DIY Knowledge

Screwdriving conditions


Tipo de unión atornillada

Vissage (Types de vissages)

The torque which can be effectively transferred by the screwdriver to the screw head depends on the prevailing screwdriving conditions. A distinction is made between hard and soft screwdriving conditions.

Hard screwdriving conditions (extreme case): a short metrical steel screw is screwed into a prepared thread until the hexagonal head comes to rest on the steel surface and tightened.

Soft screwdriving conditions (extreme case): plasterboard is screwed onto spruce wood using a self-drilling screw with trumpet head.

There is a virtually infinite number of possible variations between extremely soft and hard conditions. With equal settings of the screwdriver, the torque applied to the screw is the highest under hard screwdriving conditions and the lowest possible under soft screwdriving conditions.

The hardness of the screwdriving conditions is determined by:

- the material of the nut thread, or the nut rest

- the material of the screwhead rest

- the condition of the thread

- the material of the screw barrel

- the length of the screw barrel

- the diameter of the screw barrel

- the thread pitch

- the lubrication of the screw

- the head shape of the screw

- the shape and material of washers