LM Series Linear Bearing for Round Shaft Linear Motion
LM series linear bearing is a standard round shaft bearing used with hardened linear shafts to provide smooth, low-friction straight-line motion. It uses circulating steel balls inside the bearing body, allowing the bearing to move along the shaft with stable guidance and easy installation.
DLY supplies LM series linear bearings in common models such as LM10UU, LM12UU, LM16UU, LM20UU, LM25UU and LM30UU. The model number usually indicates the matching shaft diameter. For example, LM20UU is used with a 20mm linear shaft, while UU means the bearing has double-sided seals.
LM linear bearings are widely used in CNC machines, packaging equipment, automation systems, 3D printers, woodworking machines, inspection devices and shaft-based linear guide assemblies. DLY can also provide matching linear shafts, bearing blocks, shaft supports and supported shaft rail products for complete motion systems.
What Is an LM Series Linear Bearing?
An LM series linear bearing is a cylindrical linear motion bearing designed to slide along a round linear shaft. Unlike rotary bearings, LM bearings are used for straight-line movement. They are usually installed inside bearing housings, bearing blocks, machine frames or custom guide structures.
The bearing works together with a hardened and polished shaft. When the shaft surface, bearing model, housing fit and alignment are correct, the bearing can provide smooth movement with relatively low friction. This makes it suitable for compact and economical linear motion systems.
For reliable operation, the bearing should not be selected alone. The shaft diameter, shaft hardness, surface finish, housing bore, lubrication condition and load direction should be checked together before ordering.
How to Read LM Linear Bearing Model Numbers
LM bearing model numbers are simple, but every part of the code affects selection. Understanding the model code helps avoid wrong shaft matching, wrong seal type or unsuitable installation structure.
| Model Code | Meaning | Example |
|---|---|---|
| LM | Linear Motion bearing series for round shaft guidance. | LM20UU |
| Number | The matching shaft diameter in millimeters. | 20 = 20mm linear shaft |
| UU | Double-sided seals for dust protection and grease retention. | LM20UU |
| LUU | Long type with double-sided seals. | LM20LUU |
| C | Increased clearance type for tolerance compensation. | LM20CUU |
| AJ / CAJ | Adjustable clearance type; CAJ provides increased clearance adjustment. | LM20AJ / LM20CAJ |
| OP / COP | Open type; COP is open type with increased clearance. | LM20OP / LM20COP |
| LME | Thin-wall linear bearing series for compact or lightweight housings. | LME20UU |
Example: LM20UU
LM20UU means LM linear motion bearing series + 20mm shaft diameter + double-sided sealed design. It should be used with a 20mm hardened linear shaft and a suitable bearing housing or bearing block.
Common LM Series Linear Bearing Models
The most direct way to select an LM linear bearing is to start from the shaft diameter. The bearing inner diameter must match the round shaft. For replacement, the outer diameter and bearing length should also be checked against the original housing.
| Common Model | Matching Shaft Diameter | Typical Use | Selection Note |
|---|---|---|---|
| LM6UU | 6 mm | Small devices, compact guide systems | Check housing space carefully. |
| LM8UU | 8 mm | 3D printers, light automation | Common for small shaft assemblies. |
| LM10UU | 10 mm | Light-duty automation equipment | Confirm shaft accuracy and mounting alignment. |
| LM12UU | 12 mm | Small CNC, sliding tables, guide units | Useful for compact but stable movement. |
| LM16UU | 16 mm | General automation and machinery | Common middle-size bearing choice. |
| LM20UU | 20 mm | CNC, packaging, transfer mechanisms | Popular for medium-duty shaft systems. |
| LM25UU | 25 mm | Medium machinery and larger guide structures | Check load and shaft deflection. |
| LM30UU | 30 mm | Larger automation and machine frames | Confirm bearing block and shaft support together. |
LM Series Specification and Dimension Reference
The specification images below show LM and LME series model designations, shaft diameters, ball circuits, weight, tolerance information and main dimensions. For replacement or batch purchasing, check both the bearing model and the housing dimensions before ordering.
