function calculateLinerWear() {
var originalDia = parseFloat(document.getElementById('cl_original_dia').value);
var currentDia = parseFloat(document.getElementById('cl_current_dia').value);
var hours = parseFloat(document.getElementById('cl_running_hours').value);
var limit = parseFloat(document.getElementById('cl_max_allowable').value);
var resultArea = document.getElementById('cl_result_area');
var totalWearDisplay = document.getElementById('cl_total_wear');
var wearRateDisplay = document.getElementById('cl_wear_rate');
var statusDisplay = document.getElementById('cl_status');
var lifeDisplay = document.getElementById('cl_projected_life');
// Validation
if (isNaN(originalDia) || isNaN(currentDia) || isNaN(hours) || hours <= 0) {
alert("Please enter valid numbers for Original Diameter, Current Diameter, and Running Hours.");
return;
}
// Logic
// Total Wear = Current – Original (Since wear increases bore size)
var totalWear = currentDia – originalDia;
// If user entered smaller current dia by mistake (implausible for bore wear), handle it
if (totalWear 0) {
if (wearRate > limit) {
statusDisplay.innerHTML = "CRITICAL (Exceeds Limit)";
statusDisplay.className = "cl-result-value cl-status-critical";
} else if (wearRate > (limit * 0.75)) {
statusDisplay.innerHTML = "WARNING (High Wear)";
statusDisplay.className = "cl-result-value cl-status-warning";
} else {
statusDisplay.innerHTML = "SAFE (Normal)";
statusDisplay.className = "cl-result-value cl-status-safe";
}
// Simple projection: If max total wear allowed is usually ~0.6-0.8% of bore,
// but let's assume specific max wear limit (e.g., 0.5% of diameter or fixed mm).
// Without a Max Total Wear Limit input, we can't accurately predict remaining life
// based on absolute diameter, so we will omit accurate projection or use a generic 0.8% threshold.
// Let's stick to rate-based status for accuracy.
lifeDisplay.innerHTML = "N/A (Requires Max Wear Limit)";
} else {
statusDisplay.innerHTML = "N/A (No Limit Set)";
statusDisplay.className = "cl-result-value";
lifeDisplay.innerHTML = "N/A";
}
}
Understanding Cylinder Liner Wear Rate
For marine engineers and heavy-duty engine mechanics, monitoring the condition of cylinder liners is critical for maintaining engine efficiency and preventing catastrophic failure. As an engine operates, the friction between the piston rings and the liner wall causes gradual material loss. This tool helps you calculate the Specific Wear Rate normalized to 1,000 running hours.
Why Calculate Liner Wear?
Cylinder liners are designed to wear down slowly over time. However, abnormal wear rates can indicate issues with:
Combustion: Cold corrosion due to low jacket water temperatures or high sulfur fuel.
Abrasives: Cat fines in fuel or dust intake.
By calculating the wear rate, you can predict when the liner will reach its condemning limit and schedule maintenance during dry docks or planned outages, rather than facing unexpected downtime.
The Wear Rate Formula
The standard industry calculation for specific cylinder liner wear is:
Current Diameter: The maximum measurement taken during calibration (usually in the thwartships direction at the top of ring travel).
Original Diameter: The manufacturer's nominal size or the baseline measurement taken when the liner was new.
Running Hours: The total number of hours the engine (and specifically that unit) has operated since the liner was installed.
Interpreting the Results
While every manufacturer (e.g., MAN B&W, Wartsila, Sulzer) has specific limits, general guidelines are:
0.02 – 0.05 mm/1000hrs: Excellent. Indicates good lubrication and optimal running conditions.
0.05 – 0.10 mm/1000hrs: Normal/Acceptable. Typical for older engines or those running on heavy fuel oil.
> 0.10 mm/1000hrs: High Wear. Investigation required into lubrication rates, fuel quality, or piston ring condition.
> 0.20 mm/1000hrs: Excessive. Critical action required to prevent liner cracking or blow-by.
How to Measure Correctly
To get accurate data for this calculator, ensure you use a precision inside micrometer. Measurements should be taken at various vertical positions (typically Positions 1 through 4/6) and in both Fore-Aft and Athwartships directions. The wear rate is usually calculated based on the position showing the maximum wear, which is typically at the top dead center (TDC) of the top piston ring, where combustion pressure and temperatures are highest.