Based on GB/T 42124.3-2025, this document explains the external draft angle, internal draft angle, DA/DB grade, and TP/TM markings for investment casting, and compiles the corresponding angles and linear values for 4–630 mm.

GB/T 42124.3-2025 has replaced GB/T 6414-2017. This article compiles the tolerance tables for DCTG4-DCTG10, recommended grades for investment casting, GCTG geometric tolerances, and RMAG E machining allowances based on the official standard text.