Square Flange Linear Bearing for Plate-Mounted Shaft Guidance
Square flange linear bearings are used with round linear shafts to support smooth straight-line movement. The bearing body slides along the shaft through internal ball circulation, while the square flange provides a simple four-hole mounting surface for machine plates, moving carriages and compact mechanical frames.
Compared with a standard cylindrical linear bearing, the square flange type does not need a separate housing block. It can be mounted directly from the flange face, which helps simplify the structure when the bearing must be fixed to a flat plate or rectangular moving platform.
DLY supplies LMK, LMKC, LMEK and LMEKC square flange linear bearings in common bore sizes. Matching linear shafts, shaft supports and related linear motion components can also be supplied for complete shaft guide assemblies.
Basic Product Information
The square flange linear bearing is selected by shaft bore size, bearing series, flange mounting dimensions and load requirement. For replacement projects, both the model number and the actual mounting dimensions should be checked before ordering.
| Product Name | Square Flange Linear Bearing |
| Common Series | LMK, LMKC, LMEK and LMEKC |
| Matched Shaft | Round linear shaft, chrome plated shaft or hardened linear shaft |
| Mounting Method | Four-hole square flange mounting on plate, bracket or moving table |
| Available Support | Model selection, shaft matching, replacement checking and non-standard customization |
Key Features of Square Flange Linear Bearings
Four-Hole Square Flange Mounting
The square flange allows the bearing to be fixed directly to a machine plate, bracket or moving carriage. This helps simplify the assembly structure because no separate bearing housing is required. It is especially suitable for rectangular plates and compact mechanical frames.
Smooth Motion on Round Linear Shafts
The internal ball circulation structure supports low-friction movement along a round linear shaft. During repeated linear motion, the bearing helps the moving part travel smoothly while reducing direct sliding friction between the shaft and bearing body.
Clear Mounting Reference for Equipment Design
The square flange provides a clear reference surface and four mounting holes, making it easier to design the hole layout on a moving platform or fixed plate. This is useful when the machine structure requires stable positioning and easy installation.
Suitable for Replacement and Matched Shaft Assemblies
For replacement projects, customers can compare the model number and mounting dimensions with the original bearing. DLY can also help match the square flange linear bearing with linear shafts, shaft supports and related linear motion components for complete shaft guide assemblies.
Load Rating and Bore Size Table
The load rating table below converts the main data from the flange linear bearing specification chart into text form. It helps compare LMK and LMEK square flange models by shaft bore size, ball row quantity, weight, allowable shaft diameter deviation, dynamic load rating and static load rating.
| Square Flange Model | Inner diameter dr (mm) | Ball Rows | Weight (g) | Allowable Shaft Diameter Deviation (μm) | Dynamic Load C (N) | Static Load Co (N) |
|---|---|---|---|---|---|---|
| LMK6UU | 6 | 4 | 26.5 | -5 | 200 | 260 |
| LMK8SUU | 8 | 4 | 34 | -5 | 170 | 220 |
| LMK8UU | 8 | 4 | 40 | -5 | 260 | 400 |
| LMK10UU | 10 | 4 | 78 | -5 | 370 | 540 |
| LMK12UU | 12 | 4 | 76 | -5 | 410 | 590 |
| LMK13UU | 13 | 4 | 94 | -7 | 500 | 770 |
| LMK16UU | 16 | 5 | 134 | -7 | 770 | 1170 |
| LMK20UU | 20 | 5 | 180 | -9 | 860 | 1370 |
| LMK25UU | 25 | 6 | 340 | -9 | 980 | 1560 |
| LMK30UU | 30 | 6 | 460 | -9 | 1560 | 2740 |
| LMK40UU | 40 | 6 | 1054 | -13 | 2150 | 4010 |
| LMK50UU | 50 | 6 | 2200 | -13 | 3820 | 7930 |
| LMK60UU | 60 | 6 | 2960 | -16 | 4700 | 9990 |
LMEK Series Load Rating Reference
LMEK models are often checked separately because their body dimensions and model codes differ from standard LMK series. The table below helps compare common LMEK square flange linear bearings by bore size and load rating.
