FEAT RE MACH N FEA ATURE


CHINEI E VISIONISION SYSTEMS M S


Real time filminsp ection wit h speeds of up to 1,200m/mi n


OCS is one of the world’s leading manufacturers of production-integrated fil


to 10 l ne scan cameras suppl ed by Im in can operate side-by-side i systems, enabling defect


lastic films can be found in almost all industries in a wide variety of different thicknesses and colours – transparent or opaque, structured or coated. Applications range fromflat screens,mobile phone displays, pharmaceutical tablet blisters and food packaging to baby diapers. The type and number of permissible defects in extruded filmsmostly depends on their intended use. Reliable detection of defect sizes between 150μmand 500μmis required for packaging film(PET); from 50μmto 200μmin technical film; from 60μmto 160μmin surfac e protection fil m in filmwith


P


specific optical characteri s and from25μmto 100μm


tics .


RELIABL DEFEC IDEN IFICATION process due to incorrectlymeltedmaterial


RELIABLE DEFECT IDENTIFICATION Defects occur during the extrusion


(so-called specks or burnmarks), fisheye, thin places, holes, streaks simply dirt. Machine visio


n is essential to , flow lines or


detect all these defects at the required speed. OCS, in partnership with Stemmer Imaging, has developed a scalable, modular inspection system, which includes up to 10 line scan cameras operating side by side. In practice, most applications use systems with two


cameras for the inspection of filmwidths ranging from1,500mmto 2,000mm. Understanding the requirements of each application is important in allowing the correct configuration to be specified to minimise costs. The attainable resolution (and therefore detectabl e defect size) i s determined by the camera’s sensor size of up to 8,192 pixels (8k) and the camera distance. For example, films for the packaging industry generally do not require resolutions over 150μmto


200μm, which corresponds with the use of one camera per metre of filmwidth.


18 18 DECEMBER/JANUAR 201 ANUARY 2017 | AU AUTOMA MAT ATION


Above OCS nspection sys em in the company’s est centre


Above: O: S inspectioni


system in the company’st ttest centre


set up for testing


Inset: Truecolour system set up for testing


Inset: Tr Truecolour system


the resolution and therefore require a greater number of cameras. The absolute number of pixels in the sensor is not the only consideration. The senso in 8k cameras are small and c


less light-sensitive, so for less light- permeable material, a 4k camera with larger pixel sizes would be the best


choice. The highest resolution required by


width of 1,500mm. This is sol a customer is currently 25µm


synchronised cameras.


In order to manage the amounts of image data resulting from real time production speeds of up to 1,200 metres per minute, each camera is equipped with its own frame grabber T. he widest web section that can currently be inspected at that speed is 870cm wide. The enormous amount of data generated here (up to 400MByte per camera) can only be handled in hardware .


PUTTING PUTTING IT TOGE HER OGETHER


Stemmer Imaging has built up considerable expertise in the pre-


assembly of modules in order to provide support to key customers. This modular approach brings shorter delivery times, higher operational safety and reduced cost and saves a lot of integration time compared to individual components. This is especially important for cu such as OCS which have high


ly complex stomers


optical modules with lenses and filters. In addition, each camera and frame grabber is included in a common housing attached to the machine to minimise the data transfer between camera and frame grabber Integrated cooling f ans


.


generate a slight overpressure to prevent the deposition of production-related dust on the lens. In harsh and extremely


by a separate dust and moist housings are used, which are dirty environments, hermetic


air circuit.


then cooled ally sealed


ure purge


ved with 10 at a web


spection systems. Up mme


scalabl spection a t productio n


speeds of up to 1,200 m tres per mnute Technical films need two or three times


onsequently r elements


S i one of the w rld’s l adi g m nufacturers of production-integrated film inspection systems. Up to 10 line scan cameras supplied by Stemmer Imaging can operate side-by-side in scalable systems, enabling defect inspection at production speeds of up to 1,200 metres per minute


OCS and Stemmer Imaging have agreed on a number of internal standards for cameras, cabling and illumination, leading to special firmware versions for JAI and Teledyne Dalsa cameras, as well as Teledyne Dalsa frame grabbers. LED line lights are supplied in an IP54 protected housing and have lengths ranging from100 to 3,600mmwhich provide a homogenous LED light output, thanks to the diffuser properties in all three axes. A rewinder located in OCS’s in- house test and training centre is used for pre-testing the equipment of a planned system. Sample filmmaterial can be verified under real conditions at speeds of up to 400m/min and systemdesigns can be optimised accord ing to the customer’ s needs. This systemalso allows OCS to test new technologies, including illumination and sensor options, such as Truecolour illumination with independently controllable LEDs and even NIR light .


INSPECINSPECTION FOR PROCESS CON ROL In the current OCS systems all errors are recorded as individual images, which can be evaluated retrospectively. The analysis software developed by OCS provides a choice of error trends, which help derive alarms and specificmodifications of process parameters in the production process. Trend data show tendencies as a result ofmodifications. This way, problems can easily be detected whether it is with certain additives fed, with extraordinary dirt ingress or when changing the pellet tanks, and can then be allocated to certain sections. The defective filmsections can then be cut out in subsequent .


ION FOR PROCESS CONTROL commissioning processes A few years ag o


inspection can be reli increased computing web width was accep an inspection rate of


Stemmer Imaging ww.ste


power, 100 per cent table. Today, with 10 per cent of the


ably provided. www.stemmer-imr-imaging.co.uk in


T: 01252 780000 co.u


AT T: 01252 780000


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