what grease should we use in the cone crusher

The Definitive Guide to Cone Crusher Lubrication: Selecting the Right Grease for Maximum Uptime and Performance

In the demanding world of aggregate and mining operations, the cone crusher stands as a critical piece of equipment, responsible for reducing large rocks into precisely sized aggregate. Its relentless work generates immense mechanical forces, shock loads, and significant heat. While hydraulic oil lubricates the internal clamping and adjustment systems, it is the grease in the bearings—particularly the eccentric and step bearings—that forms the first line of defense against friction and wear. The selection of the correct grease is not a matter of convenience; it is a fundamental decision that directly impacts machine reliability, maintenance costs, and overall operational profitability.

1. Understanding the Hostile Environment Inside a Cone Crusher

To select the right grease, one must first appreciate the extreme conditions it must endure:

Heavy Loads: Eccentric bearings support tremendous radial and axial loads as the mantle gyrates against the concave.
Shock Loads: Uncrushable material (tramp metal) can cause sudden, severe shock loads that threaten to break down the lubricating film.
Contamination: Dust, dirt, and fine particulate matter are omnipresent in crushing plants. An effective grease must have excellent sealing properties to exclude these contaminants.
Water Washout: In some operations, water is used for dust suppression. Grease must resist being washed out of bearings by moisture.
High Temperatures: Friction from crushing and ambient heat can cause bearing temperatures to rise significantly.

A standard multi-purpose grease is simply not engineered to withstand this combination of challenges for extended periods.

2. The Core Characteristics of High-Performance Crusher Grease

The ideal cone crusher grease is a high-performance, semi-fluid or solid grease specifically formulated with several non-negotiable attributes:

A. Thickener Type: Lithium Complex or Polyurea
Lithium Complex: This is the most common and versatile thickener for severe-duty applications. It offers excellent mechanical stability (resistance to breakdown from shearing), high-temperature resistance (typically up to 350°F / 177°C), and good water resistance.
Polyurea: Known for exceptional oxidation stability, which translates to a longer service life at high temperatures. It also provides excellent corrosion protection and is inherently tacky, helping it stay in place. Some formulations can be less compatible with other thickeners.

B. Base Oil Viscosity: The Foundation of Lubrication
The base oil used in the grease must have a high viscosity index. A thicker oil film is essential to separate metal surfaces under extreme pressure and shock loading. A typical ISO Viscosity Grade (VG) for crusher greases ranges from VG 150 to VG 460. The specific recommendation should always align with the OEM's guidelines based on bearing size and operating speed.

C. Extreme Pressure (EP) and Anti-Wear (AW) Additives
These are critical additives that prevent metal-to-metal contact during boundary lubrication conditions (start-up, shock loads). They form a protective sacrificial layer on metal surfaces.
EP Additives: Typically contain Sulfur-Phosphorus compounds that react with metal surfaces under high pressure to form a protective film.
AW Additives: Such as Zinc Dialkyldithiophosphate (ZDDP), provide protection under lower loads but are still essential for overall wear reduction.

D. Solid Lubricants: The "Insurance Policy"
Many premium crusher greases include solid lubricants like Molybdenum Disulfide (Moly) or Graphite. These particles provide an additional layer of lubrication that remains effective even if the primary oil film is temporarily squeezed out during an extreme shock load.

E. Tackiness Agents
These additives give the grease a stringy, adhesive quality, preventing it from being thrown off or centrifuged out of high-speed bearings.

3. Application Protocol: How Much and How Often?

Using the correct grease incorrectly will still lead to failure.

Purge Schedule: The primary method of greasing eccentric bearings on most cone crushers is through an automated lubrication system that injects a metered amount at regular intervals.
Too little grease leads to bearing starvation and overheating.
Too much grease can cause churning, leading to excessive heat buildup and potential seal damage.
Follow OEM recommendations precisely for purge volume and frequency (e.g., every 15-30 minutes for 5-10 seconds). Adjustments may be needed based on ambient temperature and crusher load.

Manual Re-lubrication: For other points like countershaft bearings or bushings, manual greasing should be performed during scheduled maintenance shutdowns until clean grease is seen purging from the seal—this ensures old, contaminated grease is expelled.

4. Common Pitfalls & Best Practices

1. Mixing Greases: Never mix different thickener types (e.g., Lithium Complex with Polyurea). Incompatible greases can react, causing oil separation or a complete loss of consistency, leading to lubrication failure.
2. Over-greasing: This is as dangerous as under-greasing. It creates heat and can blow out critical seals.
3. Ignoring Purged Grease: The condition of the grease purging from seals is a vital diagnostic tool. If it contains metal particles ("butcher's glitter"), it indicates active wear inside.
4. Storage: Store grease in a clean, dry place. Keep drums covered and use dedicated, clean grease guns to prevent contamination.

5.Frequently Asked Questions (FAQ)

Q1: Can I use a standard automotive lithium-based grease in my cone crusher?
A: Absolutely not. Automotive greases are not designed for continuous extreme pressure, shock loading, or contamination resistance required by an industrial cone crusher. Using them will drastically shorten bearing life.

Q2: My OEM manual specifies one brand; do I have to use that exact brand?
A: Not necessarily; however you must match or exceed its performance specifications (thickener type base oil viscosity EP/AW performance). Using an OEM-approved equivalent from another reputable lubricant supplier is common practice but requires careful technical cross-referencing

Q3: How do I know if I'm using too much or too little grease?
A:
Signs of Under-greasing: High bearing temperature noise increase visible wear on purged grease
Signs of Over-greasing: High bearing temperature especially immediately after a purge cycle;grease leaking excessively from seals

Q4: What should I do if my crusher has been exposed to flooding or significant water ingress?
A: This constitutes an emergency situation Flush bearings immediately with a light viscosity rust-preventive oil followed by several complete re-lubrications with fresh water-resistant grease Water will quickly degrade both base oil additives leading rapid corrosion failure

Engineering Case Study

Scenario A granite quarry was experiencing premature failures eccentric bearing sets their large secondary cone crusher every ~ months despite following recommended purge intervals

Investigation Analysis used purged sample revealed standard multi-purpose lithium EP grease being applied Bearing teardown showed classic fatigue pitting signs inadequate lubrication film under load

Solution Operation switched true lithium complex-based crusher-specific with ISO VG high Moly content adjusted purge frequency based thermal imaging monitoring

Result Bearing life extended months representing % improvement reduced unplanned downtime annual savings exceeding $ in parts labor alone

Conclusion
Selecting proper cone isn't about buying expensive tube It requires systematic understanding machine’s operating environment rigorous evaluation product’s technical attributes disciplined application protocol Treating lubrication critical component system itself rather than ancillary task single most effective strategy maximizing asset availability protecting your bottom line