Why Lubrication Is Critical for Roller Guides
In a roller guide, the rolling elements roll along the raceways of the carriage and rail in line contact—this generates high surface pressures under load. The lubricating film separates the contacting surfaces, reduces friction, protects against pitting and corrosion, and, in the case of oil lubrication, also dissipates heat. Insufficient lubrication is the most common cause of failure: if the film breaks down, mixed friction occurs, and the guide fails well before its calculated rated service life.
Four Factors Affecting the Interval
There is no universal recommendation for relubrication—the interval depends on load, speed, temperature, and the environment (contamination, humidity). As a rough guideline, relubrication every 3 to 6 months is recommended under normal conditions; in hot, cold, dirty, or vibrating environments, weekly or even daily re-lubrication may be necessary. Grease remains the first choice for travel speeds up to about 2–3 m/s—above that, or in cases of high heat generation, a switch is made to oil or recirculating lubrication.
Mnemonic
Worked Example: Decoding a Grease Designation
Greases for roller guides are designated by an abbreviation in accordance with DIN 51825. Example: KP2K-30:
- K – Grease for rolling and plain bearings
- P – with EP/AW additives for increased load-carrying capacity
- 2 – NLGI Consistency Class 2 (standard for roller guides, medium consistency)
- K – maximum operating temperature +120 °C, tested resistance to water
- -30 – Lower operating temperature: −30 °C
For design, purchasing, and maintenance departments, “KP2K-30” refers to exactly the same lubricant—without the abbreviation, consistency and temperature range remain subject to negotiation.
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