CMRT CMRT Lubrication and Tribology 2 — Questions and Answers
Question 1: Which contamination type is considered the number one destroyer of lubricated components in industrial machinery?
- Water contamination
- Solid particle contamination (Correct answer)
- Air entrainment
- Oxidation byproducts
Correct answer: Solid particle contamination
Solid particle contamination (dirt, wear debris, and dust) is recognized as the primary cause of lubricated component failures because particles accelerate wear and damage surfaces.
Question 2: What does the ISO cleanliness code (e.g., ISO 16/14/11) measure in oil analysis?
- The concentration of additive packages in the lubricant
- The number of particles per milliliter at three different size thresholds (Correct answer)
- The oxidation stability rating of the lubricant
- The percentage of water contamination in the oil
Correct answer: The number of particles per milliliter at three different size thresholds
The ISO 4406 cleanliness code reports particle counts per milliliter at three size thresholds (4µm, 6µm, and 14µm), with each number representing a range of particle concentrations.
Question 3: What is the primary advantage of using synthetic lubricants over conventional mineral oils in high-temperature applications?
- Synthetic oils are always less expensive than mineral oils
- Synthetic oils offer better oxidation stability and wider operating temperature ranges (Correct answer)
- Synthetic oils require more frequent change intervals
- Synthetic oils are universally compatible with all seal materials
Correct answer: Synthetic oils offer better oxidation stability and wider operating temperature ranges
Synthetic lubricants provide superior oxidation stability, thermal stability, and maintain useful viscosity across a wider temperature range compared to conventional mineral oils.
Question 4: What is 'over-greasing' a bearing and why is it harmful?
- Applying grease too frequently but in small quantities, which is actually beneficial
- Applying excessive grease that causes elevated temperatures, churning, and premature bearing failure (Correct answer)
- Using a grease with too high a viscosity for the application
- Mixing incompatible grease types in the bearing housing
Correct answer: Applying excessive grease that causes elevated temperatures, churning, and premature bearing failure
Over-greasing packs the bearing housing with excess grease, causing the rolling elements to churn the lubricant, generating heat, and ultimately leading to premature bearing failure.
Question 5: Which property of a lubricant is described by its 'flash point'?
- The temperature at which the oil ignites and sustains combustion
- The lowest temperature at which the oil vaporizes sufficiently to ignite briefly when exposed to a flame (Correct answer)
- The temperature at which the oil begins to oxidize rapidly
- The temperature at which the oil loses all lubricating properties
Correct answer: The lowest temperature at which the oil vaporizes sufficiently to ignite briefly when exposed to a flame
The flash point is the lowest temperature at which vapors above the oil will briefly ignite when exposed to an open flame, making it an important safety and fire-hazard indicator.
Question 6: What does a rising trend of iron (Fe) particles in an oil analysis report most likely indicate?
- Normal lubricant additive depletion
- Wear occurring in iron or steel components such as gears, bearings, or cylinder walls (Correct answer)
- Contamination from the external environment
- Oxidation of the base oil
Correct answer: Wear occurring in iron or steel components such as gears, bearings, or cylinder walls
A rising iron trend in oil analysis indicates that iron or steel components (gears, bearings, shafts) are experiencing abnormal wear, signaling a potential developing failure.
CMRT CMRT Lubrication and Tribology 2
Which contamination type is considered the number one destroyer of lubricated components in industrial machinery?