THK LM20UUOP Linear Ball Bushing
The LM20UUOP is an open‑type linear ball bushing from THK’s standard LM‑UU seriesTHK. It features a resin retainer, UU dust seals, and an open‑slot design for easy shaft installation. Engineered for smooth, low‑friction linear motion with stable radial load support, it is widely used in automation equipment, precision machinery, and general linear guidance systems.
The LM20UUOP is an open‑type linear ball bushing from THK’s standard LM‑UU series. It features a resin retainer, UU dust seals, and an open‑slot design for easy shaft installation. Engineered for smooth, low‑friction linear motion with stable radial load support, it is widely used in automation equipment, precision machinery, and general linear guidance systems.
Official Specifications
| Parameter | Value | Unit |
|---|---|---|
| Inner bore diameter (dr) | 20 | mm |
| Outer diameter (D) | 32 | mm |
| Overall length (L) | 42 | mm |
| Number of ball rows | 4 | — |
| Basic dynamic load rating (C) | 863 | N |
| Basic static load rating (C₀) | 1,370 | N |
| Mass | 69 | g |
| Bore diameter tolerance (High grade) | 0 / –0.007 | mm |
| Outer diameter tolerance (High grade) | 0 / –0.016 | mm |
| Length tolerance | ±0.20 | mm |
| Max eccentricity | 15 | μm |
| Radial clearance (High grade) | –6 | μm |
| Retainer material | Resin | — |
| Outer sleeve material | High‑carbon chromium bearing steel | — |
| Ball material | Hardened steel | — |
| Operating temperature range | –10°C to +80°C | °C |
| Seal type | UU (double lip seals) | — |
| Open slot angle | 60° | ° |
| Lubrication | Pre‑lubricated with rust‑preventive oil; grease recommended | — |
Key Features
- Open‑type design: 60° open slot enables easy mounting onto shafts and simplifies maintenance in confined spaces.
- UU double‑lip seals: Effective dust and moisture protection, extending service life in harsh environments.
- Resin retainer: Lightweight, low‑noise operation with stable ball guidance.
- High precision: Strict dimensional tolerances ensure smooth motion and interchangeability.
- Standard dimensions: Fully compatible with THK LM‑series shafts and other metric linear motion systems.
Official Notes
- Designed exclusively for linear motion; not for pure rotational or moment loads. Use multiple bushings on a single shaft to resist moment loadsTHK.
- Recommended lubrication: THK AFB‑L grease or equivalent lithium‑based grease.
- Shaft requirements: Surface hardness ≥58 HRC, surface roughness Ra ≤0.4 μm.
- Note: LM20‑OP series (including LM20UUOP) is scheduled for discontinuation as of January 23, 2026; refer to THK’s official replacement list for alternatives.
