What is the difference between a linear guide and a ball way?

A linear guide has four-point ball contact with equal load in all four directions and takes moments; a ball way has two-point contact, carries radial load only and cannot take moments. If the application has cantilever or tilting moments, a linear guide is mandatory.

Is the static safety factor the same as life?

No. fS checks against crushing under peak load; life checks against wear. Compute both: fS from the maximum load and life from the average load — both must pass.

Should I pick preload Z1 or Z2?

Match the accuracy and stiffness demand. Pick Z1 when you need low friction without high accuracy; pick Z2 for high stiffness under shock (CNC lathe, machining centre) and also for light-load high-accuracy stages such as precision XY tables and inspection equipment.

What about using multiple blocks in tandem?

Always apply the contact factor fc for tandem blocks (2 → 0.81, 3 → 0.72, 4 → 0.66, 5 → 0.61, 6+ → 0.6) or you will overestimate capacity. Use the tandem-column K values as well.

Is there a requirement for shoulder height?

Yes. An over-large chamfer hurts accuracy and an over-tall shoulder fouls the block. Follow table 1.11.4 — e.g. TR/SR30 needs r1 = 1.0, r2 = 1, E1 = 5, E2 = 5 and running clearance H1 = 7 mm.

Linear Guide Selection Guide: Load, Life, Accuracy and Preload

How to select a linear guide: the five MOSIONX series (TR/SRH, SRS, SRC, TM-N, TM-W) with full tables for static safety factor, contact and load factors, friction, moment equivalent coefficients, preload classes, tightening torque and shoulder dimensions.

The linear guide is the primary moving element on machine tools and automation cells. The tables below reorganise the engineering data from catalogue chapter A into directly usable form: the coefficients used in life calculation, accuracy and preload classes, mounting torque and shoulder dimensions.

1. Guide series and sizes 2. Five advantages of linear guides 3. Life calculation and the four coefficients Table 1.3.2 Contact coefficient fc (by block count)Table 1.3.3 Load factor fW (by speed)4. Static safety factor fS 5. Friction comparison: why linear guides 6. Moment equivalent coefficients Ky / Kz / Kx 7. Worked example: TRH30FE reaching 59,800 hours 8. Radial clearance and preload ZF–Z0 / Z1 / Z2 9. Mounting torque and shoulder dimensions 10. Lubrication FAQ

1. Guide series and sizes

MOSIONX linear guides fall into five series by load capacity; within each series the suffix encodes accuracy and preload combination.

Series	Description	Sizes	Rolling element	Typical use
TR	TR / SRH heavy-duty series	15 / 20 / 25 / 30 / 35 / 45 / 55 / 65	Four-row ball	General heavy duty, equal load in all four directions, highest stiffness; the default for machine tools and heavy conveying
TR	TR / SRS medium-duty series	15 / 20 / 25 / 30 / 35 / 45	Four-row ball	Medium duty and best cost-performance, with broad size coverage
TR	TR / SRC low-profile series	25	Four-row ball	For constrained mounting space and shorter strokes
TM-N	TM-N miniature series	03 / 05 / 07 / 09 / 12 / 15	Miniature block	Semiconductor, inspection equipment, short-stroke high-speed mechanisms
TM-W	TM-W wide miniature series	07 / 09 / 12 / 15	Miniature block	Wide tables needing higher stiffness while keeping a small envelope

Suffix meaning: V flange, S wide block, E light preload, N zero clearance, L low-mount.

2. Five advantages of linear guides

High positioning accuracy：Rolling instead of sliding friction generates very little heat, so positioning and travel accuracy hold over long periods with minimal wear.
High stiffness：Four-direction equal-load design resists load in every direction and self-centres, tolerating larger mounting error.
Easy maintenance：Guides are interchangeable: replace a worn unit and accuracy returns, instead of scraping and hand-scraping the way as with sliding systems.
High speed capability：Point-contact rolling has a very low coefficient and generates little heat, so the drive power stays low at high speed.
Zero clearance and high mechanical efficiency：The ball-to-raceway contact point stays constant, differential sliding stays small, giving smooth motion and high mechanical efficiency.

