function updateMillingLabels() {
var system = document.getElementById('unitSystem').value;
var adocLabel = document.getElementById('adocLabel');
var rdocLabel = document.getElementById('rdocLabel');
var feedLabel = document.getElementById('feedLabel');
var adocInput = document.getElementById('adoc');
var rdocInput = document.getElementById('rdoc');
var feedInput = document.getElementById('feedRate');
if (system === 'imperial') {
adocLabel.innerText = "Axial Depth of Cut (ADOC) [in]";
rdocLabel.innerText = "Radial Depth of Cut (RDOC/Width) [in]";
feedLabel.innerText = "Feed Rate [in/min – IPM]";
adocInput.placeholder = "e.g., 0.5";
rdocInput.placeholder = "e.g., 0.25";
feedInput.placeholder = "e.g., 40";
} else {
adocLabel.innerText = "Axial Depth of Cut (ADOC) [mm]";
rdocLabel.innerText = "Radial Depth of Cut (RDOC/Width) [mm]";
feedLabel.innerText = "Feed Rate [mm/min]";
adocInput.placeholder = "e.g., 12.7";
rdocInput.placeholder = "e.g., 6.35";
feedInput.placeholder = "e.g., 1000";
}
// Hide previous results to avoid confusion
document.getElementById('mrr-result').style.display = 'none';
}
function calculateMillingMRR() {
// Get Elements
var system = document.getElementById('unitSystem').value;
var adocInput = document.getElementById('adoc');
var rdocInput = document.getElementById('rdoc');
var feedInput = document.getElementById('feedRate');
var resultBox = document.getElementById('mrr-result');
var resultValue = document.getElementById('resultValue');
// Parse Values
var adoc = parseFloat(adocInput.value);
var rdoc = parseFloat(rdocInput.value);
var feed = parseFloat(feedInput.value);
// Validation
if (isNaN(adoc) || isNaN(rdoc) || isNaN(feed)) {
alert("Please enter valid numeric values for all fields.");
return;
}
if (adoc <= 0 || rdoc <= 0 || feed <= 0) {
alert("All values must be greater than zero.");
return;
}
var mrr = 0;
var unitLabel = "";
// Calculation Logic
if (system === 'imperial') {
// Formula: ADOC (in) * RDOC (in) * Feed (IPM)
mrr = adoc * rdoc * feed;
unitLabel = " in³/min";
} else {
// Formula Metric: (ADOC (mm) * RDOC (mm) * Feed (mm/min)) / 1000 = cm³/min
// Note: Standard metric MRR is often expressed in cm³/min for readability
mrr = (adoc * rdoc * feed) / 1000;
unitLabel = " cm³/min";
}
// Display Result
resultValue.innerText = mrr.toFixed(3) + unitLabel;
resultBox.style.display = 'block';
}
Understanding Material Removal Rate (MRR) in Milling
Material Removal Rate (MRR), often denoted as Q, is a critical efficiency metric in CNC machining and milling operations. It represents the volume of material removed from a workpiece per unit of time. Calculating MRR is essential for machinists and programmers who want to optimize cycle times, estimate machine power requirements, and maximize profitability without breaking tools.
The Milling MRR Formula
The calculation for MRR is straightforward, relying on three primary variables: the depth of the cut (both axial and radial) and the speed at which the tool moves across the workpiece.
ADOC (Axial Depth of Cut): The distance the tool engages the material along its centerline (Z-axis depth).
RDOC (Radial Depth of Cut): Also known as stepover or width of cut (WOC). This is the distance the tool engages the material perpendicular to its axis.
Feed Rate: The speed at which the cutting tool advances through the material, measured in Inches Per Minute (IPM) or Millimeters Per Minute (mm/min).
Why Calculate MRR?
Understanding your Material Removal Rate allows you to:
Compare Strategies: Determine if High-Speed Machining (HSM) with light cuts and high feeds is more efficient than traditional heavy roughing.
Estimate Power: Every cubic inch of material removed per minute requires a specific amount of horsepower depending on the material type (e.g., Aluminum vs. Steel). Knowing the MRR helps prevent stalling the spindle.
Quote Jobs Accurately: By knowing how fast you can remove rough stock, you can estimate machine run-time more precisely for customer quotes.
Example Calculation
Let's assume you are roughing a block of 6061 Aluminum using a 0.500″ End Mill with the following parameters:
Axial Depth (ADOC): 0.5 inches
Radial Depth (RDOC): 0.25 inches (50% stepover)
Feed Rate: 80 inches per minute (IPM)
Calculation: 0.5 × 0.25 × 80 = 10 in³/min.
This means you are turning 10 cubic inches of solid aluminum into chips every minute.
Optimizing for High Efficiency Milling (HEM)
Modern CAM software often utilizes High Efficiency Milling strategies (like VoluMill or Dynamic Milling). These strategies typically maintain a constant Tool Engagement Angle (TEA). In these scenarios, machinists often increase the ADOC significantly (using the full flute length) while decreasing the RDOC, but compensating with extremely high Feed Rates. This results in a massive MRR while reducing heat generation and extending tool life.