The DIN EN 22568 HSS-G fully ground circular dies for UNF threads are designed for producing external American Unified National Fine threads according to ANSI B1.1 on rods, pins, studs, special screws, mechanical components and parts requiring thread repair. UNF threads, with their finer pitch compared with UNC threads, are suitable when more accurate adjustment, stronger threaded engagement, better resistance to loosening and more controlled tightening are required, especially on mechanical parts, automotive components, equipment, industrial spare parts and machinery using inch-based standards.

The fully ground HSS-G high-speed steel construction provides accurate cutting geometry, stable thread profile and consistent thread quality. The ground cutting edges allow smoother machining compared with non-ground tools, improving die feed, thread profile cleanliness and repeatability. The 60° profile, 2A tolerance and closed pre-slotted Form B geometry allow controlled external UNF threads to be produced in accordance with American standard fits. The closed Form B design provides stable guidance when starting the thread on the workpiece, while the pre-slotted construction helps distribute cutting forces and supports uniform thread formation.

These dies are suitable for materials with tensile strength up to approximately 800 N/mm², including structural steels, unalloyed steels, free-cutting steels, mild steels and general metallic materials compatible with HSS-G cutting tools. Compared with UNC dies, UNF versions work with a finer pitch and require greater attention to starting alignment, coaxial guidance and lubrication, because the thread profile is closer and may be more affected by incorrect workpiece diameter, misalignment or chip accumulation.

To obtain accurate threads, the external workpiece diameter must be prepared correctly, a suitable starting chamfer must be made, the die must be kept coaxial and perpendicular to the component axis, and appropriate cutting lubricant must be used. Incorrect workpiece diameter, misaligned starting or insufficient lubrication can cause incomplete threads, torn thread profiles, increased cutting effort, premature die wear and difficult feeding. During machining, progressive cutting and periodic chip breaking are recommended, especially on larger diameters and tougher materials. These dies are suitable for mechanical workshops, maintenance technicians, toolrooms, production departments, automotive applications, industrial repair and machining of components with UNF standards, where precision, reliability and compatibility with American fine threads are required.