Seals in linear guides

2024-06-10

Seals are a key detail if you want long-lasting linear guides.

If particles get inside the carriage, you risk:

• Wear (dirt works like sandpaper)
• Ball damage
• Pitting
• Jamming
• Lubrication failure

All of which = shorter lifespan.

We distinguish between end seals and longitudinal seals.

End seals

These are usually the most effective – and yes, they often add more friction. But sometimes, application needs decide which seal to use. Many brands offer options with different properties:

Low-friction seals:

Great for clean environments like labs or manual setups. They gently wipe the surface and leave more grease behind, offering longer lube intervals. But they can’t handle heavy contamination.

Standard seals:

Good all-rounders. Well-designed ones offer solid protection and long service intervals.

Double-lip seals:

These have one lip to keep dirt out and another to keep grease in. They press harder against the rail for the best protection but require more frequent lubrication. Escaping grease typically gathers at the rail’s end points.

Longitudinal seals

Some carriages are open on the bottom, allowing debris to enter from below – especially if mounted upside down. Some brands offer add-on longitudinal seals, while others include them as standard.

A few even have internal longitudinal seals above the ball rows – guarding against dirt sneaking in via plug holes or mounting screws.

Another important design aspect: seals must maintain contact even as they wear – which means they need to be elastic and spring-loaded against the surface.

Also, seal materials should remain flexible over time. On some models, you can even replace seals during service to extend the carriage’s life.

Here's a helpful video on this from Carry Lindholm at Bosch Rexroth: