I will explain in a very simple way how to switch ON and OFF a CNC machine safely. This startup and shutdown procedure is commonly followed in CNC machines using controls like FANUC, Siemens, and other industrial control systems. Although small differences may exist between models, the basic power sequence remains the same. This is very important for beginners, operators, and students who are working in workshops or training centres.
Many machine problems start because of improper startup and
shutdown. So always follow the correct sequence.
Let us understand it step by step.
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How to Switch ON a CNC Machine
Before starting, make sure:
- Main
power supply is available
- No
emergency button is pressed
- Air
pressure and coolant levels are normal
- Machine
area is clean and safe
Now follow this order.
Step 1: Switch ON the MCB (Main Circuit Breaker)
First, go to the main electrical panel.
Switch ON the MCB (Main Circuit Breaker).
This gives the main power supply to the machine system.
Without turning ON the MCB, the machine will not receive
electricity.
Always ensure:
- No
sparks
- No
burning smell
- Proper
voltage supply
If anything looks abnormal, do not proceed.
Step 2: Switch ON the Stabiliser
After turning ON the MCB, switch ON the voltage stabiliser.
The stabiliser controls voltage fluctuations and protects
the CNC control system.
CNC machines are sensitive. If the voltage increases or
decreases suddenly, the control system may get damaged.
So always:
MCB → Stabilizer → Machine
This sequence is very important.
Wait for a few seconds for the voltage to stabilise.
Step 3: Turn ON the Main Machine Power Knob
Now go to the CNC machine.
You will see the main power switch or knob on the machine
body.
Turn this knob to the ON position.
After this, you will see the CNC control panel start.
The screen will light up.
The control system begins booting.
Do not press any buttons while it is loading.
Let it complete initialisation.
Step 4: Press the Green Button (Control Power ON)
After the control panel is fully ON, press the green button
on the control panel.
This activates the machine drives and servo systems.
Now the machine becomes ready for operation.
Check whether the “Servo Ready” indication light is ON. If it is not ON, press RESET and ensure the emergency stop is released.
You may hear:
- Hydraulic
system sound
- Servo
ready sound
- Cooling
fan running
That means the machine is ready.
Step 5: Release Emergency (If Required)
Check if the emergency stop button is pressed.
If pressed, rotate and release it.
Then press RESET on the panel.
Now the machine is completely ready.
Important Check After Startup
After switching ON:
- Check
the air pressure gauge
- Check
lubrication level
- Check
coolant level
- Move
axes slowly in jog mode
- Take
the machine to the home position
Never directly run the program after startup.
Always take the machine to the home position first.
Important Safety Warning
Never switch OFF the MCB directly while the machine is running.
Always follow the proper shutdown sequence.
A sudden power cut may cause:
-
Servo drive error
-
Parameter loss
-
Alarm on next startup
-
Control system damage
Always treat CNC control like a computer system.
How to Switch OFF a CNC Machine (Proper Shutdown)
The shutdown procedure is equally important.
Never directly switch OFF MCB first.
Follow the reverse order safely.
Step 1: Stop Machine Operation
First stop running program.
Make sure:
- Spindle
stopped
- No
tool cutting
- Coolant
stopped
Step 2: Set Turret to Home Position
Before switching OFF, always move the turret to the home
position.
Why?
If the turret is left near Chuck, and the next day, power is
turned on, it may create a collision risk.
So:
- Take
the X axis to the safe position
- Take
the Z axis to home
- Ensure
no tool is near the job
Safety first.
Step 3: Press Red Button (Control Power OFF)
Now press the red button on the control panel.
This turns OFF servo drives safely.
Wait until the screen goes OFF.
Step 4: Turn OFF Machine Main Knob
After the control panel shuts down, turn OFF the machine's
main power switch.
Step 5: Switch OFF Stabiliser
Now go to the stabiliser and turn it OFF.
Step 6: Switch OFF MCB
Finally, turn OFF the MCB.
Shutdown order:
Red button → Machine knob → Stabilizer → MCB
Why Sequence Is Important
If you switch OFF MCB directly while the machine is running:
- Data
may be corrupted
- Servo
alarm may come
- Drive
failure may occur
- Parameters
may get damaged
CNC control systems must be shut down properly, like a
computer.
Common Mistakes Beginners Make
- Forgetting
stabiliser
- Switching
OFF MCB directly
- Not
taking turret to home
- Ignoring
air pressure
- Not
releasing the emergency stop
Avoid these mistakes.
Final Advice
Always follow:
ON Sequence:
MCB → Stabilizer → Machine Power → Green Button
OFF Sequence:
Red Button → Machine Power → Stabilizer → MCB
If you follow this method daily, your CNC machine will run
safely for many years.
Common Mistakes While Starting a CNC Machine
Switching on the machine without turning on the stabiliser first.
-
Pressing the green button before the screen fully starts.
-
Forgetting to release the emergency stop button.
-
Not checking air pressure, oil level, or coolant before starting.
Running the program without taking the machine to the home position.
Frequently Asked Questions (FAQs)
1. Why should we turn ON stabilizer before the machine?
Because CNC control systems are sensitive to voltage
fluctuation. A stabiliser protects electronic boards.
2. What happens if I switch OFF MCB directly?
It may cause control damage, parameter loss, or servo
alarms.
3. Why should the turret be at the home position before
shutdown?
To avoid a collision when starting next time.
4. Can I skip pressing the green button?
No. The green button activates the servo drives. Without it,
axes won’t move.
5. Why wait after turning ON machine knob?
Because the control system needs time to boot properly.
6. What if the emergency stop is pressed?
Release it by rotating and then press RESET.
7. Is the startup procedure the same for all CNC
machines?
Basic idea is the same, but small differences may exist
depending on the machine model.
8. Should coolant be ON during startup?
No. Coolant is used only during machining.
9. How long should I wait after turning ON stabilizer?
Wait 5–10 seconds for the voltage to stabilise.
10. Why is proper shutdown important?
Proper shutdown protects drives, the control system, and
machine life.
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