KUKA KSS00018 Brake Release Error – Causes, Symptoms & How to Fix

Error Code Overview

• Error Code: KSS00018
• Category: axis / Brake / Motion Safety
• Severity: High
• System: KRC Controller / KUKA Servo Drives (KSP/KPP)
• Impact: axis cannot move, brake fails to release, robot motion blocked

Quick Fix for KUKA KSS00018

If KUKA KSS00018 Brake Release Error appears:

1. Stop all robot motion immediately
2. Ensure the robot is in a safe stationary state
3. Reset the alarm in SmartHMI
4. Check which axis reports brake release failure
5. Retry motion at reduced speed

Tip: Temporary recovery is possible if the fault is caused by unstable brake voltage or a momentary release timing issue.

What Does KUKA KSS00018 Mean?

KUKA KSS00018 occurs when the controller commands an axis brake to release, but the brake does not disengage properly.

The brake release system works by:

• Sending electrical power to the brake coil
• Releasing spring pressure inside the brake assembly
• Allowing the motor shaft/axis to rotate freely

In simple terms:

The robot wants to move, but the mechanical brake remains engaged or partially engaged, preventing axis movement.

Common Symptoms of KSS00018

Typical signs include:

• axis refuses to move after enable
• Robot jerks slightly then stops
• SmartHMI displays KSS00018 Brake Release Error
• High torque spike at motion start
• Servo drive trips during startup
• Brake clicking sound without movement

Main Causes of KUKA KSS00018

1. Low Brake Supply Voltage

Brake coil may not fully energize due to:

• Weak 24V brake supply
• KPP output instability
• Voltage drop under load

2. Mechanical Brake Sticking

Brake hardware may seize because of:

• Long-term inactivity
• Internal contamination
• Worn friction surfaces
• Corrosion/stiction

3. Brake Cable / Wiring Fault

Electrical loss may occur due to:

• Broken brake wires
• Loose connectors
• High cable resistance
• Damaged shielding

4. Brake Coil / Solenoid Failure

Internal brake actuator failure:

• Burned coil winding
• Weak magnetic force
• Partial coil degradation

5. Drive Timing / Signal Issue

Brake release sequence may fail because:

• KSP timing mismatch
• Incorrect brake parameters
• Early torque ramp-up before brake opens

Recommended Replacement Parts

How to Troubleshoot KUKA KSS00018

Step 1 – Identify Affected axis

Use SmartHMI logs to locate the affected axis.

Step 2 – Measure Brake Voltage

Check brake voltage during release:

• Measure under load
• Verify stable 24VDC
• Check for voltage drop

Step 3 – Inspect Brake Wiring

Inspect for:

• Loose connectors
• Broken conductors
• High-resistance cable damage

Step 4 – Inspect Mechanical Brake

Check brake assembly for:

• Sticking/friction
• Wear/debr is
• Spring or disc damage

Step 5 – Verify Drive Signals

Check KSP/KPP status for:

• Brake timing issues
• Drive faults
• Related voltage alarms

Step 6 – Test axis Motion

After repair:

• Clear error
• Jog axis slowly
• Confirm smooth brake release

Pro Diagnostic Tip

Experienced technicians often diagnose KSS00018 by monitoring:

• Measure rake release voltage under load, not just idle condition
• Compare rake activation timing vs motor torque ramp-up
• Check for artial brake release(common hidden fault)
• Monitor axis torque spike at motion start
• Track intermittent faults caused by voltage drop or coil degradation

👉 Many KSS00018 issues are caused by insufficient release voltage or timing mismatch, not complete brake failure.

How to Fix KUKA KSS00018

Dependingon diagnosis:

• Restore stable brake voltage supply
• Replace damaged brake wiring
• Replace brake coil/solenoid
• Service or replace brake assembly
• Correct brake timing parameters

Prevention & Maintenance

To reduce brake failures:

• Test brake function regularly
• Inspect brake voltage periodically
• Prevent long idle periods
• Lubricate/maintain axis assemblies
• Monitor startup torque behavior

Related Errors

KUKA KSS00017 Brake Test Error – Brake validation test failed.
KUKA KSS00016 Motor Stall Error – axis cannot move due to load or blockage.
KUKA KSS00014 Torque Monitoring Error – Torque exceeds configured limits.
KUKA KSS00406 Position Deviation Error – axis deviates beyond tolerance.
KUKA KSS00012 Path Deviation Error – Robot fails to follow programmed path.

⚠️ Closely related to brake system performance, torque interaction, and axis motion stability.

FAQ

Can the robot move with KSS00018 active?

No. The axis is locked because the brake cannot release.

What causes brake release failure?

• Mechanical sticking
• Electrical faults
• Low voltage
• Drive timing issues

How do I fix KUKA KSS00018 quickly?

• Check brake voltage
• Inspect mechanical brake
• Verify drive signal
• Reset and retest Is KSS00018 a serious issue?

  Yes. It directly prevents axis motion and may indicate brake system failure.