Cephee IV - Pinhole detector for aluminium foil and thin-strip rolling line



Aluminium foil is a very thin sheet of aluminium which range from 0,006 mm to a limit of 0,2mm as defined by the International Standards Organization.
The aluminium foil manufacturing process begins by rolling sheets of aluminium down to coils between 2mm and 4mm thick. After this process the aluminium coil is then successively cold rolled until the coil reaches the desired thickness.

As aluminium foil acts as a complete barrier to light and oxygen, odours and flavours, moisture, and bacteria, it is used extensively in food and pharmaceutical packaging. 

During the rolling mill process, some pinholes could be formed and could lead to consequential
These holes can not be detected visually.
In order to detect those defects, we propose an automatic detector using the “dark room” principle : the foil of aluminium to be controlled is placed in a dark room with a specific lightening going through the holes in strip in order to activate ultra sensitive photoelectrical sensors.

Cephee-IV is an automatic detector especially designed for foil slitter, doubler or cut-to-length line.  

Please refer to our sensor solution named "Pinhole detection on aluminium foil and thin-strip rolling line" for the description of working principles.  


Performances of the standard product are the following ones :
- Maximum linear speed 23 m/sec or 1 400 m/min
- Detection of perpendicular holes of 30 µm minimum at 700m/mn
- Foil gauge (µm) : 30 to 200
- Aluminium foil
- Width of sheet between 0 and 1745 mm for CEPHEE IV 12
- Range of temperature of functioning from 0°C to +50°C.
- Accuracy of width’s measurement +/- 0,5 mm (option)
- Minimal size of detected cracks : 0,2mm x 1 mm and of edge pinholes, diameter 0,5mm (option).
A better performance could be obtained depending to the residual vibrations of the sheet when running at a high speed.  


  • Pin-hole detection : Cephee-IV performs the detection of pinhole on all the width of the foil except on edge zone measuring maximum 3 mm.
  • Pin-hole position inside a module : The receiver is of type PSD : it is a bar of photosensitive silicon and capable of measuring the average center of the light received on its surface. This represents the position of the hole along its length.
    Such a sensor associated with the processing electronics can therefore :
    - detect a hole larger than 30μm
    - provide its position inside the module.
    The position measurement inside the module is + /-3mm.
  • Pin-hole position inside the equipment : eit is the sum of the pinhole’s position inside one module and the module’s position inside the equipment.
  • Pin-hole position on the foil : it is the difference of the pinhole position inside the equipment ad the foil’s edge position inside the equipment.
  • Type of detected holes : Receivers use a signal able to check the length of the detection signal.
    In case of a short signal, a signal "micro hole" is issued.
    In case of a long signal, a signal "maxi hole" is issued.
    Levels of detection of micro-holes for the two categories are programmable.
    On installation, or on each coil change, the level of detection is defined by software for each detector.
    This can be transformed into a hole size in µm under reserve the operator enters manually the foil’s running speed.

    Depending if the receiver is placed over the strip edge or not, the minimum detectable size is different.
    For a receiver placed over the foil or strip, the minimum size is 30µm at 700m/min.
    For a receiver placed over the foil or strip edge, the minimum detectable hole is upgraded to 100µm no matter the speed due to the laser light going permanently over the surface of the receiver.

  • Edge-mask : Thanks to its edge-mask system, Cephee-IV performs the following functions :
  • - Detection of the position of the foil
    - Detection of crack and edge pinhole on edge zone of the foil
    - Measurement of the foil’s width
    - Automatic adaptation of the system to any foil’s width betw. MIN mm and MAX mm
    - Covering the 2 foils edges over 3 mm.

    This edge-mask system is a multifunctional device avoiding false detections by masking the part of lasers out of the foil (average covering of 3 mm of the foil).
    It authorizes vertical movements of +/-20 mm ; available space inside forks is 10 cm allowing easier passage of welding or coil chaining without accident.


Special micro processing units associated to an interface board drive the receivers for pinhole detection.
It is doing interfaces of Cephee- IV equipment with the external world : static outputs TOR indicating the presence of a defect : functioning defect or pinhole detection, RS485 for the displays and RS422 for communication with a main PLC, providing statistics via a TCPIP link.

