Calculate Specific Wear Rate and Volume Loss (Tribology)
Mass before test (grams)
Mass after test (grams)
Density in g/cm³ (e.g., Steel ~7.85)
Applied force in Newtons (N)
Total distance traveled in Meters (m)
Mass Loss (Δm):0 g
Volume Loss (V):0 mm³
Specific Wear Rate (k):0 mm³/N·m
Understanding Wear Rate and Tribology
The Wear Rate Calculator is an essential tool for materials engineers, tribologists, and mechanical designers. It quantifies the rate at which material is removed from a solid surface due to mechanical action, primarily friction between sliding surfaces. Understanding wear rate is critical for predicting the lifespan of components such as bearings, gears, seals, and prosthetics.
How to Calculate Specific Wear Rate
While simple wear can be expressed as mass loss or volume loss, the Specific Wear Rate (k) is the standard metric used to compare the wear resistance of different materials under varying loads. It normalizes the volume loss against the applied load and sliding distance.
k = V / (F × d)
Where:
k = Specific Wear Rate (mm³/N·m)
V = Wear Volume (mm³)
F = Normal Load (Newtons)
d = Sliding Distance (Meters)
Calculating Wear Volume from Mass
In most experimental setups (like Pin-on-Disk tests), wear is measured by weighing the specimen before and after the test. To use the specific wear rate formula, mass loss must first be converted to volume loss using the material's density.
V = (m1 – m2) / ρ × 1000
Here, the mass is in grams (g) and density is in g/cm³. The factor of 1000 converts the result from cm³ to mm³, which is the standard unit for wear volume in engineering contexts.
Common Material Densities
If you are unsure of your material's density, here are some common values (g/cm³):
Steel: 7.85
Aluminum: 2.70
Titanium: 4.50
Brass: 8.50
PTFE (Teflon): 2.20
Ceramic (Alumina): 3.95
Interpreting the Results
Lower values indicate better wear resistance. A specific wear rate in the range of 10-6 mm³/N·m or lower is typically considered good for engineering applications involving sliding contact. High wear rates (e.g., >10-3) suggest rapid material degradation and potential failure.
Archard's Wear Equation: The calculation performed here is derived from Archard's law, which states that the volume of material removed is proportional to the normal load and sliding distance, and inversely proportional to the hardness of the softer surface.
function calculateWearRate() {
// Clear previous errors
var errorDiv = document.getElementById("errorMessage");
var resultsDiv = document.getElementById("results");
errorDiv.style.display = "none";
resultsDiv.style.display = "none";
// Get Input Values
var initialMass = parseFloat(document.getElementById("initialMass").value);
var finalMass = parseFloat(document.getElementById("finalMass").value);
var density = parseFloat(document.getElementById("density").value);
var load = parseFloat(document.getElementById("normalLoad").value);
var distance = parseFloat(document.getElementById("slidingDistance").value);
// Validation Logic
if (isNaN(initialMass) || isNaN(finalMass) || isNaN(density) || isNaN(load) || isNaN(distance)) {
errorDiv.textContent = "Please fill in all fields with valid numbers.";
errorDiv.style.display = "block";
return;
}
if (density <= 0) {
errorDiv.textContent = "Density must be greater than zero.";
errorDiv.style.display = "block";
return;
}
if (load <= 0 || distance initialMass) {
errorDiv.textContent = "Final mass cannot be greater than initial mass (Mass gain is not wear).";
errorDiv.style.display = "block";
return;
}
// Calculations
// 1. Calculate Mass Loss (g)
var massLoss = initialMass – finalMass;
// 2. Calculate Volume Loss (mm^3)
// Density is g/cm^3.
// Mass is g.
// Volume (cm^3) = Mass / Density
// Volume (mm^3) = Volume (cm^3) * 1000
var volumeLoss = (massLoss / density) * 1000;
// 3. Calculate Specific Wear Rate (mm^3 / N.m)
// k = V / (F * d)
var wearRate = volumeLoss / (load * distance);
// Display Results
document.getElementById("resMassLoss").textContent = massLoss.toFixed(4) + " g";
document.getElementById("resVolumeLoss").textContent = volumeLoss.toFixed(4) + " mm³";
// Format Wear Rate (Scientific notation is better for very small numbers)
var formattedWearRate;
if (wearRate === 0) {
formattedWearRate = "0";
} else if (wearRate < 0.0001) {
formattedWearRate = wearRate.toExponential(4);
} else {
formattedWearRate = wearRate.toFixed(6);
}
document.getElementById("resWearRate").textContent = formattedWearRate + " mm³/N·m";
// Show Results Container
resultsDiv.style.display = "block";
}