3. Life calculation and the four coefficients

For travel-based rated life, four correction coefficients apply:

L = (fh · ft · fc / fW)³ × (C / PC)³ [km]

Coefficient	Meaning	Value
<	b	>	f	h	<	/	b	>	h	a	r	d	n	e	s	s		f	a	c	t	o	r
<	b	>	f	t	<	/	b	>	t	e	m	p	e	r	a	t	u	r	e		f	a	c	t	o	r
<	b	>	f	c	<	/	b	>	c	o	n	t	a	c	t		f	a	c	t	o	r
<	b	>	f	W	<	/	b	>	l	o	a	d		f	a	c	t	o	r

Table 1.3.2 Contact coefficient fc (by block count)

Blocks in tandem	Contact factor fc
1	1
2	0.81
3	0.72
4	0.66
5	0.61
6 or more	0.6

Table 1.3.3 Load factor fW (by speed)

Level	Speed V	fW
Micro	V ≤ 0.25 m/s	1 – 1.2
Low	0.25 < V ≤ 1 m/s	1.2 – 1.5
Medium	1 < V ≤ 2 m/s	1.5 – 2
High	V > 2 m/s	2 – 3.5

4. Static safety factor fS

Vibration, shock and start/stop inertia act on the system at rest and in motion, so a static safety factor check is mandatory.

fS = C0 / P or fS = C0 / M0

C0 is the basic static load rating (kg) and M0 the allowable static moment (kg·mm). For very large radial, reverse-radial or transverse loads, C0 ≥ fS · fh · ft · fc · P applies.

Machine	Load condition	fS lower limit
General industry machinery	No vibration / shock	1.0 – 1.3
General industry machinery	With vibration / shock	2.0 – 3.0
Machine tools	No vibration / shock	1.0 – 1.5
Machine tools	With vibration / shock	2.5 – 7.0

5. Friction comparison: why linear guides

Linear guide friction is about 1/20 to 1/40 of a sliding way, with a coefficient around 0.002–0.003.

System type	Friction coefficient μ
Linear bushing	0.0006 – 0.0012
Cross-roller way	0.0010 – 0.0025
Linear guide / ball spline	0.002 – 0.003
Roller	0.0050 – 0.010

6. Moment equivalent coefficients Ky / Kz / Kx

When moment load applies, convert the moments in all three directions into equivalent load. Kx is rolling, Ky is pitching, Kz is yawing, in mm⁻¹.

Model	Ky (mm⁻¹)	Kz (mm⁻¹)	Kx (mm⁻¹)
TR / SRH15VN	1.48×10⁻¹	3.11×10⁻²	1.34×10⁻¹
TR / SRH20VN	1.11×10⁻¹	2.35×10⁻²	9.90×10⁻²
TR / SRH20VE	8.00×10⁻²	1.78×10⁻²	9.90×10⁻²
TR / SRH25VN	1.04×10⁻¹	2.17×10⁻²	8.62×10⁻²
TR / SRH25VE	7.35×10⁻²	1.60×10⁻²	8.62×10⁻²
TR / SRH30VN	6.52×10⁻²	1.34×10⁻²	7.69×10⁻²
TR / SRH30VE	6.12×10⁻²	1.33×10⁻²	7.15×10⁻²
TR / SRH35VN	6.95×10⁻²	1.43×10⁻²	6.29×10⁻²
TR / SRH35VE	5.25×10⁻²	1.15×10⁻²	5.85×10⁻²
TR / SRH45VL	5.80×10⁻²	1.24×10⁻²	4.38×10⁻²
TR / SRH45VE	4.59×10⁻²	1.00×10⁻²	4.38×10⁻²
TRH55VL	5.25×10⁻²	1.07×10⁻²	3.78×10⁻²
TRH55VE	4.08×10⁻²	8.69×10⁻³	3.78×10⁻²
TRH65VL	4.52×10⁻²	8.76×10⁻³	3.24×10⁻²
TRH65VE	3.27×10⁻²	6.77×10⁻³	3.24×10⁻²

TR / SRS series

Model	Ky (mm⁻¹)	Kz (mm⁻¹)	Kx (mm⁻¹)
TR / SRS15VS	2.29×10⁻¹	4.39×10⁻²	1.34×10⁻¹
TR / SRS15VN	1.48×10⁻¹	3.11×10⁻²	1.34×10⁻¹
TR / SRS20VS	2.00×10⁻¹	3.58×10⁻²	9.90×10⁻²
TR / SRS20VN	1.25×10⁻¹	2.60×10⁻²	9.90×10⁻²
TR / SRS25VS	1.60×10⁻¹	3.07×10⁻²	8.62×10⁻²
TR / SRS25VN	1.04×10⁻¹	2.17×10⁻²	8.62×10⁻²
TR / SRS30VS	1.47×10⁻¹	2.57×10⁻²	7.15×10⁻²
TR / SRS30VN	8.65×10⁻²	1.82×10⁻²	7.15×10⁻²
TR / SRS35VN	7.87×10⁻²	1.61×10⁻²	5.85×10⁻²
TR / SRS35VE	5.25×10⁻²	1.15×10⁻²	5.85×10⁻²
TR / SRS45VN	6.89×10⁻²	1.39×10⁻²	4.38×10⁻²