  • Management of information received from photodiodes : Signal emitted by photodiode is processed with a low level detection and is amplified before fast trigger inputs.
    This electronics of very fast technology is integrated in each receiver.
    It provides two types of information to the general processing electronics: presence of pinhole and maxi-hole.
    One way of using consists in the use of solid state relays for each level of detection for the communication with the PLC process : eject the sheet in a cutting line.
    An other way consists in memorizing the pinhole information for statistical and graphical analysis in a processing line.
    This information is stored in the processor card and available for HMI display as well as for the Ethernet link with the host.
  • Equipment Management Module (Processor board) :
    - Edge Detection
    - Crack Detection
    - Edge-masks Control
    - Receivers’ Driving and Control
    - Measure of the sheet’s running speed.
  • Display panel : A display is included in the front panel of the electrical box integrated in the equipment frame.
    This display has a few knobs for opening or closing the edge-masks on the sheet, the online installation or the removal of the equipment on the line and a self-testing function of the receivers.
    It indicates the status of edge-masks with green LEDs: opened or closed.
    It indicates the status of the equipment with green LEDs: out off line or in place.
    This display is giving pinhole receiver status (lighting green if OK) and pinhole detection (flashing orange in case of pinhole detection).
    A detailed indication for each receiver module is provided by the PLC.
    This display is giving crack or edge pinhole detector status (lighting green if OK) and pinhole detection (flashing orange in case of pinhole detection). This is available if this option is selected.
    This display panel is interfaced with the micro processing board through an RS485 serial line.
  • Personal Computer for viewing
    Special software on PC gives the following information :
    - Display in real time of pinhole detection / Maxi hole
    - Display in real time of cracks or edge pinholes detection (if option)
    - Display in real time of the edge-mask status
    - Pinhole statistics on coil (if the start / end of coil is saved in the computer):
    - distribution of pinholes on the length of the coil
    - distribution of pinholes on the width
    - graph showing location of the pinhole on width and length of the sheet.
    It also indicates the position of edge pinholes on the sheet.
    - Edition of a report test with all defects detected for each coil.
    The memorization of defects is made by the panel PC. Reset will be made by the user.
    This PC must have a TCPIP Ethernet connection. This may be an industrial PC or a panel PC if installation in a exposed site.
    This connection makes available the supervision data of a coil to the plant’s computer system.


  • Form in "O" 
  • Place of installation :
    On horizontal lines : it is fixed on the ground with the windows at the level of the foil.
    On vertical lines : it is fixed on an existing frame.



  • Dimensions
    Width < 2400 mm (electric cabinet not included)
    Height 1000 mm
    Depth 250 mm
  • Power supply : 230VAC 50 Hz / max. consumption 100W / 16A
  • Cleaning air pressure system (for horizontal line)
    Air pressure : 2kg/cm²
    Air filtration at customer’s charge.
  • Inputs :         
    START Signal : beginning of defect detection
    STOP Signal : end of defect detection
    OPEN Edge-Mask Signal : edge-masks opening
    CLOSE Edge-Mask Signal : edge-masks closure 
  • Outputs :
    Three signals are present :
    - 1 signal of pinhole detection,
    - 1 signal of maxi-hole detection,
    - 1 signal of active zones
    Output "maxi-holes": T = 30 ms
    Output “pinhole”: T = 100 ms
    Output "Active Zone" : 24V indicates all zones which are activated.
    These signals are common to all receivers.
    For each output : optocoupled 200mA, 24 V.
  • Outputs for crack or edge pinhole :
    Two signals are present :
    - 1 signal of crack or edge pinhole detection,
    - 1 signal of equipment status
    Output "crack or edge pinhole": T = 30 ms.
    Output "equipment status" : 24V indicates a good working.
  • Ethernet : TCP/IP protocol (html page) : 1 single simultaneous connection to set the functioning settings of the equipment. 


  • Manual testing tool for pinholes
  • Samples of pinholes of various sizes
  • Supervisory PC and Software


Cephee-IV 09 : with 9 modules of detection - working width of measurement 1310 mm
Cephee-IV 10
: with 10 modules of detection - working width of measurement 1455 mm
Cephee-IV 11 : with 11 modules of detection - working width of measurement 1600 mm
Cephee-IV 12
: with 12 modules of detection - working width of measurement 1745 mm.


Cephee : pinhole detector
Cephee-AS : pinhole detector for aluminium foil separator
: crack and hole detector
Sirius : measure equipment of strip’s width
Orion : painting defect detector

Réalisation SYSTONIC 2008