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When your linear axis binds, chatters, or wears unevenly, the culprit is almost always an undersized or mismatched slide bushing. Engineers, makers, and machine builders who demand repeatable, low-friction travel need a bearing that matches their shaft diameter exactly and holds tolerance under continuous cycling. These linear motion ball bearings are engineered for that purpose.
Each bearing consists of a hardened steel outer shell housing recirculating ball circuits that ride directly on a ground steel shaft. The lineup spans inner diameters from 3 mm (0.12 in) to 80 mm (3.15 in) and is offered in eight distinct series: standard closed (LM-UU), long closed (LM-LUU), galvanic-treated long (LM-LUU Galvanic), metric European (LME-UU), and four YTP-grade variants of the above, plus open-type (LM-UU-OP) and open-type YTP (LM-UU-OP YTP) for applications requiring side-loading or easy shaft insertion.
Typical use cases include CNC router Z-axis carriages, FDM 3D printer X/Y gantries, laser engraver linear stages, pick-and-place automation slides, and DIY linear actuators where smooth, low-noise travel is critical. Long-series (LUU) variants are favored for cantilevered loads, while open-type (OP) variants simplify installation on pre-assembled frames.
Available from LM3UU (3×7×10 mm) to LM80UU (80×120×140 mm), covering the most common shaft diameters used in CNC, robotics, and automation builds.
Choose from standard (UU), long (LUU), open (OP), European metric (LME), galvanic-treated, and YTP-grade variants — all sized to ISO/JIS dimensional standards.
Multiple rows of recirculating steel balls distribute load evenly around the shaft, reducing point contact stress and extending service life under repetitive linear cycling.
Outer shell and ball retainer are manufactured from hardened bearing steel, providing resistance to deformation under radial and moment loads typical in gantry and carriage applications.
The LM-UU-OP variants feature a longitudinal slot that allows installation onto a shaft without disassembling the frame — ideal for retrofit and maintenance scenarios.
YTP-grade bearings offer tighter internal clearance and improved running accuracy, suited for applications requiring reduced play and more consistent positioning repeatability.
| Bearing Type | Linear motion ball bushing (recirculating) |
|---|---|
| Series Available | LM-UU, LM-LUU, LM-LUU (Galvanic), LME-UU, LM-UU YTP, LM-LUU YTP, LM-UU-OP, LM-UU-OP YTP |
| Inner Diameter (ID) Range | 3 mm – 80 mm (0.12 in – 3.15 in) |
| Outer Diameter (OD) Range | 7 mm – 120 mm (0.28 in – 4.72 in) |
| Length Range | 10 mm – 209 mm (0.39 in – 8.23 in) |
| Shell Material | Hardened bearing steel |
| Ball Material | Hardened steel |
| Retainer Material | See variant options |
| Seal / Closure | Rubber seals both ends (UU); open slot one side (OP series) |
| Dimensional Standard | ISO / JIS B 1192 |
| Recommended Shaft Tolerance | h6 (ground or precision-drawn steel shaft) |
| Operating Temperature | See variant options |
| Lubrication | Factory-greased; re-lubrication recommended for extended duty cycles |
| Quantity per Order | 1 piece |
The LM-UU (standard) series is suitable for most balanced-load applications where the carriage is supported on both sides of the bearing. The LM-LUU (long) series has a greater axial length, which increases the number of ball circuits and improves load capacity and moment resistance — making it the better choice for cantilevered loads, single-rail setups, or applications with significant overhang.
YTP-grade bearings are manufactured to tighter internal clearance tolerances compared to standard grade. This results in reduced radial play, more consistent positioning, and lower vibration during high-speed traversal. YTP grade is recommended for precision CNC axes, optical stages, and any application where backlash or positional error must be minimized.
These bearings are designed for use with hardened, ground, or precision-drawn steel shafts. The recommended shaft tolerance is h6 for a proper sliding fit. Shafts made from soft materials such as aluminum or unhardened mild steel will wear rapidly under the ball contact load and are not recommended. Stainless steel shafts are compatible only if surface hardness meets the bearing manufacturer's minimum requirement.
The LM-UU-OP series features a longitudinal slot along the outer shell, allowing the bearing to be installed onto a shaft laterally without threading it from the end. This is particularly useful in retrofit situations, pre-assembled frames, or designs where the shaft cannot be removed. Note that the open slot slightly reduces radial load capacity compared to the closed equivalent.
The galvanic (electroplating) treatment applied to the LM-LUU Galvanic series adds a corrosion-resistant surface layer to the outer shell. This makes them more suitable for environments with moderate humidity, occasional water exposure, or light chemical contact — such as woodworking CNC machines, food-adjacent automation, or outdoor enclosures. They are not rated for full immersion or aggressive chemical environments.
The three numbers represent Inner Diameter × Outer Diameter × Length, all in millimeters. For LM8UU: ID = 8 mm (fits an 8 mm shaft), OD = 15 mm (housing bore must be 15 mm), Length = 24 mm. Always verify all three dimensions against your housing and shaft before ordering, as different series (UU vs LUU vs LME) use different OD and length values for the same shaft diameter.
All bearings are factory-greased and ready to install. For light-duty or intermittent use, the factory grease is typically sufficient for an extended period. For continuous-duty, high-speed, or high-load applications, re-lubrication with a lithium-based grease every 500–1,000 operating hours (or per your machine's maintenance schedule) is recommended to maintain smooth operation and extend service life.
The LME-UU series follows European metric dimensional standards (DIN / ISO) rather than the Japanese JIS standard used by the LM-UU series. For the same shaft diameter, LME bearings typically have a larger outer diameter and different length. If your housing was designed to European standards or you are sourcing replacement bearings for European-origin equipment, select the LME series. Always cross-reference the OD and length with your housing drawing.