| LMEK Model | Shaft Bore dr (mm) | Ball Rows | Weight (gf) | Allowable Shaft Diameter Deviation (μm) | Dynamic Load C (N) | Static Load Co (N) |
|---|---|---|---|---|---|---|
| LMEK8UU | 8 | 4 | 44 | -5 | 260 | 400 |
| LMEK12UU | 12 | 4 | 86 | -5 | 500 | 770 |
| LMEK16UU | 16 | 5 | 120 | -7 | 570 | 890 |
| LMEK20UU | 20 | 5 | 184 | -9 | 860 | 1370 |
| LMEK25UU | 25 | 6 | 335 | -9 | 980 | 1560 |
| LMEK30UU | 30 | 6 | 545 | -9 | 1560 | 2740 |
| LMEK40UU | 40 | 6 | 1185 | -13 | 2150 | 4010 |
| LMEK50UU | 50 | 6 | 1730 | -13 | 3820 | 7930 |
| LMEK60UU | 60 | 6 | 3180 | -16 | 4700 | 9990 |
Flanged linear bearing load rating, bore size and model reference chart
Mounting Dimension Terms
Before ordering a square flange linear bearing, the mounting dimensions should be checked against the machine plate or existing bearing. The most important values are the shaft bore size, bearing length, flange size, pitch circle diameter and mounting hole size.
| Dimension Symbol | Meaning | Why It Matters |
|---|---|---|
| dr | Bearing bore size / matched shaft diameter | The bearing bore must match the linear shaft size. |
| D | Outer diameter of bearing body | Affects clearance around the bearing sleeve. |
| L | Bearing length | Confirms available axial space in the machine. |
| D1 | Flange outside dimension | Determines whether the flange fits the mounting plate. |
| PCD / K / H | Mounting hole layout dimensions | Used to design or verify screw hole positions. |
| d1 × d2 × h | Mounting hole and counterbore size | Helps confirm screw size and installation clearance. |
Common LMK Mounting Dimensions
The table below lists common LMK square flange linear bearing dimensions used for mounting plate design and replacement checking. For strict replacement, confirm the full drawing and actual sample dimensions before ordering.
| Model | Shaft Bore (mm) | D (mm) | L (mm) | D1 (mm) | H (mm) | PCD (mm) | K (mm) | Mounting Hole d1 × d2 × h |
|---|---|---|---|---|---|---|---|---|
| LMK6UU | 6 | 12 | 19 | 28 | 5 | 20 | 22 | 3.4 × 6.5 × 3.3 |
| LMK8SUU | 8 | 15 | 17 | 32 | 5 | 24 | 25 | 3.4 × 6.5 × 3.3 |
| LMK8UU | 8 | 15 | 24 | 32 | 5 | 24 | 25 | 3.4 × 6.5 × 3.3 |
| LMK10UU | 10 | 19 | 29 | 40 | 6 | 29 | 30 | 4.5 × 8 × 4.4 |
| LMK12UU | 12 | 21 | 30 | 42 | 6 | 32 | 32 | 4.5 × 8 × 4.4 |
| LMK16UU | 16 | 28 | 37 | 48 | 6 | 38 | 37 | 4.5 × 8 × 4.4 |
| LMK20UU | 20 | 32 | 42 | 54 | 8 | 43 | 42 | 5.5 × 9.5 × 5.4 |
| LMK25UU | 25 | 40 | 59 | 62 | 8 | 51 | 50 | 5.5 × 9.5 × 5.4 |
| LMK30UU | 30 | 45 | 64 | 74 | 10 | 60 | 58 | 6.6 × 11 × 6.5 |
| LMK40UU | 40 | 60 | 80 | 96 | 13 | 78 | 75 | 9 × 14 × 8.6 |
| LMK50UU | 50 | 80 | 100 | 116 | 13 | 98 | 92 | 9 × 14 × 8.6 |
| LMK60UU | 60 | 90 | 110 | 134 | 18 | 112 | 106 | 11 × 17.5 × 10.8 |
Common LMEK Mounting Dimensions
For LMEK models, the dimension structure differs from standard LMK models. The table below provides quick reference data for common LMEK square flange linear bearings.
