🎓 Lesson 8
D5
Drill Rig Productivity KPIs Explained
Drill rig productivity KPIs are simple numbers—like how many meters you drill per hour—that tell you if your drilling operation is fast, efficient, and cost-effective.
🎯 Learning Objectives
- ✓ Calculate penetration rate (m/hr) and advance rate (m/hr) from field log data
- ✓ Analyze rig utilization percentage using scheduled vs. productive time records
- ✓ Explain the relationship between bit wear (measured in meters drilled per bit) and rock abrasivity (using Protodyakonov coefficient)
- ✓ Apply cost-per-meter KPI to compare economic performance across two drill rig types under identical ground conditions
📖 Why This Matters
In open-pit mines, drilling accounts for 15–25% of total blast-related costs—and poor drill productivity cascades into suboptimal fragmentation, increased secondary breaking, and higher overall excavation costs. A 10% gain in effective drill advance rate can reduce annual drilling costs by over $1.2M in a mid-size copper mine. Understanding these KPIs isn’t just about measuring speed—it’s about linking machine performance to blast quality, safety, and profitability.
📘 Core Principles
Drill rig productivity is governed by three interdependent domains: mechanical (rig power, bit type, rotation/impact energy), geological (rock strength, abrasivity, jointing), and operational (shift planning, maintenance discipline, crew training). Penetration rate reflects instantaneous bit-rock interaction; advance rate includes non-drilling time (e.g., rod handling, surveying, repositioning); utilization captures calendar-time efficiency. Critically, high penetration does not guarantee high advance—poor housekeeping or unplanned downtime erodes gains. Industry best practice distinguishes 'drilling time' (bit-on-rock) from 'productive time' (includes positioning and setup), both tracked separately in modern fleet management systems (FMS).
📐 Penetration Rate & Advance Rate
Penetration rate measures raw drilling speed; advance rate reflects real-world progress. Both are foundational for estimating cycle times and fleet sizing. Advance rate is always ≤ penetration rate due to auxiliary tasks.
💡 Worked Example
Problem: A D65-30 hydraulic top-hammer rig drills a 152-mm hole in porphyritic granite (UCS ≈ 180 MPa). Field logs show: 42 minutes of bit-on-rock time, 78 minutes total cycle time (including rod changes, surveying, and repositioning), and 12.6 m advanced.
1.
Step 1: Convert bit-on-rock time to hours: 42 min = 0.7 hr → Penetration rate = 12.6 m / 0.7 hr = 18.0 m/hr
2.
Step 2: Convert total cycle time to hours: 78 min = 1.3 hr → Advance rate = 12.6 m / 1.3 hr = 9.7 m/hr
3.
Step 3: Utilization = (0.7 hr / 1.3 hr) × 100% = 53.8% — below the target of ≥65% for this rig class per SME Best Practices (2022)
Answer:
Penetration rate = 18.0 m/hr; Advance rate = 9.7 m/hr; Utilization = 53.8%. The low utilization signals opportunity for procedural optimization—not necessarily rig replacement.
🏗️ Real-World Application
At Newmont’s Boddington Mine (Western Australia), a shift from DTH to rotary-percussion rigs on saprolite overburden increased average advance rate from 6.2 to 11.4 m/hr—yet fragmentation suffered due to reduced energy coupling. Engineers responded by integrating KPI tracking with blast design software (SHOVEL™), adjusting burden and spacing based on measured advance rates and actual powder factor. This closed-the-loop approach improved throw control by 18% and reduced oversize by 23%, proving that KPIs must be interpreted contextually—not in isolation.
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