Spring plunger, Standard FK with pin and slot 4

Slotted screw drives are the oldest form of rotary drives for fastening screws. The Schltz is usually manufactured in a pressed or milled version. Because of its uneconomical processing method (slow, unwieldy), the slot is increasingly disappearing in favor of other drives (hexagon socket, cross slot, hexagon socket).

Grade 1.4305 is a sulphurised austenitic stainless steel of the A1 type. It is specifically intended for machining. Due to its high sulphur content of up to 0.35 per cent, this material has lower corrosion resistance than comparable stainless steels with a typical sulphur content of no more than 0.015 per cent. It is not suitable for use in non-oxidising acids and media or in chloride-containing environments (such as marine environments, etc.).

Free-cutting steels are described in ISO 683-4. A distinction is made between grades not intended for heat treatment, those intended for case hardening, and free-cutting steels intended for tempering. All steels in accordance with ISO 683-4 are easily machinable (turning, drilling, milling) due to their chip-breaking properties. Tensile strengths range from 310 to 900 MPa, depending on the heat treatment.