Optical surface inspection systems are used for a wide variety of web products such as films, metal foils, paper, textiles, etc. Objective information in real time regarding the quality of films is becoming increasingly important in order to save raw material, minimise waste and optimise the production process. In addition, customers, especially in the medical or food sector, demand 100% quality control.
Since the production processes are very fast, defects can only be detected at the required speed with image processing. Line scan cameras or contact image sensors are usually used for these inspections.
Here we focus on two types of foils for which guaranteed compliance with high quality standards is essential:
During the production of films, a wide variety of defects can occur, such as production errors, damage or soiling, which have a direct influence on functionality or appearance:
gels (also gel particles or fish eyes)
streaks, orange peel
bubbles (bonded films)
Flexible packaging foils of all kinds, in a wide variety of thicknesses and colours, from transparent to opaque, structured or coated, are used in a wide variety of applications - from food packaging to tablet blisters to baby nappies. Small local defects must be detected just as reliably as deviations in material properties.
Inspection tasks include checking the homogeneity of the coating and surface structure, reflection, transparency, seal inspection, or checking the adhesive distribution. Specks, fish eyes, holes, inclusions, air bubbles or depressions must be detected as well as contamination.
Continuous inspection makes it possible to detect faults, determine the causes and at the same time optimise the production process.
Detecting defects and deviations on battery foil materials such as anodes, cathodes, battery base foils and aluminium packaging foils is probably one of the most difficult tasks in foil inspection. Here, the porosity, as well as the thickness of the material and the coating, must be checked so that waste is minimised and only defect-free material is further processed.
Coating defects, inclusion defects, strip defects, particle defects, stains, gels, fish eyes and air bubbles must be detected as well as scratches, cracks or wrinkles.
Modern media are placing increasingly high demands on display technology to produce error-free LCD displays. Polarisation films play a key role here, as they determine the brightness and contrast of the display. Here, the smallest defects that can occur during manufacturing, lamination and finishing processes must be detected. Properties of the film, such as colouration or polarisation homogeneity, must be controlled in all production steps. Scratches, lamination defects, bubbles or soiling must be reliably detected.
The technical requirements for a foil inspection system are very high, but to combine them with optimal costs requires a lot of experience. In addition to the selection of the right camera(s), lens(es) and illumination, the most important factor is the algorithm used. The algorithm does not only have recognise and classify the surface (structure), but also recognise irregularities (anomaly detection).
To offer you the right solution, we only need some information from you:
What is the size of the area to be inspected?
What kind of faults need to be detected?
How big/small are the defects that need to be found?
How fast is the material moving?