TM-N / TM-W miniature series

Model	Ky (mm⁻¹)	Kz (mm⁻¹)	Kx (mm⁻¹)
TM03NN	9.26×10⁻¹	13.37×10⁻²	6.22×10⁻¹
TM05NN	7.00×10⁻¹	11.67×10⁻²	3.82×10⁻¹
TM07NN	4.42×10⁻¹	7.24×10⁻²	2.68×10⁻¹
TM09NN	3.52×10⁻¹	5.39×10⁻²	2.20×10⁻¹
TM12NN	2.84×10⁻¹	4.80×10⁻²	1.53×10⁻¹
TM15NN	2.60×10⁻¹	4.10×10⁻²	1.24×10⁻¹
TM07WN	2.89×10⁻¹	5.60×10⁻²	13.1×10⁻²
TM09WN	2.19×10⁻¹	4.45×10⁻²	10.3×10⁻²
TM12WN	2.02×10⁻¹	3.83×10⁻²	7.97×10⁻²
TM15WN	1.59×10⁻¹	2.95×10⁻²	4.61×10⁻²

K differs between a single block and two blocks in tandem; the values above are for one block. For tandem pairs see catalogue tables 1.6.x.

7. Worked example: TRH30FE reaching 59,800 hours

Given: block TRH30FE, C0 = 9004 kg, C = 4791 kg, working load PC = 266.5 kg. fc = 1 (single block), fW = 1.5 (speed 0.25–1 m/s), ft = 1 (below 100 °C), fh = 1 (HRC 58–62).

Item	Calculation	Result
Rated life (travel)	(fh·ft·fc/fW)³ × (C/PC)³	86,112 km
Rated life (revolutions)	86,112×1000 ÷ 6 m per cycle	14,352,000 cycles
Rated life (hours)	14,352,000 ÷ 4 cycles/min	59,800 hours

Basis: 3000 mm stroke, 6 m per round trip, 4 round trips per minute. Check the result against the required life with a margin.

8. Radial clearance and preload ZF–Z0 / Z1 / Z2

Preload directly sets stiffness and life: once preloaded the block carries internal load, so the preload must be included in the life calculation. With four-direction equal-load design, the preload benefit holds until the external load reaches about 2.8× the preload.

Class	Type	Working condition	Typical machines
ZF – Z0	Micro clearance, no preload	Constant load direction, low vibration, twin-axis parallel layouts	Welding, packaging, general XY axes
Z1	Zero clearance, light preload	Low accuracy but low friction; cantilevered or moment-loaded, single axis	Welding, fusing, tool changer, feeders
Z2	Zero clearance, medium preload	Light load with high accuracy; high stiffness with shock; heavy cutting	CNC lathe, machining centre, grinding wheel feed, mill, boring machine

9. Mounting torque and shoulder dimensions

Table 1.11.3 Hex-socket bolt tightening torque (N·cm)

Bolt	Steel	Cast iron	Aluminium
M2	57	39.2	29.4
M2.3	78.4	53.9	39.2
M2.6	118	78.4	58.8
M3	186	127	98.0
M4	392	274	206
M5	882	588	441
M6	1370	921	686
M8	3040	2010	1470
M10	6760	4510	3330
M12	11800	7840	5880
M14	15700	10500	7840
M16	19600	13100	9800
M20	38200	25500	19100
M22	51900	34800	26000
M24	65700	44100	32800
M30	130000	87200	65200

Tighten from the centre outwards so the rail seats flat against the mounting face, then re-torque with a wrench to the specified value.

Table 1.11.4 Shoulder height and chamfer radius (mm)

Size	Mount chamfer r1	Mount chamfer r2	Rail shoulder E1	Block shoulder E2	Running clearance H1
TR / SR15	0.5	0.5	3	4	3.2
TR / SR20	0.5	0.5	3.5	5	4.6
TR / SR25	1.0	0.9	5	5	5.8
TR / SR30	1.0	1	5	5	7
TR / SR35	1.0	1	6	6	7.5
TR / SR45	1.0	1	8	8	8.9
TR55	1.5	1.5	10	10	13
TR65	1.5	1.5	8	10	14.3

10. Lubrication

Even with seals, lubricant seeps out during running, so it must be topped up on a schedule. The catalogue suggests replenishing grease every 100 km.

