列出必要的信息，以确定最适合特定用途的材料。圆柱形芯通常由各种尺寸的金属制成。涂层的硬度、材料类型和表面处理因用途而异。这决定了覆盖物的物理和化学性质。一幅带有覆盖物细节的图。

Lays down the information necessary in order to determine the most suitable material for a particular purpose. The cylindrical cores are usually made of metal in a wide variety of sizes. The covering varies in hardness, type of material and surface treatment depending on use. This determines physical and chemical properties of the covering. One figure with details of the coverings.