.mrr-calculator-container {
max-width: 600px;
margin: 20px auto;
padding: 25px;
background-color: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
font-family: Arial, sans-serif;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.mrr-header {
text-align: center;
margin-bottom: 25px;
color: #333;
}
.mrr-form-group {
margin-bottom: 20px;
}
.mrr-form-group label {
display: block;
margin-bottom: 8px;
font-weight: bold;
color: #444;
}
.mrr-input-wrapper {
display: flex;
align-items: center;
}
.mrr-form-group input[type="number"] {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
}
.mrr-unit-toggle {
display: flex;
justify-content: center;
gap: 20px;
margin-bottom: 20px;
padding-bottom: 15px;
border-bottom: 1px solid #eee;
}
.mrr-unit-label {
font-weight: normal;
cursor: pointer;
display: flex;
align-items: center;
gap: 5px;
}
.mrr-btn {
width: 100%;
padding: 12px;
background-color: #0056b3;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
cursor: pointer;
transition: background-color 0.2s;
}
.mrr-btn:hover {
background-color: #004494;
}
.mrr-result {
margin-top: 25px;
padding: 20px;
background-color: #e8f4fd;
border: 1px solid #b6e0ff;
border-radius: 4px;
text-align: center;
display: none;
}
.mrr-result h3 {
margin: 0 0 10px 0;
color: #0056b3;
font-size: 24px;
}
.mrr-result p {
margin: 0;
color: #555;
}
.input-hint {
font-size: 12px;
color: #666;
margin-top: 5px;
}
/* Article Styles */
.mrr-article {
max-width: 800px;
margin: 40px auto;
font-family: Arial, sans-serif;
line-height: 1.6;
color: #333;
}
.mrr-article h2 {
color: #2c3e50;
border-bottom: 2px solid #0056b3;
padding-bottom: 10px;
margin-top: 30px;
}
.mrr-article h3 {
color: #2c3e50;
margin-top: 25px;
}
.mrr-article ul {
margin-bottom: 20px;
}
.mrr-article li {
margin-bottom: 10px;
}
.formula-box {
background: #f4f4f4;
padding: 15px;
border-left: 4px solid #0056b3;
font-family: "Courier New", monospace;
margin: 20px 0;
}
function updateLabels() {
var isMetric = document.getElementById('unitMetric').checked;
if (isMetric) {
document.getElementById('labelSpeed').textContent = "Cutting Speed (Vc) [m/min]";
document.getElementById('labelFeed').textContent = "Feed per Revolution (fn) [mm/rev]";
document.getElementById('labelDepth').textContent = "Depth of Cut (ap) [mm]";
document.getElementById('cuttingSpeed').placeholder = "e.g. 150";
document.getElementById('feedRate').placeholder = "e.g. 0.25";
document.getElementById('cutDepth').placeholder = "e.g. 2.0";
} else {
document.getElementById('labelSpeed').textContent = "Cutting Speed (Vc) [SFM]";
document.getElementById('labelFeed').textContent = "Feed per Revolution (fn) [in/rev]";
document.getElementById('labelDepth').textContent = "Depth of Cut (ap) [inch]";
document.getElementById('cuttingSpeed').placeholder = "e.g. 500";
document.getElementById('feedRate').placeholder = "e.g. 0.010";
document.getElementById('cutDepth').placeholder = "e.g. 0.100";
}
// Hide result when units change to avoid confusion
document.getElementById('mrrResult').style.display = 'none';
}
function calculateMRR() {
// Get Inputs
var vc = parseFloat(document.getElementById('cuttingSpeed').value);
var fn = parseFloat(document.getElementById('feedRate').value);
var ap = parseFloat(document.getElementById('cutDepth').value);
var isMetric = document.getElementById('unitMetric').checked;
var resultDisplay = document.getElementById('mrrResult');
var resultValue = document.getElementById('mrrValue');
var resultUnit = document.getElementById('mrrUnit');
// Validation
if (isNaN(vc) || isNaN(fn) || isNaN(ap) || vc <= 0 || fn <= 0 || ap <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
var mrr = 0;
// Calculation Logic
if (isMetric) {
// Metric Calculation
// Formula: Q = Vc * fn * ap
// Vc is in m/min, we convert to cm/min for the result usually, or keep consistent units.
// Standard Metric MRR is cm³/min.
// 1 m = 100 cm. 1 mm = 0.1 cm.
// Q (cm³/min) = (Vc * 100) * (fn / 10) * (ap / 10)
// Q = Vc * fn * ap * (100 * 0.1 * 0.1)
// Q = Vc * fn * ap * 1
// So numerically, m/min * mm/rev * mm = cm³/min
mrr = vc * fn * ap;
resultUnit.textContent = "cm³/min";
} else {
// Imperial Calculation
// Formula: Q = 12 * Vc * fn * ap
// Vc is Surface Feet per Minute (SFM)
// fn is Inch per Revolution (IPR)
// ap is Inch
// Result is cubic inches per minute (in³/min)
mrr = 12 * vc * fn * ap;
resultUnit.textContent = "in³/min";
}
// Display Result
resultValue.textContent = mrr.toFixed(2);
resultDisplay.style.display = 'block';
}
Understanding Material Removal Rate (MRR) in Turning
In CNC turning and manual lathe operations, the Material Removal Rate (MRR) is a critical metric that defines how much material volume is removed from a workpiece per unit of time. It is a direct indicator of machining efficiency and is essential for calculating power requirements and cycle times.
The Logic Behind the Calculation
MRR represents the volume of the "chip" being formed continuously as the tool engages the workpiece. For turning operations, this is calculated using three primary variables: Cutting Speed, Feed Rate, and Depth of Cut.
Metric Formula (Q):
Q = Vc × fn × ap
Where result is in cm³/min
Imperial Formula (Q):
Q = 12 × Vc × fn × ap
Where result is in in³/min
Input Definitions
- Cutting Speed (Vc): The speed at which the workpiece surface moves past the cutting tool edge.
- Metric: Meters per minute (m/min).
- Imperial: Surface Feet per Minute (SFM).
- Feed per Revolution (fn): The distance the cutting tool travels axially along the workpiece for one complete revolution of the spindle.
- Metric: Millimeters per revolution (mm/rev).
- Imperial: Inches per revolution (IPR).
- Depth of Cut (ap): The perpendicular distance from the uncut surface to the cut surface (radial depth).
- Metric: Millimeters (mm).
- Imperial: Inches (in).
Why MRR Matters
1. Efficiency Optimization: A higher MRR means you are removing material faster, reducing cycle time. However, this must be balanced against tool life and surface finish requirements.
2. Power Calculation: The main spindle motor has a limited power output. You can estimate the required power ($P_c$) by multiplying the MRR by the specific cutting force ($k_c$) of the material. If your calculated MRR requires more horsepower than your machine has, the spindle may stall.
3. Tool Life Management: While maximizing MRR increases productivity, pushing parameters too high (especially cutting speed) generates excessive heat, which degrades carbide inserts rapidly.
Example Calculation
Let's assume you are turning a steel shaft using Imperial units:
- Cutting Speed: 600 SFM
- Feed Rate: 0.012 IPR
- Depth of Cut: 0.150 inches
Using the formula: $Q = 12 \times 600 \times 0.012 \times 0.150$
Result: $12.96 \text{ in}^3/\text{min}$.
This means nearly 13 cubic inches of steel are turned into chips every minute.