In order to ensure a penetration resistance according to the standard, two different types of material are used: on the one hand, it is the common steel midsole, on the other hand, for a couple of years, it has also been the textile penetration resistance.
Steel midsoles are made of flexible 0,7 mm thick steel strip stamped plates in the form of an inner sole board. They are fixed on the upper before the sole is attached. They are extremely stable and resistant against penetration of nails, mainly because the nails most often slide against the steel board and bend. Steel midsoles are slightly stiffer. der Stahlsohle abgleitet und umgebogen wird. Stahlzwischensohlen machen die Sohle geringfügig steifer.
Besides the steel midsole, there is also the alternative of a textile penetration resistance which consists of different layers, made of dense textile material, which is extremely hard for a nail to penetrate. The advantage is the better flexibility, and it is possible to produce metal-free shoes. However, for the robust use on construction sites, we recommend a steel midsole.
In general, it should be considered that in the laboratory, the shoe is tested by use of a bodkin test nail of 4,5mm diameter and a force of 1100 N. Higher force or thinner nails can increase the risk of penetration. In such cases you should take alternative preventive measures.
1100 N is about 110 kg static weight. This load can be reached already by a person of about 80kg by walking or jumping.