мельница Raymond (also known as Raymond roller mill) is widely used in grinding non-flammable and non-explosive materials with Mohs hardness below 7 and humidity below 6%, such as limestone, calcite, barite, dolomite, and gypsum. However, during prolonged operation, various issues may arise that affect production efficiency and product quality. This article outlines the most frequent problems encountered and offers practical maintenance advice.

1. Low Output or Blockage

Symptoms: Reduced production rate, material buildup inside the mill, and frequent shutdowns.

Possible causes:

• Excessive feeding rate exceeding the mill’s capacity
• High moisture content in raw material (above 6%) causing internal sticking
• Worn grinding rollers or grinding rings
• Blocked air duct or collector filter

Maintenance solutions:

• Adjust the feeder to ensure uniform and controlled feed rate
• Pre-dry materials with high moisture content
• Inspect and replace worn rollers or rings regularly
• Clean the air passage and pulse dust collector filter bags

2. Abnormal Vibration or Loud Noise

Symptoms: The mill body shakes noticeably, accompanied by knocking or grinding sounds.

Possible causes:

• Uneven or excessive feed causing imbalance
• Loose anchor bolts or foundation
• Damaged or unbalanced grinding rollers
• Foreign objects (e.g., metal fragments) entering the grinding chamber

Maintenance solutions:

• Stop the mill immediately and remove foreign matter
• Tighten all foundation and flange bolts
• Replace damaged rollers or repair balance
• Ensure feed material is free of impurities using a magnetic separator

3. Overheating of Bearings

Symptoms: Bearing housing temperature exceeds 70°C, oil smoke or discoloration appears.

Possible causes:

• Insufficient or contaminated lubricating oil
• Excessive bearing clearance or preload
• Long-term overload operation

Maintenance solutions:

• Change lubricating oil every 1–3 months (use recommended grease or oil type)
• Clean bearings and refill to proper oil level
• Adjust bearing clearance or replace worn bearings
• Reduce feed load and allow the mill to cool down during extended runs

4. Unstable Product Fineness

Symptoms: The ground powder is too coarse or contains oversized particles.

Possible causes:

• Worn classifier blades or incorrect classifier rotor speed
• Leaking seal between grinding chamber and classifier
• Low air volume or negative pressure drop

Maintenance solutions:

• Adjust the classifier speed; replace worn blades
• Check and replace sealing gaskets
• Inspect the fan and air ducts for leaks; clean the outlet pipe

5. Grinding Rollers and Rings Wear Rapidly

Symptoms: Frequent replacement of rollers/rings, decreased grinding efficiency.

Possible causes:

• Grinding hard or abrasive materials (e.g., quartz, iron ore)
• Improper roller pressure setting
• Insufficient lubrication of roller bearings

Maintenance solutions:

• Use materials within the mill’s specified hardness range (≤7 Mohs)
• Reduce grinding pressure appropriately
• Lubricate roller bearings every 500 hours of operation
• Replace worn parts in pairs (both rollers or both rings) to maintain balance

6. Frequent Tripping of Motor Overload Protection

Symptoms: Circuit breaker trips repeatedly during operation.

Possible causes:

• Overload due to excessive feed or internal blockage
• Low voltage supply or motor phase loss
• Mechanical resistance (e.g., stuck grinding rollers)

Maintenance solutions:

• Reduce feed rate and clear any blockage
• Check power supply stability and motor wiring
• Manually rotate the main shaft to feel for binding; disassemble and inspect if necessary

Preventive Maintenance Checklist

To minimize downtime and extend the life of your Raymond mill, follow these routine practices:

Safety Reminder

Always shut down the mill and disconnect power before performing any repair or cleaning. Lockout/tagout procedures should be strictly followed. Wear appropriate personal protective equipment (PPE), including gloves, goggles, and dust masks.

By promptly identifying these common issues and adhering to a regular maintenance schedule, operators can keep Raymond mills running reliably, reduce unexpected breakdowns, and ensure consistent product quality.