Material Removal Rate
Calculate MRR (Cubic Inches per Minute) to quantify machining efficiency and estimate spindle horsepower requirements.
Why MRR Matters
MRR is the ultimate metric for roughing operations. While speeds and feeds optimize tool life, MRR dictates how fast you are actually making a part.
The Horsepower Limit
A common error is programming aggressive roughing toolpaths that calculate perfectly for chipload, but exceed the spindle's available horsepower, resulting in spindle stalls or destroyed tooling.
The "Unit Power" required to remove 1 cubic inch of material per minute varies by material hardness and machinability. While Aluminum requires roughly 0.25 to 0.3 HP per in³/min, tough alloys like Titanium or Inconel can require 1.2 to 1.5 HP.
High-Efficiency Milling (HEM) vs Traditional
| Strategy | DOC | WOC | Feed |
|---|---|---|---|
| Traditional | Small (< 1xD) | Large (50%+) | Slower |
| HEM / Trochoidal | Large (up to 3xD) | Small (5-15%) | Very Fast |
Note: HEM strategies often yield lower raw MRR than brute-force traditional roughing, but achieve longer tool life and require less peak horsepower.