Screws & nuts

Frequently asked questions — Screws & nuts

• How do I choose between a partially threaded and a fully threaded hexagon head screw?

  The choice depends on the configuration of your mechanical assembly. For partially threaded screws compliant with ISO 4014, the unthreaded area beneath the head is suited to assemblies requiring precise centring of the parts. Conversely, fully threaded screws, meeting ISO 4017 or DIN 933, are recommended when the threaded length must be complete to ensure fastening over the entire depth of the assembled element.
• Which steel strength class should I select for my assemblies?

  The selection of the strength class, defined by ISO 898, must align with the mechanical load exerted on the assembly. Classes 8.8, 10.9 and 12.9 indicate increasing strength levels for steel fasteners. The applied load and service constraints should be evaluated to determine whether a class 8.8 is sufficient or whether higher strength, such as 10.9 or 12.9, is required to maintain the integrity of the fastening in its application environment.
• Why is it necessary to use flat washers in my fastenings?

  The use of flat washers, compliant with ISO 7089, is essential to ensure an appropriate distribution of pressure during tightening. By increasing the bearing surface beneath the screw head or beneath the type 1 hexagon nut (ISO 4032 or DIN 934), they prevent damage to contact surfaces and avoid premature loosening linked to a localised concentration of stresses on too restricted an area.
• What are the advantages of the brands distributed for screws and nuts?

  The distribution of the ACTON, SPAX, VISWOOD, REISSER, KS TOOLS, MUSTAD and SCHAEFER brands guarantees consistent technical availability of your fastening components. This selection of manufacturers meets the requirements of professionals by providing a diverse range of references that comply with the international standards mentioned. By choosing from these brands, you benefit from products whose technical characteristics, whether metric pitch screws or bolting elements, comply with the specifications required for reliable mechanical assemblies.