Description

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DLY precision linear bearings use recirculating balls to provide low-friction linear movement along a matching hardened round shaft. Available configurations include standard LM and LME cylindrical bearings, LM…LUU and LME…LUU long bearings, long flange bearings and ST-series linear-motion bearings.

Shaft diameters from 3 mm to 150 mm are covered across the available series. Closed cylindrical, long cylindrical, round-flange, square-flange and oval-flange structures allow the bearing to be selected according to the shaft diameter, housing design, mounting interface, available length and required dynamic and static load ratings.

Each precision linear bearing must be matched with a suitable precision linear shaft. Final operating clearance, service life and motion quality depend on the bearing model, shaft diameter and tolerance, housing fit, lubrication, mounting alignment, load direction and contamination control.

Precision Linear Bearing Series

Series	Structure	Shaft Range	Available Models	Selection Focus
LM…UU	Standard closed cylindrical	3–150 mm	LM3UU–LM150UU	Broad metric size range and compact housing installation
LME…UU	Standard closed cylindrical	4–80 mm	LME4UU–LME80UU	European dimensional series and matching housing interface
LM…LUU	Long closed cylindrical	3–60 mm	LM3LUU–LM60LUU	Longer bearing body and additional ball-circulation contact
LME…LUU	Long closed cylindrical	8–60 mm	LME8LUU–LME60LUU	European long-series outside dimensions
LMF…LUU	Long round flange	6–60 mm	LMF6LUU–LMF60LUU	Round flange mounting pattern
LMK…LUU	Long square flange	6–60 mm	LMK6LUU–LMK60LUU	Square flange and four-point mounting
LMH…LUU	Long oval flange	6–30 mm	LMH6LUU–LMH30LUU	Narrow flange width and two-side mounting
LMEF/LMEK…LUU	European long round or square flange	8–60 mm	LMEF8LUU–LMEF60LUU; LMEK8LUU–LMEK60LUU	European outside diameter and flange interface
ST…UU	Closed cylindrical, high-temperature series	8–100 mm	ST8UU–ST100UU	Temperature, lubricant, seals and materials require confirmation
ST…UUB	Closed cylindrical, higher-load high-temperature series	20–100 mm	ST20UUB–ST100UUB	Higher listed load ratings with a shorter maximum travel route

Series compatibility: LM and LME bearings with the same shaft diameter do not necessarily have the same outside diameter or overall length. For example, LM12UU has a 21 mm outside diameter, while LME12UU has a 22 mm outside diameter. Existing housings must be checked before replacement.

Standard LM and LME Bearing Dimensions

The table below lists commonly selected standard LM and LME closed cylindrical bearings. C is the basic dynamic load rating and C₀ is the basic static load rating. Both are rated values rather than the maximum permissible load of the completed machine.

Model	Shaft dr (mm)	Outer D (mm)	Length L (mm)	C (N)	C₀ (N)	Weight (g)
LM8UU	8	15	24	274	392	16
LME8UU	8	16	25	265	402	20
LM12UU	12	21	30	510	784	31.5
LME12UU	12	22	32	510	784	41
LM16UU	16	28	37	774	1180	69
LME16UU	16	26	36	578	892	57
LM20UU	20	32	42	882	1370	87
LME20UU	20	32	45	862	1370	91
LM25UU	25	40	59	980	1570	220
LME25UU	25	40	58	980	1570	215
LM30UU	30	45	64	1570	2740	250
LME30UU	30	47	68	1570	2740	325
LM40UU	40	60	80	2160	4020	585
LME40UU	40	62	80	2160	4020	705
LM50UU	50	80	100	3820	7940	1580
LME50UU	50	75	100	3820	7940	1130
LM60UU	60	90	110	4700	10000	2000
LME60UU	60	90	125	4700	9800	2050

Long LM and LME Linear Bearings

LM…LUU and LME…LUU bearings use a longer closed cylindrical body than the corresponding standard series. The longer construction provides additional ball-circulation contact and higher listed load ratings for many equivalent shaft sizes, but it also requires more axial housing space.

