Linear Guides: Four guides covering selection, accuracy, preload and accessories
Four guides covering selection, accuracy, preload and accessories
In a linear axis the two do different jobs: the screw drives and positions, the guide carries and steers. Asking the screw to guide as well puts side moments on the balls and cuts life dramatically — the most common design error.
Guides take radial load, reverse-radial load and lateral load, plus the moment produced by any offset.
Note: guide accuracy is not C0–C3 — that is the screw code. Guides use five grades:
| Grade | Meaning | Typical use |
|---|---|---|
| N | Normal | Transport, general automation |
| H | High | General machinery, packaging |
| P | Precision | CNC, laser processing |
| SP | Super precision | Semiconductor, precision metrology |
| UP | Ultra precision | Ultra-precision metrology, optical alignment |
Running parallelism is tabulated by rail length — look it up for your actual rail length rather than relying on the grade letter alone.
| Preload | Radial clearance | Use |
|---|---|---|
| ZF | Slight clearance | Light load, smoothest travel |
| Z0 | No preload | General transport and feed |
| Z1 | Light preload | Machines with mild vibration or shock |
| Z2 | Medium preload | Machining equipment needing stiffness |
| Z3 | Heavy preload | Heavy cutting, large inertia |
More preload means more stiffness but higher drag, more heat and shorter life. Z1 covers most general machinery.
Guide life is stated as travel distance:
The equivalent load combines radial, reverse-radial and lateral components. With multiple blocks on one rail, calculate each block and check the worst case. The static load rating Co covers shock and permanent deformation, usually with a safety factor of 1–2.
| Type | Character | Use |
|---|---|---|
| Flanged | Wide mounting face, low height | Top-down mounting, limited height |
| Square (standard) | Balanced stiffness, high capacity | General purpose, most common |
| Long | Higher load and moment capacity | Large offset loads, cantilevered structures |
No. C3/C5/C7/C10 are ball screw codes. Linear guides use N/H/P/SP/UP. Mixing the two leads to buying something other than what you specified.
Two blocks per rail is typical. For heavy, offset or cantilevered loads, add blocks or move to long blocks — that works better than simply widening the rail.
Not always. Preload raises stiffness but also drag and heat, and shortens life. Z1 is usually enough for general machinery; Z2/Z3 belong in heavy cutting.
Yes. We supply both, so a screw and a guide can be paired from different makers without waiting for a consolidated shipment.