Views: 109 Author: DR.LIU XIANG Publish Time: 2026-04-21 Origin: Site
The filter screen of a laser chiller must be cleaned every 7–30 days, depending on ambient dust levels, and the distilled water must be replaced every 3–6 months. A clogged filter screen reduces coolant flow, causing the chiller to alarm (water pressure drop >0.5 bar) and the laser source to overheat. Water that has not been replaced accumulates ions (conductivity >50 µS/cm), which can corrode the laser diode cooling plates and cause electrical leakage. The correct procedure is: power off the chiller, remove and rinse the filter screen with clean water (or replace if damaged), flush the cooling circuit with fresh distilled water, then refill with deionized water mixed with a corrosion inhibitor (e.g., 30% ethylene glycol for freezing conditions). Failure to maintain the chiller voids the laser warranty.
Your laser cutter suddenly alarms with a “Chiller” error. The laser power drops by 30%. The cutting edge becomes rough. You check the chiller display: water temperature is 32°C (setpoint 25°C), pressure is 2.5 bar (normal is 4.0 bar). The filter screen is covered with black slime and metal particles. The water is brownish and smells musty. The chiller has not been serviced in 8 months.
The cooling system is the lifeblood of a fiber laser. The laser source (especially the pump diodes) generates heat that must be removed continuously. A clogged filter or degraded water reduces cooling efficiency, leading to thermal shutdown, permanent power loss, or catastrophic diode failure. This article provides a step‑by‑step procedure for cleaning the chiller filter screen and replacing the distilled water, based on the Yihai laser-cutting machine maintenance manual (Section 6.1.1) and the chiller manufacturer's recommendations.
The fiber laser source operates at peak efficiency when the cooling water temperature is stable (typically 22–28°C). The chiller removes heat from:
Laser diodes – sensitive to temperature; each 5°C rise reduces diode life by 50%.
Optical components – thermal lensing changes focus position.
Cutting head – prevents overheating of the focusing lens.
Consequences of neglected maintenance:
Issue | Cause | Effect |
|---|---|---|
Clogged filter screen | Debris, algae, metal particles | Reduced flow → high water temperature → laser power drop or shutdown |
Old, conductive water | Ion accumulation (Cu²⁺, Fe²⁺) | Galvanic corrosion of cooling plates; electrical leakage to ground |
Low water level | Evaporation or undetected leak | Insufficient cooling → thermal alarm → laser stops |
Frozen water (winter) | No antifreeze | Cracked chiller pump, laser block damage |
The Yihai manual states: “Replace the distilled water of the chiller to ensure the cleanliness and cooling effect of cooling water.” It is not a suggestion; it is a requirement for maintaining the warranty.
Materials:
Distilled or deionized water (conductivity <10 µS/cm) – 5–15 liters depending on chiller size
Ethylene glycol (if freezing risk) – ratio 3:7 glycol: water for temperatures below 0°C
Corrosion inhibitor (optional, but recommended for mixed metals)
Clean a lint‑free cloth
Soft brush (toothbrush size)
Bucket for old water
Funnel
Gloves and safety glasses
Safety precautions:
Turn off the chiller and disconnect power.
Allow the laser source to cool (wait 10 minutes after powering off).
Depressurize the water circuit by opening a vent or slightly loosening a fitting.
Do not run the chiller without water – pump seals will burn.
Dispose of old water according to local regulations (may contain heavy metals).
The Yihai manual (Section 6.1.1, Figure 6) instructs: “Check the chiller and clean the filter screen. Avoid high temperature alarm caused by poor heat dissipation.”
Most laser chillers have two filters:
Inlet filter – on the water return line to the chiller (cylindrical, clear plastic housing).
Air filter – on the chiller’s air intake (for the refrigeration condenser).
This procedure covers the water filter screen, which is the most critical.
Step 1 – Power down:
Turn off the chiller. Unplug it from the mains.
Close the water supply valves (if equipped).
Step 2 – Remove the filter housing:
Place a container under the filter to catch dripping water.
Unscrew the filter housing (hand‑tight only; use a strap wrench if stuck, but avoid damaging the plastic).
Remove the filter screen.
Step 3 – Inspect the screen:
A clean screen is white or light gray. A clogged screen will be covered with dark debris, slime, or rust particles.
If the screen is torn or the mesh is damaged, replace it (do not attempt to repair).
Step 4 – Clean the screen:
Rinse the screen under running tap water from the inside out to dislodge debris.
