Service Home Minimum Quantity Lubrication - Troubleshooting Guide - TG0102
Last updated: 10/14/2025

Minimum Quantity Lubrication - Troubleshooting Guide

TG0102

Introduction

Atomizer needle valve [1]

Oil Reservoir [2]

Symptom Table

Symptom Possible Cause Corrective Action
Low or no oil from MQL nozzle Needle valve not properly adjusted. Adjust needle valve
Clogged filter Service the MQL filter
MQL reservoir air regulator not properly adjusted Adjust air pressure at the reservoir
The reservoir is out of oil. Fill the reservoir with oil.
Too much oil from MQL nozzle Needle valve not properly adjusted. Adjust needle valve
MQL reservoir air regulator not properly adjusted Adjust air pressure at the reservoir
No air pressure to reservoir or from the AAG Solenoid does not operate. Check solenoid power.

Mixture Adjustment

Corrective Action:

Close the atomizer needle valve. Then open it 1/2 to 1 turn.

Set the pressure for the MQL oil regulator to 30 psi (2.1 bar).

Press [SHIFT] and then [COOLANT]. Press [RESET] to stop the air/oil flow.

With the system on hold, place a small piece of paper or cardboard approximately 3" from the atomizer. A round wet pattern will show if oil is being supplied from the MQL nozzle.

 Note: Some oils have a higher viscosity. Oils with higher viscosity flow slowly. The oil flow may need to be adjusted for different tools, workpieces, programs and the type of oil that you use. Adjust the reservoir air pressure high enough to atomize the oil and carry the oil to the tool. To correct oil flow, adjust the air pressure at the regulator on the reservoir and the atomizer needle valve as needed until the correct flow is achieved.

Solenoid

Corrective Action:

Measure the voltage to the solenoid. Make sure the solenoid receives 120 VAC.

If the solenoid does receive voltage, go to Solenoid - Troubleshooting Guide to troubleshoot the solenoid.

If the solenoid does not receive voltage, go to I/O PCB - Troubleshooting Guide (Classic Haas Control) to troubleshoot the I/O PCB.

Filter

Corrective Action:

Lock out and tag out the machine and wear proper PPE (personal protective equipment)

Remove these components: the reservoir bowl [1] from the oil-reservoir assembly for the MQL, the oil hose [2], and the fitting [3] for the oil hose.

Blow debris out of the filter. Use compressed air and hold a towel under the reservoir to catch the debris.

Install these components: the fitting [1] for the oil hose, the oil hose [2], and the reservoir bowl [3] for the MQL assembly. Fill the reservoir bowl with oil before the installation.

[POWER ON] and [ZERO RETURN] the machine. Purge the air from the system:

  1. Find the atomizer needle valve [1].
  2. Turn the needle valve counterclockwise (2) full turns from the closed position.
  3. Set the oil regulator pressure to 40 PSI (2/8 bar).
  4. Command this code in MDI mode: M83;
  5. Run the MQL system [2] until no air is in the system.

Operate the purge until the spray nozzle disperses mist continuously for (20) seconds.

Press [RESET] to cancel the purge cycle.

Oil Level

Corrective Action:

Visually check the oil level in the reservoir. If the oil level is too low, or empty, the MQL nozzle will not spray oil. Fill the reservoir with oil.