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When your linear axis wobbles, binds, or wears out prematurely, the root cause is almost always an undersized or mismatched bearing. Engineers, CNC builders, and robotics makers who demand repeatable, low-friction travel need a bearing that mounts rigidly and stays aligned under load — that's exactly what the LMKP square flange linear bearing series is designed to deliver.
Each LMKP linear bearing features a hardened steel outer shell with a square bolt-flange mounting plate, chrome steel ball complement, and a polymer ball retainer for smooth, quiet recirculation. Available in two body lengths: standard UU (closed both ends) and extended LUU for longer stroke support. The series spans inner diameters from 6 mm (0.24 in) to 60 mm (2.36 in), with outer diameters from 12 mm (0.47 in) to 90 mm (3.54 in) and body lengths from 19 mm (0.75 in) to 192 mm (7.56 in).
Typical applications include LMKP square flange linear bearings for CNC router Z-axis carriages, LMKP linear motion bearings for 3D printer gantry systems, and LMKP guide bearings for industrial pick-and-place automation and laser cutting machines.
| Series | LMKP (Square Flange, UU & LUU) |
|---|---|
| Inner Diameter (ID) | 6 mm – 60 mm (0.24 in – 2.36 in) |
| Outer Diameter (OD) | 12 mm – 90 mm (0.47 in – 3.54 in) |
| Body Length | 19 mm – 192 mm (0.75 in – 7.56 in) |
| Flange Type | Square, 4-bolt pattern |
| Seal Type | Dual-lip rubber (UU / LUU) |
| Ball Material | Chrome steel (GCr15) |
| Outer Shell Material | Carbon steel, hardened |
| Retainer Material | Polymer (nylon-type) |
| Lubrication | Grease pre-lubricated |
| Shaft Compatibility | Standard smooth round linear shaft |
| Bolt Circle / Flange Dimensions | See variant options |
| Dynamic Load Rating | See variant options |
| Static Load Rating | See variant options |
| Operating Temperature | –20°C to +80°C (–4°F to +176°F) |
The UU (standard) body is the right choice for compact axis designs where space is limited. The LUU (long) body provides a longer ball contact zone, which increases load capacity and improves shaft guidance — ideal for cantilevered loads, longer strokes, or applications where shaft deflection is a concern. If in doubt, the LUU version offers more stability at a modest size increase.
The shaft diameter must match the bearing's inner diameter (ID) exactly. For example, an LMKP12UU requires a 12 mm diameter smooth linear shaft. Using an undersized shaft will cause play and premature wear; an oversized shaft will not fit. Always verify your shaft OD with a micrometer before ordering.
Yes. The LMKP series follows ISO/JIS LMK-series outer dimensions, so these bearings are dimensionally compatible with standard LMK square flange housings and pillow blocks. Always cross-reference the outer diameter and flange bolt pattern of your existing housing before installing.
LMKP linear bearings are designed primarily for axial (along-shaft) linear motion with radial loads applied perpendicular to the shaft. They are not intended for pure thrust or heavy side-impact loads. For applications with significant side loads, use two bearings spaced apart along the shaft to distribute the moment load, or consider a supported rail system.
The outer shell and balls are carbon/chrome steel, which offers moderate corrosion resistance when properly greased. The dual-lip rubber seals help retain lubricant and exclude moisture. For consistently wet or corrosive environments, we recommend applying a compatible bearing grease regularly and considering stainless-shaft pairings. These bearings are not rated for full submersion or highly corrosive chemical exposure.
Slide the bearing onto the linear shaft from one end — never press or hammer directly on the seal faces. Align the square flange with your mounting surface and secure with four bolts tightened evenly in a cross pattern to avoid distorting the housing. Ensure the shaft is clean, lightly oiled, and free of burrs before installation. Apply a small amount of compatible grease to the shaft if the bearing is not pre-lubricated for your application.
LMK refers to the square flange linear bearing housing/block, while LMKP designates the specific bearing insert with a square flange integrated into the bearing body itself. LMKP bearings are self-contained units — the flange is part of the bearing — making them easier to install directly without a separate housing. Both follow the same outer dimension standards.