Model	Shaft dr (mm)	Outer D (mm)	Length L (mm)	C (N)	C₀ (N)
LM8LUU	8	15	45	413	784
LME8LUU	8	16	45	431	784
LM12LUU	12	21	57	657	1200
LME12LUU	12	22	57	657	1200
LM16LUU	16	28	70	1230	2350
LME16LUU	16	26	70	1230	2350
LM20LUU	20	32	80	1400	2750
LME20LUU	20	32	80	1400	2750
LM30LUU	30	45	123	2490	5490
LME30LUU	30	47	123	2490	5490
LM40LUU	40	60	154	3430	8040
LME40LUU	40	62	154	3430	8040
LM60LUU	60	90	211	7650	20000
LME60LUU	60	90	211	7650	20000

Long Flange Bearing Configurations

LMF / LMEF Round Flange

A circular flange provides a symmetrical mounting interface. LM sizes cover 6–60 mm and LME sizes cover 8–60 mm.

LMK / LMEK Square Flange

The square flange provides four mounting corners and a straightforward orientation reference on the machine plate.

LMH Oval Flange

The oval flange reduces mounting width where a full round or square flange cannot be accommodated. Available sizes cover 6–30 mm.

Shaft dr	Round Flange	Square Flange	Oval Flange	C (N)	C₀ (N)
6 mm	LMF6LUU	LMK6LUU	LMH6LUU	320	520
8 mm	LMF8LUU / LMEF8LUU	LMK8LUU / LMEK8LUU	LMH8LUU	430	780
12 mm	LMF12LUU / LMEF12LUU	LMK12LUU / LMEK12LUU	LMH12LUU	650	1200
16 mm	LMF16LUU / LMEF16LUU	LMK16LUU / LMEK16LUU	LMH16LUU	1230	2350
20 mm	LMF20LUU / LMEF20LUU	LMK20LUU / LMEK20LUU	LMH20LUU	1400	2750
25 mm	LMF25LUU / LMEF25LUU	LMK25LUU / LMEK25LUU	LMH25LUU	1560	3140
30 mm	LMF30LUU / LMEF30LUU	LMK30LUU / LMEK30LUU	LMH30LUU	2490	5490
40 mm	LMF40LUU / LMEF40LUU	LMK40LUU / LMEK40LUU	-	3430	8040
60 mm	LMF60LUU / LMEF60LUU	LMK60LUU / LMEK60LUU	-	7650	20000

ST High-Temperature Linear Bearing Series

ST…UU and ST…UUB are identified in the available product data as high-temperature linear-motion bearing series. ST…UU covers shaft diameters from 8 mm to 100 mm, while ST…UUB covers 20 mm to 100 mm and provides higher listed dynamic and static load ratings.

The current ST specification data does not state the bearing material, maximum operating temperature, lubricant specification or seal type. These items must be confirmed for the actual temperature, speed, load, heating duration and surrounding atmosphere before an ST bearing is ordered.

Model	Bore (mm)	Outer D (mm)	Length L (mm)	Max. Travel (mm)	C (kN)	C₀ (kN)
ST8UU	8	15	24	14	0.98	0.27
ST20UU	20	32	45	32	4.12	1.57
ST20UUB	20	32	45	12	8.33	3.24
ST30UU	30	45	65	65	9.31	4.12
ST30UUB	30	45	65	27	18.7	8.14
ST50UU	50	72	100	120	12.6	8.82
ST50UUB	50	72	100	70	32.5	17.7
ST100UU	100	130	100	114	22.0	18.3
ST100UUB	100	130	100	58	43.9	36.8

Bearing Structure and Operating Principle

A cylindrical linear bearing contains load-carrying ball rows and internal return paths. As the bearing moves along the shaft, the balls circulate through the loaded and return sections, reducing sliding friction between the moving component and the guide shaft.

