Metallic penetration protection usually consists of a steel strip. This is punched from a 0.7 mm thick steel strip plate. The punched-out piece of steel is attached to the safety shoes (รองเท้า เซฟตี้ which is the term in Thai) before the sole is attached. Due to the nature of the material, the inlay cannot be placed right up to the edge of the sole. Only about 85% is covered, and there is a small gap on the sides through which nails and pointed objects can penetrate.
In addition, the sole is stiffened by the steel insert, which benefits the torsion protection. The significant advantage over non-metallic inlays is that steel is much more durable. The object’s point/sharpness and shape play a less important role than with the counterpart made of textile. Another great advantage is that straight nails are often diverted and bent over on the steel sole. Especially in robust safety boots of class S5, like the one Steel inserts are popular with rubber boots.
Non-Metallic Penetration Protection For Safety Shoes
The non-metallic penetration protection consists of several layers of tightly woven textiles. KEVLAR® is often used for this, which additionally protects the sole against cuts by sharp objects. The significant advantage over its steel counterpart is its flexibility. Where a steel sole noticeably stiffens the sole, the penetration protection made of textile is barely noticeable.
In addition, it is sewn directly into the sole and thus covers the entire sole surface. The textile also does not form thermal bridges, which is particularly useful in cold environments. The disadvantage, however, is that the sole is not as durable as steel. A very pointed, thin object has little chance with a solid steel plate; it can penetrate more efficiently with a fabric.
Textile inlays are generally much more susceptible to the shape and thickness of the object. Due to their flexibility, non-metallic protective insoles are often used in shoes for frequent runners, such as the low sport safety shoes (รองเท้า safety ทรง สปอร์ต which is the term in Thai) used.