Are accuracy grade and preload the same thing?

No. Accuracy grade sets dimensional tolerance and running parallelism (geometry); preload sets radial clearance and stiffness (performance). They are chosen independently.

How do rail length and accuracy grade trade off?

Pick the rail-length band from your stroke, then read Table 2.5.1 to see the parallelism it allows. For a 1250 mm stroke: N 22 µm, H 16 µm, P 10 µm. If the machine needs better than 10 µm, P or above is mandatory.

Which accuracy can I get as separate blocks?

Separate blocks top out at P. For SP or UP you need a factory-matched set, which gives higher combination accuracy but blocks cannot be swapped individually.

Linear Guide Accuracy Grades N/H/P/SP/UP and Running Parallelism Tables

How to choose linear guide accuracy: five grades from Standard N to Ultra Precision UP, running parallelism in16 rail-length bands (0~125 to 3500~4000 µm), plus dimensional tolerances and pairwise differences for height M and width W2.

1. The five accuracy grades

TR / SR linear guides come in five accuracy grades. Higher grades mean tighter tolerances and better running parallelism, at a higher cost.

Grade	Name	Typical use
N	Standard	General automation, conveying
H	High	General machine tools, positioning
P	Precision	CNC lathe, machining centre
SP	Super precision	Grinding, precision machining
UP	Ultra precision	Semiconductor, metrology (matched sets only)

Ultra precision UP is only available as a factory-matched set; separate-type blocks top out at P.

2. Table 2.5.1 Running parallelism by rail length

This is the most-asked table: at grade N, a 1000 mm rail and a 100 mm rail differ enormously. Longer rails lose parallelism, so long strokes need a higher grade.

Rail length (mm)	N	H	P	SP	UP
0~125	5	3	2	1.5	1
125~200	5	3.5	2	1.5	1
200~250	6	4	2.5	1.5	1
250~315	7	4.5	3	1.5	1
315~400	8	5	3.5	2	1.5
400~500	9	6	4.5	2.5	1.5
500~630	16	11	6	2.5	1.5
630~800	18	12	7	3	2
800~1000	20	14	8	4	2
1000~1250	22	16	10	5	2.5
1250~1600	25	18	11	6	3
1600~2000	28	20	13	7	3.5
2000~2500	30	22	15	8	4
2500~3000	32	24	16	9	4.5
3000~3500	33	25	17	11	5
3500~4000	34	26	18	12	6

Values in µm. The ∆C / ∆D parallelism in Table 2.5.2 works together with this table.

3. Table 2.5.2 Dimensional tolerances and pairwise differences

Pairwise difference is the mismatch between two rails used as a pair; it drives twin-rail parallelism and matters more than the single-part tolerance.

Size group	Grade	Item	Value (mm)	Item	Value (mm)	Item	Value (mm)
TR / SR 15, 20	N	Height M tolerance	±0.1	Height M pairwise diff.	0.02	Width W2 pairwise diff.	0.02
	H	Height M tolerance	±0.03	Height M pairwise diff.	0.01	Width W2 pairwise diff.	0.01
	P	Height M tolerance	0 / −0.03	Height M pairwise diff.	0.006	Width W2 pairwise diff.	0.006
	SP	Height M tolerance	0 / −0.015	Height M pairwise diff.	0.004	Width W2 pairwise diff.	0.004
	UP	Height M tolerance	0 / −0.008	Height M pairwise diff.	0.003	Width W2 pairwise diff.	0.003
TR / SR 25, 30, 35	N	Height M tolerance	±0.1	Height M pairwise diff.	0.02	Width W2 pairwise diff.	0.03
	H	Height M tolerance	±0.04	Height M pairwise diff.	0.015	Width W2 pairwise diff.	0.015
	P	Height M tolerance	0 / −0.04	Height M pairwise diff.	0.007	Width W2 pairwise diff.	0.007
	SP	Height M tolerance	0 / −0.02	Height M pairwise diff.	0.005	Width W2 pairwise diff.	0.005
	UP	Height M tolerance	0 / −0.01	Height M pairwise diff.	0.003	Width W2 pairwise diff.	0.003
TR / SR 45, 55	N	Height M tolerance	±0.1	Height M pairwise diff.	0.03	Width W2 pairwise diff.	0.03
	H	Height M tolerance	±0.05	Height M pairwise diff.	0.015	Width W2 pairwise diff.	0.02
	P	Height M tolerance	0 / −0.05	Height M pairwise diff.	0.007	Width W2 pairwise diff.	0.01
	SP	Height M tolerance	0 / −0.03	Height M pairwise diff.	0.005	Width W2 pairwise diff.	0.007
	UP	Height M tolerance	0 / −0.02	Height M pairwise diff.	0.003	Width W2 pairwise diff.	0.005
TR 65	N	Height M tolerance	±0.1	Height M pairwise diff.	0.03	Width W2 pairwise diff.	0.03
	H	Height M tolerance	±0.07	Height M pairwise diff.	0.02	Width W2 pairwise diff.	0.025
	P	Height M tolerance	0 / −0.07	Height M pairwise diff.	0.01	Width W2 pairwise diff.	0.015
	SP	Height M tolerance	0 / −0.05	Height M pairwise diff.	0.007	Width W2 pairwise diff.	0.01
	UP	Height M tolerance	0 / −0.03	Height M pairwise diff.	0.005	Width W2 pairwise diff.	0.007

FAQ

Are accuracy grade and preload the same thing?: No. Accuracy grade sets dimensional tolerance and running parallelism (geometry); preload sets radial clearance and stiffness (performance). They are chosen independently.
How do rail length and accuracy grade trade off?: Pick the rail-length band from your stroke, then read Table 2.5.1 to see the parallelism it allows. For a 1250 mm stroke: N 22 µm, H 16 µm, P 10 µm. If the machine needs better than 10 µm, P or above is mandatory.
Which accuracy can I get as separate blocks?: Separate blocks top out at P. For SP or UP you need a factory-matched set, which gives higher combination accuracy but blocks cannot be swapped individually.

Selection Tree Shaft-end machining

All tables from the MOSIONX 2026 general catalogue, chapter A pages A81–A82 (accuracy grades).

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Linear Guide Accuracy Grades N/H/P/SP/UP and Running Parallelism Tables

On this page

1. The five accuracy grades

2. Table 2.5.1 Running parallelism by rail length

3. Table 2.5.2 Dimensional tolerances and pairwise differences

FAQ

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