Thread fit / thread functionality

Thread fit (Gewindegängigkeit) describes a thread's ability to still function correctly after a coating has been applied, i.e. to be screwed in and out without binding. Since every coating adds a layer thickness to the component, this must either be tolerated or specifically accounted for on threaded parts so that screws, nuts or tapped holes do not jam. This is especially relevant in the optical industry and wherever tight tolerances are required. Suitable coating processes with good thread fit include, depending on the base material, anodising (aluminium), electroless nickel (various materials), passivation (aluminium, stainless steel) or black oxidising (stainless steel, brass).