Type	Spec / product
Grease	Lithium-complex (JIS No.2); urea-complex (JIS No.2); 4FB grease (MOSIONX)
Oil	ISO VG32–68 slideway or turbine oil

FAQ

What is the difference between a linear guide and a ball way?: A linear guide has four-point ball contact with equal load in all four directions and takes moments; a ball way has two-point contact, carries radial load only and cannot take moments. If the application has cantilever or tilting moments, a linear guide is mandatory.
Is the static safety factor the same as life?: No. fS checks against crushing under peak load; life checks against wear. Compute both: fS from the maximum load and life from the average load — both must pass.
Should I pick preload Z1 or Z2?: Match the accuracy and stiffness demand. Pick Z1 when you need low friction without high accuracy; pick Z2 for high stiffness under shock (CNC lathe, machining centre) and also for light-load high-accuracy stages such as precision XY tables and inspection equipment.
What about using multiple blocks in tandem?: Always apply the contact factor fc for tandem blocks (2 → 0.81, 3 → 0.72, 4 → 0.66, 5 → 0.61, 6+ → 0.6) or you will overestimate capacity. Use the tandem-column K values as well.
Is there a requirement for shoulder height?: Yes. An over-large chamfer hurts accuracy and an over-tall shoulder fouls the block. Follow table 1.11.4 — e.g. TR/SR30 needs r1 = 1.0, r2 = 1, E1 = 5, E2 = 5 and running clearance H1 = 7 mm.

Ball Screw Selection Selection Tree Screw Life Calculation Mounting Torque & Pre-stretch Support Unit Cards Request a Quote

All coefficient and dimension tables come from the MOSIONX 2026 general catalogue, chapter A (linear guides, A01–A100); the worked example is the catalogue example on page A10.

Request a Quote Open Selector →Selection Tree

Model Index

121 models in total (TR/SR 85 + TM miniature 36). Click any model for its spec page.

Group	Description	Models	Model list
TRH-V	TRH-V	15	TRH15VN TRH20VE TRH20VN TRH25VE TRH25VN TRH30VE TRH30VN TRH35VE TRH35VN TRH45VE TRH45VL TRH55VE TRH55VL TRH65VE TRH65VL
TRH-F	TRH-F	15	TRH15FN TRH20FE TRH20FN TRH25FE TRH25FN TRH30FE TRH30FN TRH35FE TRH35FN TRH45FE TRH45FL TRH55FE TRH55FL TRH65FE TRH65FL
TRS-V	TRS-V	11	TRS15VN TRS15VS TRS20VN TRS20VS TRS25VN TRS25VS TRS30VN TRS30VS TRS35VE TRS35VN TRS45VN
TRS-F	TRS-F	6	TRS15FN TRS15FS TRS20FN TRS20FS TRC25VE TRS25FN
SRH-V	SRH-V	11	SRH15VN SRH20VE SRH20VN SRH25VE SRH25VN SRH30VE SRH30VN SRH35VE SRH35VN SRH45VE SRH45VL
SRH-F	SRH-F	11	SRH15FN SRH20FE SRH20FN SRH25FE SRH25FN SRH30FE SRH30FN SRH35FE SRH35FN SRH45FE SRH45FL
SRS-V	SRS-V	11	SRS15VN SRS15VS SRS20VN SRS20VS SRS25VN SRS25VS SRS30VN SRS30VS SRS35VE SRS35VN SRS45VN
SRS-F	SRS-F	5	SRS15FN SRS15FS SRS20FN SRS20FS SRS25FN
TM stainless, standard	TM stainless, standard	12	TM03NLS TM03NNS TM05NLS TM05NNS TM07NLS TM07NNS TM09NLS TM09NNS TM12NLS TM12NNS TM15NLS TM15NNS
TM stainless, wide	TM stainless, wide	8	TM07WLS TM07WNS TM09WLS TM09WNS TM12WLS TM12WNS TM15WLS TM15WNS
TM carbon steel, standard	TM carbon steel, standard	8	TM07NLA TM07NNA TM09NLA TM09NNA TM12NLA TM12NNA TM15NLA TM15NNA
TM carbon steel, wide	TM carbon steel, wide	8	TM07WLA TM07WNA TM09WLA TM09WNA TM12WLA TM12WNA TM15WLA TM15WNA

Coefficient	Meaning	Value
<	b	>	f	h	<	/	b	>	h	a	r	d	n	e	s	s		f	a	c	t	o	r
<	b	>	f	t	<	/	b	>	t	e	m	p	e	r	a	t	u	r	e		f	a	c	t	o	r
<	b	>	f	c	<	/	b	>	c	o	n	t	a	c	t		f	a	c	t	o	r
<	b	>	f	W	<	/	b	>	l	o	a	d		f	a	c	t	o	r

Coefficient	Meaning	Value
<	b	>	f	h	<	/	b	>	h	a	r	d	n	e	s	s		f	a	c	t	o	r
<	b	>	f	t	<	/	b	>	t	e	m	p	e	r	a	t	u	r	e		f	a	c	t	o	r
<	b	>	f	c	<	/	b	>	c	o	n	t	a	c	t		f	a	c	t	o	r
<	b	>	f	W	<	/	b	>	l	o	a	d		f	a	c	t	o	r