For stubborn deposits, soak in a mild detergent solution (not soap) and gently scrub with a soft brush.
Do not use metal brushes or abrasive cleaners – they will damage the mesh.
Final rinse with distilled water to remove tap water minerals.
Step 5 – Clean the housing:
Wipe the inside of the filter housing with a lint‑free cloth.
Check for cracks or O‑ring damage. Replace the O‑ring if it is hard or cracked.
Step 6 – Reassemble:
Insert the cleaned screen back into the housing.
Hand‑tighten the housing. Do not overtighten – plastic threads can strip.
Step 7 – Flush the system (if water is also being replaced; see Section 4).
Step 8 – Check flow:
Restart the chiller. Verify that the water pressure returns to normal (typically 4–6 bar for most chillers).
Listen for air bubbles; bleed air from the highest point if necessary.
The Yihai manual (Section 6.1.1, monthly tasks) includes: “Replace the distilled water of the chiller.” It also notes that the cooling circulating water should be deionized water (distilled water). For winter freezing areas, add ethylene glycol (glycol: water = 3:7).
Condition | Action |
|---|---|
Water visibly discolored (yellow, brown, green) | Replace immediately |
Water age >6 months | Replace |
Conductivity >50 µS/cm | Replace (measure with a conductivity meter) |
After any major repair that opened the cooling circuit | Replace |
Before winter (if freezing risk) | Replace with glycol mixture |
Step 1 – Prepare:
Power off the chiller and disconnect from the laser.
Place a large bucket under the chiller’s drain valve (or the lowest fitting).
Step 2 – Drain old water:
Open the drain valve or disconnect the lowest hose.
Allow all water to drain. Tilt the chiller slightly if needed.
If the water is heavily contaminated, flush the system with clean distilled water (run a separate flush cycle without the laser connected).
Step 3 – Clean the reservoir:
Remove the reservoir cap or access panel.
Wipe the inside of the reservoir with a lint‑free cloth.
Remove any sediment or slime. Do not use detergents – they leave residues.
Step 4 – Flush the system (if contaminated):
Fill the chiller with clean distilled water.
Run the chiller pump (without laser power) for 5–10 minutes.
Drain the flush water. Repeat until the drained water is clear.
Step 5 – Prepare new coolant:
For normal operation: Use distilled or deionized water only. Do not use tap water.
For freezing conditions: Mix 30% ethylene glycol with 70% distilled water (e.g., 3 liters glycol + 7 liters water). Do not exceed 50% glycol – it reduces cooling capacity.
Add a corrosion inhibitor (follow the manufacturer’s dosage).
Step 6 – Fill the chiller:
Pour the new coolant into the reservoir up to the “MAX” mark.
Do not overfill – coolant expands when hot.
Step 7 – Bleed air:
Start the chiller pump (set to a low speed if adjustable).
Loosen the highest fitting in the circuit (e.g., at the laser head) to allow air to escape.
Tighten when water flows without bubbles.
Run the pump for 5 minutes, then check the water level. Add coolant if necessary.
Step 8 – Verify operation:
Set the chiller to the correct temperature (e.g., 25°C for fiber laser).
After 10 minutes, check that the temperature stabilizes and the pressure is normal.
Check for leaks at all fittings.
The chiller’s refrigeration system also has an air intake filter (or condenser fins). The Yihai manual (Figure 6) indicates cleaning the filter screen as part of daily checks.
Procedure:
Remove the air filter cover.
Rinse the foam filter with warm water and mild soap. Squeeze dry (do not wring).
Reinstall when dry.
For condenser fins: Use compressed air (5 bar) to blow dust from the inside out. Do not use a metal brush – fins are delicate.
Frequency: Every 30 days in dusty environments; every 90 days in clean shops.
Based on the Yihai manual and the chiller manufacturer's recommendations:
Task | Daily | Weekly | Monthly | Every 3–6 months | Annually |
|---|---|---|---|---|---|
Check the water level | ✓ | ||||
Check water temperature and pressure | ✓ | ||||
Clean air filter | ✓ | ||||
Clean water filter screen | ✓ | ||||
Replace distilled water | ✓ | ||||
Check hoses for leaks/cracks | ✓ | ||||
Inspect pump seals | ✓ | ||||
Calibrate the temperature sensor | ✓ |
For machines running 24/7, shorten intervals by 50%.
