Cephee AS - Pinhole detector for aluminium foil separator



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.

To obtain the very thinnest foils (gauge ranging from 6 to 30 µm), two foils are laminated simultaneously and separated after this double rolling mill process.

Those thinnest foils could become slightly permeable due to pinholes caused by the production process.
These pinholes can not be detected visually on 100% of the foil.
Cephee-AS is an automatic detector especially designed for foil separator, testing 100% of the two foils at the exit of the separator.

Please refer to our sensor solution named "Pinhole detection in aluminium foil separator" for the description of working principles.


Performances of the standard product are the following ones :
- Maximum linear speed of 16 m/sec or 1 200m/min.
- Detection of perpendicular holes of 15µm in the middle or on the edge if edge masks are positioned.
- Detection of perpendicular holes of 20µm on the optical modules situated behind the slit or of 40µm on the optical modules situated on the edge if not covered by masks.
- Hole position accuracy : +/-1mm for pinhole bigger than 40µm (+/-3mm for 20µm).
- Foil gauge (µm) : 6 to 30.
- Width of sheet between 100 and 2100 mm.
- Range of temperature of functioning from 0°C to +40°C.


  • Pin-hole detection : Cephee-AS perform the detection of pinhole on all the width of the foil. It performs this detection on both upper and lower foils.
  • Pin-hole position measurement on the strip : each detector measures the position of hole on its surface and the main processor calculates the hole position in the width of the foil by making the sum of hole position on the detector and position of detector with the edge of the foil.
    This is the Y position.
    The system enters an automatic calibration procedure at the beginning to determine the foil edge positions. This calibration procedure will give a width result to be checked with the width entered inside the PC. In case of important deviation the PC will refuse to start the pinhole detection. Getting start information from the operator on the PC keyboard, Cephee-AS calculates the length of foil passing through the pinhole detector thanks to the speed information.
    Therefore it has the possibility to place each detected pinhole along the length of the foil: this is the X position.
  • Classification of PH regarding the levels : each small detector in the equipment measures the energy of light arriving through the hole. This gives the possibility to evaluate the hole’s size and classify this hole into different categories pre-defined by supervisory operator : micro hole and maxi hole.
  • Detection of break in the foil : each detector memorizes its status at the beginning of the foil test. Any important and permanent change in the light received form the laser is analysed as a foil break.
  • Pin-hole density : after each reception of a pinhole, the PC memorizes the position of maxi holes and store into the recorded file. During the foil check, Cephee-AS detector evaluates the density of micro hole by length reference of foil. The length reference is pre-defined by supervisory operator and could be as an example of 0,55m corresponding to 1 m² for a width of 1850mm. The PC verifies if the density is lower than a preset value. In case of over value, it indicates a warning in the display.
  • Search of “Pinhole nets” : the PC check if some net of pinhole in specific windows : for example a width of 3mm and a length of 30mm.
  • Graphical presentation of maxi hole position : after completion of the whole coil detection, the PC gives the graphical presentation of holes along the strip. This offers to the operator a quick visual check of the holes in the coil.
  • Statistics : the PC software calculates the repartition of holes in the width as well as in the length of the foil and the operator can set the width of intermediate scan areas. In that case the PC calculates the percentage of holes in each sub-division.
    The PC calculates the distribution of holes in the length and in the width of the foil.


Special micro processing units associated to an interface board drive the receivers for pinhole detection.
It is doing interfaces of Cephee-AS equipment with the external world : static relays, RS485 for the displays, as well as with Display-PC.
This last PC is able to communicate with mainframe through the TCP/IP Ethernet link.

  • Management of information received from detectors : Signal emitted by detectors 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.
  • Auto test function : The equipment performs an auto-test function when there is no foil inside the separator.
  • Position detection : Each detector is able to process the position of the hole it has detected. The hole’s position is made with an accuracy of +/-1mm for mid size hole.
  • Programming of the micro hole’s size : each receiver module normally uses a system of detection on two levels classifying the holes in two categories. A special function
    allows defining the approximate level of detection for the micro-holes.
  • Measure of the running sheet’s speed : The speed should be sent from the supervisory computer in the factory. This is necessary for the pinhole size measurement.
  • Inputs/outputs :
    These inputs are used to :
    - confirm the closing in good position of the laser girder (coming from CEPHEE laser processor board)
    - confirm the closing of the door for operator eyes protection
    - confirm the start of the coil (coming from the separator).

    These outputs are used to :
    - ask the operator to close the door
    - ask to laser girder processor to move girder in closed position
    - indicate upper pinhole Detector ready
    - indicate lower pinhole Detector ready
    - indicate pinhole on upper foil
    - indicate pinhole on lower foil
    - indicate break of upper foil
    - indicate break of lower foil
    - indicate equipment in fault.

  • Display panel : a display is included in the front panel of the electrical box integrated in the equipment frame. It indicates the status of the equipment with green LEDs: working or not. This display is giving pinhole receiver status (lighting green if OK) and pinhole detection (flashing orange in case of pinhole detection).


Specific software has been developed to configure the CEPHEE-AS working characteristics, to give to the operator real time information of the coil inspection and to record the result of the pinhole detection for statistic and detailed inspection of the coil.


  • Three girders system : The equipment is designed with special shape allowing its installation inside the separator.
    It is provided with three girders including all the optical components.
    The upper girder includes receivers. It should be installed between the two rolls of the upper foil.
    A second similar girder also including receivers should be installed between the two rolls of the lower foil.
    These two girders and associated receivers are installed in a fixed position.
    A third girder which contains the lasers for both pinhole systems is placed on the outer side of the separator between the two foils. Its shape is calculated and designed to fit exactly with the lasers positions and with the angle of the two foils.
    The total width of this girder for lasers is less than 133 x 85mm.
    The receiver’s girder is removed when operator works between the foils for maintenance.
    It is mounted on rotating system, fixed at the upper part of separator going up. It is in its upper position when the operators are working to introduce the foils. It should be in the lower position when the operator is welding the foils with ultrasonic system or when he is removing the coils.

  • Girders shape and dimensions :The girders containing all the optical components are designed to be easily installed inside the separator.
    The overall length of the girders will be adjusted to the customer requirements.
  • Laser moving system details : The mechanism is composed by a frame supporting the laser beam. The frame is moved from the opened position to the working position by an electrical motor. 






Cephee : pinhole detector
: crack and hole detector
Sirius : measure equipment of strip’s width
Orion : painting defect detector

Réalisation SYSTONIC 2008