מחשבון איזון טחנת פטיש

Unbalanced hammer mills cause:

• Excessive vibration — grows with the square of RPM, leading to structural damage
• Premature bearing failure — bearing life drops with the cube of excess force
• Foundation damage — dynamic forces transmitted to concrete and steel structure
• Safety hazards — risk of catastrophic failure and thrown components
• Inconsistent product — uneven grinding and throughput

Proper hammer arrangement is the first and cheapest step toward smooth operation.

A mass difference of just 1 kg on a rotor with R = 400 mm at 1500 RPM creates a centrifugal unbalance force of ~9.9 kN (1 tonne-force). This force rotates with the rotor, causing:

• 1× RPM vibration component
• Accelerated bearing wear
• Bolt loosening and fatigue cracking
• Noise and operator discomfort

The force increases with RPM², so doubling the speed quadruples the force.

Best practices:

• Weigh every hammer before installation (to 1g for hammers under 10 kg)
• Match opposing positions — for 4-position rotors, match pairs (1+3) and (2+4)
• Equal total mass per position — redistribute to minimize difference
• Record weights — keep a logbook of hammer masses and positions
• Replace in sets — when replacing worn hammers, replace all on a position pair

A systematic rotation pattern maximizes hammer life and maintains balance:

1. Step 1: Flip all hammers 180° (use the unworn cutting edge)
2. Step 2: Swap inner and outer disc positions
3. Step 3: Move between opposing circumferential positions

This creates a 6-stage rotation cycle before replacement. At each rotation:

• Weigh all hammers
• Group by weight for matching
• Discard any below minimum weight
• Document in maintenance log

Recommended tolerances:

• Individual hammer matching: ±1–2% between opposing hammers
• Position total mass: <2% difference of total hammer mass
• Vector unbalance: <1% of total mass = good, 1–2% = acceptable, >2% = redistribute

Use a scale with resolution of at least 1g for hammers under 10 kg, or 10g for heavier hammers.