Factory Acceptance Test (FAT) Checklist for PLC Functions on Roll Forming Machines

Introduction — Why FAT Is Critical for Roll Forming PLC Systems

A Factory Acceptance Test (FAT) verifies that the roll forming machine control system works correctly before the machine leaves the manufacturer or retrofit workshop.

The FAT focuses heavily on PLC functionality because the PLC coordinates:

• machine sequences
• safety systems
• motion control
• encoder length measurement
• punching and shear systems
• stacker automation
• alarms and diagnostics.

Performing a structured FAT ensures that control logic errors are detected early, before the machine is installed at the customer’s facility.

Without a proper FAT, problems may appear later during commissioning when production pressure is high and troubleshooting becomes more difficult.

A well-designed FAT checklist allows engineers to verify every PLC function in a controlled environment.

Objectives of a PLC FAT

The PLC portion of the FAT aims to verify several key areas.

These include:

• correct input and output wiring
• accurate machine sequences
• proper safety behavior
• correct alarm handling
• reliable HMI communication
• accurate length measurement
• synchronization of cutting and punching operations.

The goal is to confirm that the control system performs exactly as specified.

Preparing for the FAT

Before performing the test, several preparation steps are required.

Engineers should ensure that:

• the PLC program is finalized
• the HMI project is loaded
• electrical wiring is complete
• I/O devices are installed
• test materials are available if required.

Proper preparation ensures that testing proceeds efficiently.

FAT Documentation

The FAT should be documented in a structured checklist format.

Typical documentation includes:

• PLC version number
• HMI version number
• hardware configuration
• test results for each function.

This documentation becomes part of the machine’s technical records.

PLC Hardware Verification

The first step of the FAT is verifying the PLC hardware configuration.

Checks include:

• PLC CPU model and firmware version
• installed I/O modules
• communication modules
• power supply voltage.

Engineers should confirm that the installed hardware matches the design specifications.

PLC Program Version Check

Before testing begins, confirm that the correct PLC program version is loaded.

Verify:

• project revision number
• program checksum if applicable
• backup files stored.

Using the wrong program version can invalidate test results.

Power Supply Verification

The PLC and control system must receive stable power.

Checks include:

• 24V control supply voltage
• power supply redundancy if installed
• correct grounding connections.

Stable power ensures reliable PLC operation.

Input Signal Testing

Each PLC input should be tested individually.

Typical inputs include:

• emergency stop signals
• guard door switches
• proximity sensors
• limit switches
• pressure switches
• panel detection sensors.

Engineers should verify that each input changes correctly in the PLC diagnostics.

Output Signal Testing

PLC outputs must be verified to ensure correct control of machine devices.

Typical outputs include:

• motor contactors
• hydraulic valves
• punch solenoids
• shear solenoids
• stacker actuators.

Each output should be activated manually and confirmed physically.

HMI Communication Verification

The PLC must communicate correctly with the HMI.

Checks include:

• real-time machine status display
• button commands transmitted to PLC
• parameter adjustments working correctly.

Operators must be able to control the machine through the HMI interface.

Start and Stop Function Testing

The FAT should verify basic machine control.

Tests include:

• machine start command
• machine stop command
• emergency stop response
• system reset behavior.

The PLC must respond correctly to all operator commands.

Interlock Testing

Interlocks ensure that the machine cannot start unless all required conditions are satisfied.

Typical interlocks include:

• safety circuit healthy
• hydraulic pressure OK
• shear home position
• punch home position
• stacker ready status.

The PLC should block startup when any interlock condition is missing.

Safety System Testing

Safety systems must be verified during FAT.

Typical safety checks include:

• emergency stop activation
• guard door opening
• safety relay behavior
• motor shutdown response.

The machine must stop immediately when safety conditions are triggered.

Encoder Function Testing

Encoder systems measure strip movement and control length.

