THK ST20 LM Stroke Linear Ball Bushing
THK ST20 is a light‑load, long‑stroke linear ball bushing (LM Stroke type) designed for smooth, low‑friction linear and rotational motion with extended travel capability.
THK ST20 is a light‑load, long‑stroke linear ball bushing (LM Stroke type) designed for smooth, low‑friction linear and rotational motion with extended travel capability.
Official Specifications
| Parameter | Value |
|---|---|
| Inscribed Bore Diameter (dr) | 20 mm (+0.033 / +0.020) |
| Outer Diameter (D) | 32 mm (0 / -0.011) |
| Overall Length (L) | 45 mm (0 / -0.2) |
| Maximum Stroke | 54 mm |
| Basic Dynamic Load Rating (C) | 4.12 kN |
| Basic Static Load Rating (C₀) | 8.33 kN |
| Mass | 109 g |
| Retainer | Light alloy (high rigidity, lightweight) |
| Seal Type | None (open type; sealed version: ST20UU) |
| Oil Hole | Yes (for lubrication) |
| Material | Iron‑based outer cylinder; steel balls |
| Lubrication | Pre‑lubricated with anti‑rust oil; supports grease/oil lubrication |
| Operating Temperature | −15°C to 100°C (5°F to 212°F) |
| Accuracy Grade | Normal grade |
| Friction Coefficient (μ) | 0.0006 to 0.0012 |
Key Features
- Long‑stroke design (up to 54 mm) for extended linear travel
- Light alloy retainer for high‑speed, stable operation
- Precision‑ground raceways for minimal friction and high accuracy
- Thrust rings and snap rings prevent retainer over‑run
- Point‑contact ball design for ultra‑low friction
- Compatible with hardened precision shafts (recommended hardness ≥58 HRC)
Applications
Widely used in precision machinery, automation equipment, office machinery, measuring instruments, printing machines, and light‑duty linear motion systems requiring long‑stroke guidance.
