What are the reasons for the large vibration of the hammer crusher?

Hammer crushers are widely used in mining, cement, metallurgy, and aggregate industries for crushing medium-hard materials such as limestone, coal, and gypsum. However, abnormal vibration during operation is a common issue that can severely impact machine performance and lifespan.Large vibrations in a hammer crusher are a common problem and can lead to premature wear, component failure, reduced efficiency, and safety hazards. 

Reasons for Large Vibration of Hammer Crusher

Rotor Imbalance (Most Common Cause):

Uneven Hammer Wear: Hammers wear down at different rates depending on their position and the feed material. If not managed, this creates a significant weight imbalance.

Incorrect Hammer Replacement: Replacing hammers with ones of different weights, or replacing only some hammers without balancing, will cause imbalance.

Hammers should always be replaced in sets (opposite pairs or full sets) and be weight-matched.

Broken or Missing Hammers/Pins: A broken hammer or a lost hammer pin will immediately create a severe imbalance.

Material Buildup: Sticky or wet material can build up unevenly on the rotor, hammers, or inside the rotor discs, adding weight to one side.

Bent Rotor Shaft: A bent shaft will cause the entire rotor assembly to wobble.

Rotor Disc Deformation: If the discs holding the hammers are bent or damaged.

Bearing Issues:

Worn or Damaged Bearings: Worn bearings develop excessive clearance (play), allowing the shaft to move erratically, leading to vibration. Damaged races or rolling elements also cause rough running.

Incorrect Bearing Lubrication: Too little, too much, or the wrong type of lubricant can cause bearings to overheat and fail.

Misaligned Bearing Housings: If the bearing housings are not perfectly aligned, they put undue stress on the bearings and shaft.

Loose Components:

Loose Foundation Bolts: If the crusher is not securely anchored to its foundation, it will vibrate excessively.

Loose Rotor Mounting Bolts: Bolts connecting the rotor to the shaft or bearing assemblies.

Loose Hammer Pins/Bolts: If hammer pins are loose, hammers can shift, contributing to imbalance and impact forces.

Loose Liner Plates or Grate Bars: Can vibrate independently or cause material to jam.

Operational Issues:

Overfeeding: Feeding too much material at once can choke the crusher, leading to uneven loads and vibration.

Feeding Uncrushable Material: Introducing tramp metal or excessively hard material can cause sudden shocks and damage, leading to vibrations.

Uneven Feed Distribution: If material is consistently fed to one side of the crusher, it will cause uneven wear on hammers and liners, eventually leading to imbalance.

Incorrect Rotor Speed: Operating outside the designed speed range can cause issues, sometimes hitting a resonant frequency.

Structural and Installation Issues:

Weak or Damaged Foundation: A foundation that is not rigid enough or is cracked cannot adequately absorb the machine's operational vibrations, amplifying them.

Misalignment: Misalignment between the motor and the crusher shaft (if directly coupled or via couplings) can induce vibration.

Resonance: The operating frequency of the crusher might coincide with the natural frequency of the support structure or nearby equipment, leading to amplified vibrations.

Other Mechanical Issues:

Bent or Damaged Shaft: As mentioned with rotor imbalance, but can also be a standalone issue.

Worn or Damaged Couplings (if used): Can transmit vibrations or fail to dampen them.

Cracks in the Crusher Body or Rotor: Can compromise structural integrity and lead to unstable operation.

Addressing large vibrations promptly is crucial. It usually involves a systematic inspection, starting with the most common causes like rotor balance and loose components.