Tests include:

• encoder signal detection
• pulse counting accuracy
• direction detection
• speed measurement.

Engineers should confirm that the PLC calculates length correctly.

Length Measurement Verification

Panel length control should be tested carefully.

Typical tests include:

• setting different panel lengths
• verifying encoder scaling
• confirming accurate cut positions.

Accurate length control is essential for product quality.

Shear Control Testing

The shear cycle must operate correctly.

Typical tests include:

1 shear command triggered by PLC
2 blade moves down
3 blade returns to home position
4 PLC confirms cycle completion.

Sensors must correctly confirm blade position.

Punch System Testing

If the machine includes punching, the punch cycle must be verified.

Tests include:

• punch trigger timing
• punch position sensors
• tool protection interlocks.

Correct punching ensures accurate hole placement.

Flying Shear Synchronization Testing

For machines with flying shear systems, synchronization tests are critical.

Engineers should verify:

• carriage acceleration
• speed matching with strip
• cut timing accuracy.

These tests confirm that the shear can cut while the strip moves.

Stacker System Testing

Stacker systems must handle panels reliably.

Tests include:

• panel detection sensor response
• panel counting logic
• bundle drop sequence
• stacker arm movement.

The stacker must operate without causing panel jams.

Alarm System Verification

The PLC alarm system must be tested thoroughly.

Typical alarm tests include:

• simulated sensor faults
• hydraulic pressure alarms
• encoder failure alarms
• stacker jam alarms.

Each alarm should display correctly on the HMI.

Manual Control Testing

Manual control functions allow technicians to operate machine components during setup.

Typical tests include:

• manual shear operation
• manual punch operation
• manual stacker movement.

Manual functions must work safely and predictably.

Automatic Sequence Testing

The automatic production sequence should be tested completely.

Typical sequence verification includes:

• material feeding
• punching operations
• cutting operations
• stacking operations.

The PLC must coordinate these processes correctly.

Network Communication Testing

Industrial communication networks should be tested.

Examples include:

• PLC to HMI communication
• PLC to drive communication
• PLC to remote access devices.

Stable communication is essential for system reliability.

Fault Recovery Testing

The PLC must handle faults safely and allow proper recovery.

Typical tests include:

• sensor fault recovery
• drive fault reset
• machine restart after fault.

Operators must be able to restore operation easily.

Production Simulation Testing

Before using real material, engineers often simulate machine operation.

Simulation tests verify:

• sequence timing
• alarm handling
• sensor logic.

This step helps detect programming errors.

Final Functional Verification

After individual tests are completed, the entire system should be tested as a whole.

Engineers should run the machine through a complete production cycle and confirm:

• correct sequencing
• accurate panel lengths
• reliable operation.

This confirms the PLC system is ready for installation.

FAT Documentation and Sign-Off

Once testing is complete, the FAT results should be documented.

Typical documentation includes:

• completed checklist
• recorded test results
• engineer signatures
• customer approval if applicable.

This confirms that the PLC system meets project requirements.

Benefits of a Structured FAT

A structured FAT provides several advantages.

These include:

• early detection of programming errors
• reduced commissioning time
• improved machine reliability
• better customer confidence.

For roll forming machines, a thorough FAT ensures smooth startup at the production site.

FAQ — PLC Factory Acceptance Testing

What is a Factory Acceptance Test?

A FAT verifies that a machine and its control system operate correctly before shipment.

Why is FAT important for PLC systems?

The PLC controls the entire machine sequence, so verifying its functions prevents problems during commissioning.

What should be tested during PLC FAT?

Inputs, outputs, safety systems, machine sequences, alarms, and communication networks.

Should HMI functions be tested during FAT?

Yes. HMI communication and operator controls must be verified.

Can FAT be performed without running material?

Yes. Many functions can be tested through simulation or manual triggering.

What happens after FAT is completed?

The machine is approved for shipment and later undergoes site acceptance testing during installation.