schroefdraadcode

The schroefdraadcode is a standardized shorthand notation for describing the size, pitch, and type of screw threads used in the Netherlands and other Dutch-speaking regions. It provides a quick and unambiguous reference for engineers, machinists, and procurement staff, ensuring that components can be identified, ordered, and manufactured correctly.

A typical schroefdraadcode consists of several elements written in a fixed order. The first part indicates the nominal major diameter in millimetres or a NATO designation (e.g., M6, 5/8"). This is followed by the pitch or thread angle. For metric threads the pitch is expressed in millimetres (e.g., “.7” for a 0.7 mm pitch), while for Imperial threads the designation follows the standard British system. After the pitch comes a letter that denotes the thread type, such as “N” for standard metric threads, “S” for steep angle threads, or “L” for low-profile threads. Finally, the code may include a suffix for special requirements, for example “T” for Tolerated threads or “C” for commercial tolerance.

The purpose of the code is to replace verbose descriptions in technical drawings and specification documents. When a part labelled “M6-0.7 N” is referenced, all parties automatically know that it is a 6‑mm metric screw with a 0.7‑mm pitch using a standard tolerance. This reduces miscommunication, speeds up material procurement, and helps in compatibility checks across suppliers.

Schroefdraadcodes are widely used in the Dutch aerospace, automotive, and mechanical engineering sectors. Although similar to ISO and DIN thread standards, the Dutch code remains distinct in its specific suffix letters and is often referenced in Belgian and German engineering documents. When drafting new technical drawings it is good practice to include the full schroefdraadcode on thread features, especially for custom or non‑standard threads.