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Guide
How to Estimate Machining Time
Accurate quoting is the difference between profit and loss. Learn the manual method to verify your CAM software.
Need a Quick Estimate?
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Total Time = Setup + (Cycle Time × Quantity)
Estimating a job isn't just about how long the tool is in the cut. It's about the entire door-open-to-door-open process.
1. Setup Time (Fixed)
- • Cleaning machine / Vise alignment
- • Tool setting / Touch off
- • First Article Inspection (FAI)
- • Program proofing
2. Cycle Time (Variable)
- • Cut Time: Tool actually removing metal
- • Non-Cut Time: Rapid moves, Tool changes
- • Load/Unload: Operator interaction
The 3-Step Estimation Process
1
Calculate "Time in Cut"
Determine the length of the tool path and divide by the feed rate.
Time (min) = Length of Cut (inches) / Feed Rate (IPM)
2
Add Non-Cutting Time
The "Hidden" costs. Machines aren't cutting 100% of the time.
- Tool Changes: Allow 5-10 seconds per tool.
- Rapid Moves: Add 10-20% to your cut time for air cutting.
- Spindle Ramping: 3-5 seconds to reach RPM.
3
Add Efficiency Factor
No operator runs at 100% efficiency all day.
The 80% Rule:
Divide your theoretical cycle time by 0.80 to account for fatigue, cleaning chips, bathroom breaks, and minor adjustments.
Real World Example: Aluminum Plate
Job: Face mill a 10" x 6" Aluminum plate.
Tool: 3" Face Mill, 5 Flutes.
| Parameter | Value |
|---|---|
| Cut Speed (IPM) | 150 IPM |
| Total Travel Length | 14 inches |
| Base Cut Time | 0.09 min |
| Non-Cut Time (Load/Unload/Rapids) | + 1.50 min |
| Total Estimated time | ~1.6 min |