This is an 18 mm x 1.5 HSS split die designed for cutting and restoring external ISO metric threads (M18 × 1.5). Its primary use is to form or repair M18 external threads on studs, bolts and bar stock where a hand or machine-held split die is required to provide a controlled, adjustable cut.

The die is manufactured from M2 high speed steel (HSS), hardened and ground to maintain cutting edge durability and heat resistance. The die is split to allow a small amount of radial adjustment for fine tuning thread fit and for compensating minor wear or repair work. The thread form complies with ISO metric thread geometry (ISO 68-1) and standard pitches (ISO 261 / DIN 13 / BS 3643), producing the commonly-used M18 × 1.5 metric coarse thread. The die typically has a ground face finish with an oxidised (blackened) outer surface to reduce friction and offer modest corrosion protection during storage and use.

The die is intended for use in a compatible die stock holder (hand die stock) or a suitable machine die holder, and it requires cutting lubricant for best results. Because it is HSS, it will hold form and cutting ability better than carbon steel dies when working with mild steel, stainless steels, aluminium and non-ferrous alloys; however, correct lubricant and cutting speed should be chosen for tougher materials.

Typical applications include maintenance and repair of machinery, fabrication and installation of plant equipment, automotive and agricultural repairs, and on-site thread reinstatement in engineering workshops and construction. The adjustable split design makes it particularly useful where a close fit is required or where threads need slight resizing during refurbishment.

Key benefits are the wear resistance and temperature tolerance of M2 HSS for extended life, the adjustability of the split design to control fit and compensate for wear, and compatibility with standard M18 fasteners and die stocks. Duchy Fasteners holds a wide stock range of HSS split dies and die sets in metric sizes including M18 × 1.5, available as single dies or in multi-size packs, along with matching die holders and accessories.