Bultarna

Bultarna is the definite plural form of bult, the Swedish word for bolts. In mechanical engineering, bolts are fasteners with an externally threaded shaft and a head, designed to be used with a nut and often a washer to secure two or more parts together. They are inserted through aligned holes and tightened to a specified preload, creating clamping force.

Bultarna come in many sizes and shapes. Head styles include hexagonal, socket, button and carriage; thread forms include metric coarse and fine, and imperial UNC/UNF. Lengths, diameters and tolerances vary to fit different assemblies and load conditions. The choice of bolt depends on the required strength, environment, and assembly method.

Materials and finishes: carbon steel bolts are common, with stainless steel and alloy steels used for higher strength or corrosion resistance. Finishes such as zinc plating, galvanizing, black oxide, or specialized coatings improve durability and reduce friction in specific applications. Standards and specifications for bolts are provided by organizations such as ISO, DIN, and ANSI/ASME, and often specify tolerances, mechanical properties, and testing requirements.

Applications and installation: bolts are used across construction, machinery, automotive, and consumer products. Correct selection depends on load type (tension, shear), environment, and compatibility with nuts, washers, and lubricants. Proper installation practices include achieving the correct preload, using appropriate lubrication, and following torque recommendations. In Swedish technical contexts, bultarna may refer to bolts in general, with terminology and specifications adapting to the industry and region.