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Mining Ask The Expert: How to boost crusher uptime by improving shock-load, pressure and vibration protection Daniel Narnhammer discusses the importance of using specialty lubricants in mineral processing equipment.

In this interview, Daniel Narnhammer discusses the importance of using specialty lubricants in mineral processing equipment.

Q: Can lubricants really improve crusher uptime?

A: The heart of a crusher are the roller bearings, thrust bearings and spider cap bushings. Whether it’s a jaw, gyratory or hammer crusher, the bearings must cope with varying loads, shock loads, elevated temperatures, high vibrations, or even contamination with minerals. Greases with high base oil viscosities and additive packages protect those components from shock loads, high Hertzian pressure and high vibrations.

Q: Do you prove the benefits of using advanced lubricants?

A: Our products undergo intense lab and tribology testing. For example, our greases and oils for heavy mineral processing equipment are all tested on the FAG FE-8 test rig. This test proves the bearing protection performance of a grease or oil. Our lubricants are also tested for seal compatibility.

Q: What kinds of lubricants are used in crushers?

A: Two types of lubricants are used, either oil lubrication or grease lubrication. Both types have their advantages and disadvantages.

Q: What are the advantages of using advanced oils?

A: High-performance specialty oils help clean sealed systems. There are no lost lubricants, because the oil circulates within the system. Also, it helps cooling components by transferring heat away from moving parts. On the other hand, if the system is contaminated, the particles circulate in the oil. With an oil circulation system, maintenance is higher due to filter changes, leakage prevention, etc. The complex design of circulation systems may also be a source of failure. Bearing seals are also subject to failures

Q: What about greases?

A: With greases, there is a so-called “lost lubrication” function that constantly cleans the bearings by purging contamination. The grease also acts like a seal and keeps contamination out. Grease provides good protection against shock load. Plus, the lubrication system is simple, it just involves a drum pump, pipes and injectors. On the other hand, grease consumption can be higher. In cold climates, a drum heater may be needed to make certain greases pumpable. Finally, good greases are rare. It takes special technology to develop and produce such advanced products.

Q: What lubricant products work for crushers?

A: For oils, high-performance Klübersynth GEM 4 synthetic gear oils based on polyalphaolefin outperform typical mineral oils and other synthetic gear oils. For greases, we have a large variety, but these three are our most important ones: Klüberlub BE 41-1501, Klüberlub BE 41-1002, Klüberplex EM 91-152.

Q: What are the specific benefits of these products?

A: It depends on the formulation. Compared to competitive greases, Klüberlub BE 41-1501 offers a 50 percent higher base oil viscosity over competitor products, which creates a sufficient lubrication film thickness and reduces vibrations. Greases containing solid lubricants in a balanced combination prevent fretting and ensure good emergency lubrication if the oil film breaks down or the lube system fails. These formulations use state-of-the-art solid lubricants with extreme small particle sizes. Other benefits include:

  • Advanced EP (Extreme Pressure) additives to withstand high Hertzian pressures.
  • Synthetic base oils ensure pumpability and low start-up torque at colder ambient temperatures.
  • Excellent tackiness and water resistance to avoid water washout.
  • Compatibility with different types of alloy materials.

Our high-performance oils exhibit also employ advanced EP additives to withstand high Hertzian pressures. All our oils are bearing tested and have an additive package to address specific bearing needs

Q: How important is choosing the proper lubricant for crusher operators?

A: It is extremely important. Oils and greases must provide the best component protection possible. That’s why lubricant manufacturers design their products specifically for the needs of heavy mineral processing equipment.

Q: What happens if the crusher is not properly lubricated?

A: It can have a huge impact on production downtime. Operators cannot afford to risk a breakdown or bearing replacement due to an incorrect lubricant purchased based on price alone. Inferior lubricants cannot protect the bearings, aren’t pumpable at lower temperatures, do not generate the sufficient film thickness in the bearing and thus cause high wear, energy losses or event component failures.

Q: Can you put a number on typical lubricant life in crusher applications? Does it depend on the crusher type as well as the operating conditions?

A: With grease lubrication, there is no lifetime, because “by design” it’s lost lubrication. The grease stays in the bearing only for a short time period. But here are some numbers for oils:

  • Mineral oil lifetime: Up to 1.5 years
  • PAO (Poly-alpha-olefin) based synthetic base oil lifetime: From 2-3 years
  • Polyglycol based synthetic base oil lifetime: Up to 5 years

All of the above depends on the contamination degree, the maintenance of the lubrication system, as well as the actual operating hours and operating temperature.

Q: Can regular fine filtration help to extend fluid lubricant life?

A: A clear “yes” only for oil lubricated bearings. But filtration must be done continuously with the correct filter. The filter type (filter pore size) must be chosen correctly in consideration of the maximum achievable lubricant film thickness and the possible contamination type (i.e., which minerals are being processed).

Q: As a lubricant manufacturer, what kind of crusher maintenance problems do you see?

A: We see a variety of issues in the field, such as incorrect bearing greases being used and end-users not following OEM recommendations. For example, mines use standard EP-1 or EP-2 products for large bearings and extreme loads. These greases have neither the sufficient base oil viscosity nor the right additives. It’s like running a race car with 87 octanes and aiming for the F1 championship.

Improper re-lubrication practices with greases can be: long re-lubrication intervals, over lubrication and mixing of incompatible greases or oils.

Another frequent issue is suboptimal maintenance of the lubrication systems, e.g., oil filters aren’t changed frequently, failed grease injector nozzles or failed drum pumps.

Finally, there’s usually a need to give maintenance personnel sufficient training on lubrication best practices. For example, installing an incompatible lube/seal combination can result in failed seals that cause high contamination.

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