These bearings do not automatically eliminate all system clearance. Actual radial clearance and motion accuracy depend on the selected bearing clearance group, shaft diameter, shaft tolerance, housing fit and installation alignment.

Recirculating ball structure of precision linear bearing

Bearing Selection Factors

Shaft Diameter

The bearing bore must match the nominal shaft diameter. The shaft tolerance and bearing-clearance group must then be checked together.

Housing Interface

Outside diameter, bearing length, retaining grooves, flange shape, pitch-circle diameter and mounting holes determine installation compatibility.

Dynamic Load

The basic dynamic load rating is used in nominal life calculations. It is not a direct statement of the maximum moving load.

Static Load

The basic static load rating relates to permanent deformation under static loading and must be combined with an appropriate static safety factor.

Travel and Speed

Stroke, maximum speed, acceleration, duty cycle and direction changes affect lubrication, heat generation and expected service life.

Operating Environment

Dust, chips, moisture, chemicals and temperature determine the required seals, lubricant, material and maintenance interval.

Installation and Lubrication

Use a matched shaft: Shaft hardness, surface finish, diameter tolerance and straightness directly affect bearing travel and service life.
Control parallelism: Multi-shaft systems require accurate shaft spacing and parallel installation to prevent binding and uneven ball loading.
Apply housing force evenly: Pressing force should act on the bearing outer sleeve rather than the seals, cage or internal ball circuit.
Avoid dry operation: Lubrication must be selected according to speed, load, temperature, stroke, duty cycle and surrounding environment.
Protect against contamination: Wipers, seals or external covers should be considered where particles can enter the bearing.
Check operating condition: Increasing noise, resistance, temperature or clearance can indicate contamination, lubrication loss, shaft damage or alignment error.

Precision Linear Bearing FAQ

Q: Are LM and LME bearings interchangeable?

A: Not automatically. Bearings with the same shaft diameter may have different outside diameters, lengths, groove positions and tolerances. The complete dimensions must be checked against the existing housing.

Q: Does LUU mean that the bearing is longer?

A: Yes. LM…LUU and LME…LUU are long closed cylindrical bearings. Their increased length requires more housing space and provides additional ball-circulation contact compared with the related standard model.

Q: Which flange shape should be selected?

A: LMF and LMEF use a round flange, LMK and LMEK use a square flange, and LMH uses an oval flange. Selection should follow the mounting-hole pattern, available plate width, orientation and replacement dimensions.

Q: What is the difference between ST…UU and ST…UUB?

A: For the same bore size, ST…UUB has higher listed dynamic and static load ratings but a shorter maximum travel route. The final choice must also consider temperature, speed, lubricant, seals and required stroke.

Q: What maximum temperature can the ST series withstand?

A: The available specification identifies ST as a high-temperature series but does not provide a universal maximum temperature. The required continuous and peak temperatures, heating duration, lubricant and surrounding atmosphere must be submitted for technical confirmation.

Q: Does a precision linear bearing have zero backlash?

A: Not necessarily. System clearance depends on the bearing-clearance group, shaft diameter and tolerance, housing fit and installation. A standard bearing should not be described as automatically backlash-free.

Q: What information is required for selection?

A: Confirm the preferred series or existing model, shaft diameter, housing dimensions, quantity, moving load, static load, speed, stroke, mounting direction, working temperature and environmental conditions.

DLY Supply and Service

Zhejiang DLY Automation Manufacturing Co., Ltd. has more than 20 years of experience supplying linear-motion components. Standard cylindrical, long cylindrical and flange linear bearings are available across multiple metric shaft sizes, with steel-cage alternatives available for specified LM and LME models.

Standard products can be supplied from one piece and are covered by a one-year warranty. Delivery is normally 7–30 days depending on the model, quantity and stock status. Available stock can be arranged sooner after specification confirmation.