LM, LME, Adjustable and Open Type Selection
LM series linear bearings are available in several structures. The correct type depends on housing design, clearance requirement, installation accuracy, shaft support method and working environment.
| Type | Key Feature | Best For | Selection Note |
|---|---|---|---|
| LM…UU | Standard sealed type | General shaft guide systems | Common choice for normal linear bearing applications. |
| LM…C / LME…C | Increased clearance | Tolerance compensation | Useful when mounting accuracy is not very strict. |
| LME…UU | Thin-wall structure | Compact housings and lightweight structures | Do not replace LM directly without checking dimensions. |
| LM…AJ / LME…AJ | Adjustable clearance | Fine adjustment during installation | Requires suitable housing and careful adjustment. |
| LM…CAJ / LME…CAJ | Adjustable type with increased clearance | Systems needing wider clearance adjustment | Confirm preload and sliding resistance after assembly. |
| LM…OP / LME…OP | Open type structure | Supported shafts or custom bearing housings | Useful when the shaft needs additional support or clearance space. |
| LM…COP / LME…COP | Open type with increased clearance | Flexible installation and tolerance compensation | Check shaft support structure before selection. |
| LM…LUU | Long double-sealed type | Higher moment stability than standard short type | Used when a longer bearing contact length is needed. |
LM Series vs LME Series Linear Bearings
LM and LME bearings may look similar, but the outer dimensions and housing requirements can be different. For replacement, do not judge only by shaft diameter. The outer diameter, bearing length and housing bore should also be confirmed.
| Item | LM Series | LME Series |
|---|---|---|
| Structure | Standard outer sleeve structure | Thin-wall outer sleeve structure |
| Housing Fit | Common in standard bearing blocks and rigid housings | Common in compact or lightweight housings |
| Selection Logic | General-purpose round shaft linear motion | Space-limited or lightweight shaft systems |
| Replacement Note | Check shaft diameter, outer diameter and length | Check housing bore carefully before replacement |
FAQ About LM Series Linear Bearing
Q: What is an LM series linear bearing?
A: An LM series linear bearing is a round shaft linear motion bearing. It uses circulating steel balls to move along a hardened linear shaft and is used for straight-line movement in automation, CNC, packaging and guide systems.
Q: What does LM20UU mean?
A: LM20UU means LM linear motion bearing series, 20mm shaft diameter and double-sided sealed design. It should be matched with a 20mm hardened linear shaft.
Q: What shaft should be used with LM linear bearings?
A: LM linear bearings should be used with hardened, ground and polished round linear shafts. The shaft diameter must match the bearing model, such as LM16UU with a 16mm shaft and LM20UU with a 20mm shaft.
Q: What is the difference between LM and LME linear bearings?
A: LM is a standard linear bearing series. LME is a thin-wall linear bearing series for compact or lightweight housings. They should not be replaced with each other without checking outer diameter, length and housing size.
Q: What is the difference between UU and OP type?
A: UU means double-sided sealed type, which helps protect the bearing from dust and retain grease. OP means open type, which is used when the bearing must work with a supported shaft structure or a special housing design.
Q: When should I choose adjustable linear bearings?
A: Adjustable linear bearings are suitable when clearance needs to be fine-tuned during installation. They require a suitable housing and careful adjustment to avoid excessive preload or sliding resistance.
Q: Can LM bearings be used with supported shafts?
A: For supported shaft rail structures, open type linear bearings are usually considered because the shaft support needs clearance. Standard closed LM-UU bearings are more suitable for unsupported round shafts or bearing block assemblies.
Q: What information is needed for quotation?
A: Please provide the bearing model, shaft diameter, quantity, sealed or open type requirement, housing type, application, working environment and whether matching shafts or bearing blocks are needed.
Contact DLY for LM Linear Bearing Selection
If you need LM series linear bearings for round shaft guide systems, DLY can help confirm model selection, shaft diameter matching, seal type, housing structure and related linear motion components.
For faster quotation, please send the bearing model, shaft diameter, quantity, application, working environment and whether matching linear shafts, shaft supports or bearing blocks are required.
WhatsApp: +86 166 0578 8856
Email: dlyexport2@dlybearing.com
Hot Tags: lm series linear bearing, China lm series linear bearing manufacturers, suppliers, factory