| Model | Shaft Bore (mm) | D (mm) | L (mm) | D1 (mm) | H (mm) | PCD (mm) | K (mm) | Mounting Hole d1 × d2 × h |
|---|---|---|---|---|---|---|---|---|
| LMEK8UU | 8 | 16 | 25 | 32 | 5 | 24 | 25 | 3.4 × 6.5 × 3.3 |
| LMEK12UU | 12 | 22 | 32 | 42 | 6 | 32 | 32 | 4.5 × 8 × 4.4 |
| LMEK16UU | 16 | 26 | 36 | 46 | 6 | 36 | 35 | 4.5 × 8 × 4.4 |
| LMEK20UU | 20 | 32 | 45 | 54 | 8 | 43 | 42 | 5.5 × 9.5 × 5.4 |
| LMEK25UU | 25 | 40 | 58 | 62 | 8 | 51 | 50 | 5.5 × 9.5 × 5.4 |
| LMEK30UU | 30 | 47 | 68 | 76 | 10 | 62 | 60 | 6.6 × 11 × 6.5 |
| LMEK40UU | 40 | 62 | 80 | 98 | 13 | 80 | 75 | 9 × 14 × 8.6 |
| LMEK50UU | 50 | 75 | 100 | 112 | 13 | 94 | 88 | 9 × 14 × 8.6 |
| LMEK60UU | 60 | 90 | 125 | 134 | 18 | 112 | 106 | 11 × 17.5 × 10.8 |
Square flange linear bearing mounting dimensions and flange drawing
How to Choose the Correct Square Flange Linear Bearing
A correct selection should start from the shaft diameter, but it should not stop there. The bearing length, flange size, mounting hole layout, load direction, shaft support span and installation accuracy all affect the final running condition.
| Selection Step | What to Check | Practical Reminder |
|---|---|---|
| 1. Confirm shaft diameter | Match the bearing bore size with the linear shaft diameter. | For example, LMK12UU matches a 12mm shaft. |
| 2. Check mounting space | Check D, L, D1, PCD, K and hole size. | Useful when replacing an old bearing or designing a new plate. |
| 3. Review load condition | Compare dynamic load C and static load Co. | For heavier platforms, check load direction and bearing spacing carefully. |
| 4. Check shaft quality | Shaft hardness, surface finish and straightness. | Poor shaft quality can cause noise, wear or short service life. |
| 5. Confirm working environment | Dust, chips, moisture, speed and lubrication condition. | Dust protection is important for woodworking, cutting and packaging equipment. |
Square Flange, Round Flange and Oval Flange Comparison
Different flange shapes are selected according to the mounting structure. The square flange type is especially suitable for flat plates, rectangular frames and moving tables where four-corner fixing is convenient.
| Flange Type | Typical Series | Mounting Style | Best Used For |
|---|---|---|---|
| Square flange | LMK, LMKC, LMKE, LMKEC | Four-hole square flange | Rectangular plates, carriage platforms, brackets and machine frames. |
| Round flange | LMF, LMEF | Circular flange mounting | General flange mounting where circular support is preferred. |
| Oval flange | LMH, LMHE | Narrow two-side flange structure | Compact installation where side width is limited. |
Applications
Square flange linear bearings are commonly used where a round shaft guide system needs a direct mounting interface. Their four-hole flange design makes them suitable for plate-mounted movement rather than only loose bearing installation.
| Application | How the Bearing Is Used | Selection Reminder |
|---|---|---|
| Moving carriage plates | The square flange is bolted to a moving plate, and the bearing moves along the shaft. | Check plate flatness and hole position accuracy. |
| Small automation axes | Used for short-stroke pushing, lifting, transferring or positioning mechanisms. | Confirm bearing spacing and load direction. |
| Packaging machinery | Supports repetitive guide movement in compact machine structures. | Add dust protection and maintain lubrication regularly. |
| Testing and measuring devices | Guides small platforms that require controlled straight-line movement. | Avoid side load and misalignment. |
| Custom linear shaft assemblies | Combined with shafts, shaft supports and brackets to build a shaft guide unit. | Select bearing, shaft and support together to avoid mismatch. |
DLY Supply Capability for Square Flange Linear Bearings
DLY supplies square flange linear bearings as individual components or as part of a matched linear shaft system. For customers who are building or replacing a shaft-guided motion unit, DLY can help confirm the bearing model, shaft diameter, support method and related components together.
