• A bolt with a round head is used in furniture production. It securely fastens structural furniture elements, has an attractive appearance, and is made of stainless steel or zinc-coated steel.

• Anchors are intended for fastening floor slabs, installing door or window blocks, suspended ceiling structures and other structures. They are made of stainless steel for installation in hollow and porous materials, although they can also be used for solid materials.

• An eye bolt is a specialized fastener with a ring-shaped head. It may have a hexagonal base or a hinged connection. It is used in systems involving ropes and chain channels. The material is alloy steel. Because of its special strength and reliability, its field of use is very wide, from apartment repairs to shipbuilding and railway line installation.

• A countersunk bolt is used in mechanical engineering and furniture production when working with natural wood and metal. It is effective and makes it possible to visually hide the joint locations.

Other types may also occur, such as anchor bolts with a countersunk head or ring, hook, spherical head, fork head, round head with a hole and others.

Important bolt classification parameters are shank shape and thread pitch. Shanks may have the same diameter along the entire length or combine two stepped sizes, where the smaller part has a thread and the larger upper part is smooth.

Thread type may be metric, pipe, inch, trapezoidal, buttress, square or rectangular. Thread pitch may be coarse or fine.

The GOST standards followed by manufacturers in the production of fasteners may specify the bolt version. These can include additional locking options for the threaded joint or additional slots in the head to reduce bolt weight.

Bolt Weight

When buying a large quantity of fasteners, a store does not count each item but sells them by weight. To understand how many bolts have been weighed out, it is necessary to know how much one piece weighs.

The most popular fastener of this type is a hex-head bolt manufactured according to interstate GOST 7798-70. It has accuracy class B and full thread.

Examples of minimum-length bolt weights for different nominal diameters:

• an M10 by 10 bolt weighs 16.68 g, with 60 pcs in 1 kg;

• an M16 by 18 bolt weighs 65.54 g, with 15 pcs in 1 kg;

• an M24 by 32 bolt weighs 237 g, with 4 pcs in 1 kg.

Brief Decoding of Main Designations

Any fastener has its own designation consisting of a set of letters and numbers that may seem unclear at first glance. The designation can include:

• fastener name: bolt;

• accuracy class: A, B, C, where A is the most accurate; it is specified if there is no further reference to GOST;

• bolt version, meaning special design features, from 1 to 4;

• thread type: M for metric, K for conical, Tr for trapezoidal;

• thread diameter in mm;

• thread pitch, specified only for a fine pitch of a particular diameter;

• thread direction, specified only for left-hand thread because right-hand is standard;

• thread accuracy level 4-8, from precise to coarse;

• fastener length in mm;

• strength class;

• indication of the alloy used;

• conventional coating type designation, from 1 to 13;

• coating thickness in microns;

• production standard type.

Product marking contains the material strength class, the manufacturer’s mark and the thread direction arrow. The strength class is defined by numbers. The first shows the maximum load, and the second shows the ratio between yield and strength indicators.