Bolts are basic fasteners used in industry and construction. The most popular materials from which they are made are carbon steel, A2 stainless steel and A4 acid-resistant steel. There are also screws made of e.g. brass, 25CrMo4 and polyamide. In addition to bolts with standard threads, our offer also includes bolts with fine, inch and trapezoidal threads.
Our regular offer includes plain surface bolts (without coating), electro-galvanized (Zn) or hot-dip galvanized (tZn) bolts - intended for structures requiring higher corrosion resistance. In addition, there is zinc flake coating (dacromet, geomet), as well as nickel-plated and blackened / oxidized coatings. For steel constructions, we recommend HV products or SB sets.
Due to the variety of bolt applications, we distinguish many varieties, which are included in PN, DIN and ISO standards. The differentiation of the screws depends, among others, on on the shape of the head, shaft or end of the screw. Due to the indicated parameters, we distinguish the most popular types of screws:
a) with a head:
- hexagon head DIN 931, DIN 933,
- square head PN 82121,
- mushroom head DIN 603,
- button head ISO 7380,
- t-head DIN 186,
- cylinder head DIN 6912,
- countersunk head DIN 605,
- eye-head DIN 444, 580
- wing head DIN 316.
b) with thread of:
- full length,
- partial length.
The basic parameters used to determine the strength class of the bolt are the tensile strength and yield point of the bolt material. The most common bolts are in four basic mechanical property classes: 5.8, 8.8, 10.9 and 12.9. In general, however, we distinguish as many as 10 classes of mechanical properties of screws. As a class grows, so does its strength. Each bolt is marked with its grade on the head.
Appropriate grades of steel are used to achieve the necessary strength properties.
- class 3.6 - low carbon steel,
- class 4.6, 4.8 - low or medium carbon steel,
- class 5.6, 5.8, 6.6, 6.8 - medium carbon steel,
- class 8.8 - low-carbon steel with alloying elements (B, Mn, Cr), hardened and tempered, or medium carbon steel, hardened and tempered,
- class 10.9 - low-carbon steel with an alloying addition (B, Mn, Cr), hardened and tempered, medium-carbon steel hardened and tempered, and low-alloy steel,
- class 12.9 - low-alloy steel.
