What is blow bar indexing?
Blow bar indexing means rotating each blow bar in an HSI crusher to expose a fresh, unworn edge before the current edge wears out completely. This single action can double total wear life without buying new bars.
Why does indexing matter for your production cost?
One set of blow bars typically costs $2,000–$8,000.
Without indexing, you use only 50% or less of the available wear material.
With proper indexing, you use nearly 100% of every bar.
Result: wear cost per ton drops by almost half.
When should you rotate blow bars? (The 30% rule)
Rotate when wear depth reaches 25–30% of the original bar thickness.
Too early → you lose some potential life.
Too late (>40% wear) → risk of bar cracking, rotor imbalance, and poor product shape.
Quick field check: Paint a white stripe on the working face. When the stripe disappears, index immediately.
Recommended indexing intervals by rock type
| Rock Abrasivity | Example Materials | Indexing Interval (crushing hours) |
|---|---|---|
| High | Granite, basalt, river gravel | 120–180 hours |
| Medium | Hard limestone, diabase | 200–300 hours |
| Low | Soft limestone, recycled concrete | 350–500 hours |
Step‑by‑step correct indexing procedure
Stop the crusher and lock out power.
Remove all blow bars – never index one bar alone.
Clean rotor pockets – debris prevents proper seating.
Rotate each bar to the next fresh face (180° or 90° as per bar design).
Check retaining wedges or bolts – torque to manufacturer specification.
Record the rotation in a log: date, hours on previous face, observed wear pattern.
What happens if you don’t index all bars together?
Uneven wear across bars creates rotor vibration, bearing stress, and irregular product gradation. One worn bar compromises the whole set.
Quick reference for operators
Index when wear reaches 30% of bar thickness.
Always rotate all bars together.
Granite/basalt: rotate every 150 hours.
Limestone: rotate every 400 hours.
Paint stripe check is the simplest method.
Following this schedule doubles wear life.
