S: Identifies the fundamental physical shape as a Square (90° included angles). The square geometry provides a total of 4 usable cutting edges with exceptional core strength.
P: Specifies a 11° Normal Clearance Angle (Positive insert layout). This built-in relief angle reduces friction and cutting forces, allowing it to plunge cleanly into materials without causing excessive spindle drag.
K: Dictates the universal Tolerance Class (Class K). This standard milling tolerance ensures highly repeatable limits for the thickness (±0.025 mm) and indexing precision across the entire pocket layout of a multi-insert cutter head.
N: Confirms the physical clamping structural style. It indicates a solid top and bottom face without a central fixing hole, meaning the insert relies entirely on an upper wedge-lock or a top-clamp mechanism inside the milling body pocket.
15: Details the nominal metric Inscribed Circle (IC) size, measuring exactly 15.875 mm (5/8 inch).
04: Defines the standard physical Insert Thickness, which is 4.76 mm.