8: Specifies the exact cutting diameter of 18.0 mm for the generated bore.
5D: Defines a maximum usable drilling depth ratio of 5 × Diameter, allowing a maximum drilling depth of up to 90 mm before shank interference.
U-DRILL: Identifies it as an indexable insert drill utilizing an inner (central) and outer (peripheral) insert layout rather than a solid carbide body.
Shank Standard: Typically features a 25 mm straight cylindrical Weldon shank (designated as C25-5D18 or SP18.0-5D-C25) with clamping flats to resist heavy radial and torsional force