DLY flange linear bearing series for different shaft diameters
DLY can help customers confirm the correct square flange linear bearing model before ordering. For LMK, LMKC, LMKE and LMKEC series, similar-looking bearings may have different bore sizes, flange dimensions or mounting hole layouts. By checking the shaft diameter, model code and key dimensions together, we help reduce the risk of selecting an incorrect replacement or mismatched bearing.
For customers building a complete shaft guide system, DLY can supply square flange linear bearings together with matched linear shafts, chrome plated shafts and shaft supports. Selecting the bearing and shaft together helps avoid problems such as bore size mismatch, poor running smoothness or unstable installation after assembly.
Standard square flange linear bearings can be ordered from 1 piece, making them suitable for equipment maintenance, sample testing, repair replacement and small batch projects. For machinery builders and automation equipment manufacturers, DLY can also support regular model supply and batch procurement according to project demand.
Before quotation or shipment, customers can send the shaft size, stroke length, load direction, mounting space, working environment and existing bearing photos or drawings. These details help DLY confirm the model more accurately and provide a more practical selection suggestion before purchase.
FAQ
Q: What is a square flange linear bearing?
A: A square flange linear bearing is a linear bearing with a square mounting flange. It is used with a round linear shaft to guide smooth straight-line movement and can be fixed directly to a plate or carriage through the four flange holes.
Q: What is the difference between LMK and LMF linear bearings?
A: LMK is a square flange linear bearing, while LMF is a round flange linear bearing. Both work with round linear shafts, but their flange shapes and mounting hole layouts are different. LMK is usually easier to mount on rectangular plates and moving carriages.
Q: How do I choose the correct LMK linear bearing size?
A: Start with the shaft diameter. For example, LMK12UU matches a 12mm shaft. Then check the bearing length, flange size, PCD, mounting hole size, load rating and available installation space.
Q: Can a square flange linear bearing be used with any round shaft?
A: It should be used with a shaft that matches the bearing bore size and has suitable hardness, surface finish and straightness. A soft, rough or bent shaft can cause noise, wear or poor movement.
Q: Why does a square flange linear bearing jam or make noise?
A: Common causes include shaft misalignment, poor parallelism, excessive side load, incorrect bore size, dirty shaft surface, lack of lubrication or foreign particles entering the bearing. Checking the shaft, mounting plate and lubrication condition usually helps locate the problem.
Q: Can DLY help replace another brand's LMK bearing?
A: Yes. Please provide the old model number, photos, shaft diameter and key mounting dimensions. If possible, also provide the drawing or measured dimensions of D, L, D1, PCD and mounting holes.
Q: What is the MOQ for square flange linear bearings?
A: For standard models, MOQ can start from 1 piece. This is useful for sample testing, maintenance replacement and small quantity orders. For larger quantities or special requirements, the quotation can be confirmed according to the model and quantity.
Q: Can DLY supply the bearing together with the linear shaft?
A: Yes. DLY can supply square flange linear bearings together with matched linear shafts, shaft supports and related linear motion components, helping customers build a complete shaft guide system.
Q: What information is needed for a quotation?
A: Please provide the model, shaft diameter, quantity, application, load direction, stroke length, working environment and any drawing or replacement sample information. This helps confirm the correct model and avoid dimension mismatch.
Q: How long does delivery take?
A: Delivery time depends on model, stock status, quantity and whether matching shafts or non-standard customization are required. Standard models are usually easier to arrange than customized assemblies.
Need Square Flange Linear Bearing Selection Support?
Send us your shaft diameter, bearing model, mounting dimensions, load direction, stroke length, quantity and application details. DLY can help confirm a suitable square flange linear bearing and matching linear shaft solution.
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