Precision Casting Tolerance Standards Guide

The dimensional accuracy of castings is one of their key quality indicators, and casting dimensional tolerance standards serve as the objective basis for assessing this accuracy. Auderson Metal strictly adheres to the national standard GB/T6414-2017.

For investment castings, the corresponding tolerance grade is selected based on the maximum nominal dimension, as follows:

1：When the maximum nominal dimension is ≤ 100, select grades DCTG4 through DCTG6.

2：100 < Maximum Nominal Dimension ≤ 400: Select Grade DCTG4 to DCTG8.

3：When the maximum nominal size exceeds 400, select grades DCTG4 through DCTG9.

Casting Dimensional Tolerance (DCTG)

Nominal Size		Casting Dimensional Tolerance Grade (DCTG) and Corresponding Linear Dimension Tolerance Values
Above	Up to	DCTG1	DCTG2	DCTG3	DCTG4	DCTG5	DCTG6	DCTG7	DCTG8	DCTG9
–	10	0.09	0.13	0.18	0.26	0.36	0.52	0.74	1	1.5
10	16	0.1	0.14	0.2	0.28	0.38	0.54	0.78	1.1	1.6
16	25	0.11	0.15	0.22	0.3	0.42	0.58	0.82	1.2	1.7
25	40	0.12	0.17	0.24	0.32	0.46	0.64	0.9	1.3	1.8
40	63	0.13	0.18	0.26	0.36	0.5	0.7	1	1.4	2
63	100	0.14	0.2	0.28	0.4	0.56	0.78	1.1	1.6	2.2
100	160	0.15	0.22	0.3	0.44	0.62	0.88	1.2	1.8	2.5
160	250	–	0.24	0.34	0.5	0.7	1	1.4	2	2.8
250	400	–	–	0.4	0.56	0.78	1.1	1.6	2.2	3.2
400	630	–	–	–	0.64	0.9	1.2	1.8	2.6	3.6
630	1000	–	–	–	0.72	1	1.4	2	2.8	4

Casting Straightness Tolerance

Nominal Size		Casting Geometrical Tolerance Grade (GCTG) and Corresponding Straightness Tolerances
Above	Up to	DCTG2	DCTG3	DCTG4	DCTG5	DCTG6	DCTG7	DCTG8
–	10	0.08	0.12	0.18	0.27	0.4	0.6	0.9
10	30	0.12	0.18	0.27	0.4	0.6	0.9	1.4
30	100	0.18	0.27	0.4	0.6	0.9	1.4	2
100	300	0.27	0.4	0.6	0.9	1.4	2	3
300	1000	0.4	0.6	0.9	1.4	2	3	4.5
1000	3000	–	–	–	3	2	6	9
3000	6000	–	–	–	6	8	12	18
6000	10000	–	–	–	12	16	24	36

Casting Flatness Tolerance

Nominal Size		Casting Geometrical Tolerance Grade (DCTG) and Corresponding Flatness Tolerances
Above	Up to	DCTG2	DCTG3	DCTG4	DCTG5	DCTG6	DCTG7	DCTG8
–	10	0.12	0.18	0.27	0.4	0.6	0.9	1.4
10	30	0.18	0.27	0.4	0.6	0.9	1.4	2
30	100	0.27	0.4	0.6	0.9	1.4	2	3
100	300	0.4	0.6	0.9	1.4	2	3	4.5
300	1000	0.6	0.9	1.4	2	3	4.5	7
1000	3000	–	–	–	4	6	9	14
3000	6000	–	–	–	8	12	18	28
6000	10000	–	–	–	16	24	36	56

Casting Tolerances for Roundness, Parallelism, Perpendicularity, and Symmetry

Nominal Size		Casting Geometrical Tolerance Grade (DCTG) and Corresponding Tolerances
Above	Up to	DCTG2	DCTG3	DCTG4	DCTG5	DCTG6	DCTG7	DCTG8
–	10	0.18	0.27	0.4	0.6	0.9	1.4	2
10	30	0.27	0.4	0.6	0.9	1.4	2	3
30	100	0.4	0.6	0.9	1.4	2	3	4.5
100	300	0.6	0.9	1.4	2	3	4.5	7
300	1000	0.9	1.4	2	3	4.5	7	10
1000	3000	–	–	–	6	9	14	20
3000	6000	–	–	–	12	18	28	40
6000	10000	–	–	–	24	36	56	80

Casting Coaxiality Tolerance

Nominal Size		Casting Geometrical Tolerance Grade (DCTG) and Corresponding Coaxiality Tolerances
Above	Up to	DCTG2	DCTG3	DCTG4	DCTG5	DCTG6	DCTG7	DCTG8
–	10	0.27	0.4	0.6	0.9	1.4	2	3
10	30	0.4	0.6	0.9	1.4	2	3	4.5
30	100	0.6	0.9	1.4	2	3	4.5	7
100	300	0.9	1.4	2	3	4.5	7	10
300	1000	1.4	2	3	4.5	7	10	15
1000	3000	–	–	–	9	14	20	30
3000	6000	–	–	–	18	28	40	60
6000	10000	–	–	–	36	56	80	120