Problem | Likely cause | Solution |
|---|---|---|
Chiller alarms “Water flow low.” | Clogged filter screen | Clean filter; check for kinked hoses |
Chiller runs constantly, cannot reach the setpoint | Dirty condenser coil | Clean the air filter and condenser fins |
Water is discolored (brown) | Corrosion in the system | Flush and replace water; add inhibitor |
Water pressure drops slowly | Leak | Tighten fittings; replace damaged hoses |
The chiller freezes in winter | No glycol | Drain water and add glycol mixture; use a heater blanket |
Laser alarms “Water temperature high.” | Chiller undersized or filter clogged | Clean filter; check chiller capacity |
Parameter | Acceptable range | Ideal | Measurement method |
|---|---|---|---|
Conductivity | <50 µS/cm | <10 µS/cm | Conductivity meter |
pH | 6.5–8.0 | 7.0–7.5 | pH meter or test strips |
Hardness | <5 °dH | <1 °dH | Test kit |
Particles | <50 µm | None | Visual inspection |
Bacteria | None | None | Smell (musty = bacteria) |
Tap water has a conductivity of 300–800 µS/cm and will cause galvanic corrosion within weeks. Never use tap water.
If the chiller is installed in an unheated area and the ambient temperature drops below 5°C:
Option 1 – Add glycol:
Drain existing water.
Fill with 30% ethylene glycol + 70% distilled water.
Note: Glycol reduces cooling capacity by about 10%. Increase chiller setpoint by 2–3°C if necessary.
Option 2 – Use an immersion heater:
Install a thermostatically controlled heater in the water reservoir.
Set to maintain +5°C.
Option 3 – Drain the chiller:
Drain all water from the system.
Disconnect the chiller and store it in a heated area.
Blow compressed air through the hoses to remove residual water.
The Yihai manual warns: “In winter frozen areas, the chiller is placed in an environment below 0°C, it must add a certain proportion of ethylene glycol (ethylene glycol: water = 3:7).”
The chiller filter screen and cooling water are the most neglected yet most critical maintenance items on a laser cutting machine. A clogged filter reduces flow, causing thermal alarms and laser power loss. Old, conductive water corrodes internal components and can short‑circuit the laser diodes.
Clean the water filter screen monthly (or weekly in dusty conditions). Replace the distilled water every 3–6 months or immediately if discolored. Before winter, add 30% ethylene glycol to prevent freezing. Always use distilled or deionized water – never tap water.
A well‑maintained chiller keeps the laser source at a stable temperature, extending diode life and ensuring consistent cut quality. The 30 minutes spent on monthly maintenance prevent thousands of dollars in repairs and days of downtime.
Q: Can I use tap water temporarily if I run out of distilled water?
A: No. Tap water contains minerals that will permanently contaminate the cooling circuit. Even a few hours of operation with tap water can cause scale buildup and corrosion. Wait until you have distilled water.
Q: How do I know if my chiller has a filter screen?
A: Most chillers have a visible filter housing on the water return line (usually a clear plastic cylinder with a mesh inside). Consult your chiller manual. If unsure, contact the manufacturer.
Q: What type of antifreeze is safe for laser chillers?
A: Use ethylene glycol (automotive antifreeze) mixed with distilled water. Do not use propylene glycol (RV antifreeze) – it has lower thermal conductivity. Ensure the glycol is compatible with aluminum and copper (most are).
Q: My chiller water level drops slowly but I see no leak. Where is the water going?
A: Evaporation through the reservoir cap (if not sealed) or through microscopic hose pores. Check for wet spots under the chiller. Also, if the water is hot, evaporation increases. Add a sealed reservoir cap.
Q: How often should I replace the water filter screen itself (not just clean it)?
A: Replace the screen every 12 months or if it is damaged (torn mesh, cracked frame). A damaged screen allows debris to pass into the laser cooling plates.
Yihai Laser Cutting Machine Operation Manual. Section 6.1.1: Daily maintenance of machine tools — check the chiller and clean the filter screen; replace distilled water.
ISO 16162:2012. Cold‑rolled steel sheet products — Dimensional and shape tolerances. (Reference for operating conditions)
IPG Photonics. (2020). Chiller Maintenance and Water Quality Requirements. IPG Application Note AN‑CH‑2020.
Laser Institute of America. (2019). Cooling System Maintenance for Industrial Lasers. LIA Technical Guide TG‑CL‑2019.
Adams, S. M. (2005). Sheet Metal Bend Allowance. KETIV Virtual Academy. (General maintenance principles)
