Offset Printing
Mensing sets milestone in print quality monitoring
Monday 19. April 2010 - On-press automated quality control with KBA DensiTronic PDF
Mensing Druck & Verpackung in Norderstedt near Hamburg has been active in packaging printing for more than 50 years, specialising in packaging for pharmaceuticals and cosmetics. At the beginning of 2008 the company installed the first Rapida sheetfed offset press in northern Germany with DriveTronic SPC dedicated drives for simultaneous plate changing. In addition to a high degree of press automation, particular importance was attached to optional equipment for integrated quality assurance and control. It was thus only logical that Mensing should opt not only for DensiTronic Professional colour measurement and control system, but also for a DensiTronic PDF module – the first packaging printer in Germany to do so. The system has now been in use for about a year – time to draw up a first balance.
For managing director Volker Knoop, DensiTronic PDF is the icing on the cake when it comes to quality assurance in sheetfed offset production. While the majority of print companies rely exclusively on colour measurement or control, and only a few perform an additional comparison with a reference sheet, Mensing compares its production with the original PDF files provided by the customer. With an inspection resolution of 36 measuring points per square millimetre, the document comparison reveals even the tiniest deviations in the printed image, many of which would probably have remained unnoticed during a normal check with the naked eye. To this end, the printer on the press uses the KBA DensiTronic PDF system to scan the first good sheet of his run. The automatic evaluation pinpoints even the slightest deviations from the original PDF within just a few moments. Alongside any spots of dirt which may have contaminated plate exposure, the system also detects additional die-cutting and register marks on the sheet, the numbering of individual blanks, dot gain in the packaging barcodes (when printing on inexpensive card grades) and the like. The facility for automatic exclusion of individual detected differences enables the operator to gain a fast and compact overview of all production-relevant deviations. He can then decide whether the job can be printed as it is, or whether consultation with the QA department is necessary.
Certificate of quality print
Mensing Druck & Verpackung implements automatic checks at least three times during its streamlined production process: immediately after making up the sheet, even before the plates are exposed, and then for the first and last good sheets of the production run (see fig. 1). At the end, the customer can request a test certificate and documentation of the results in one of three possible variants, ranging from a simple, single-page statement to a detailed report, either as a PDF file or in paper form.
In the case of pharmaceutical packaging or patient information leaflets, additional comparisons are made in accordance with the sampling intervals specified by the pharmaceuticals industry. This is a field in which the outstanding relevance of DensiTronic PDF is immediately evident. If a “3” in the dosage instructions were to be become an “8” due to a random speck of dust in the platesetter, for example, the consequences could easily prove fatal for the patient. The risk of human error, however, can now be eliminated; deviations are detected with absolute reliability by the scanner. Mensing has fortunately been spared such spectacular errors. But the checks have in the past spotted a plate scratch which was visible in the printed image. The result: production could be stopped and a new plate made before the whole run was printed. On another occasion, a classic pre-press error was detected: the layout cross-hairs had accidentally been exposed onto the plate and would have been printed without further question if it had not been for DensiTronic PDF. In both cases, reprinting of the whole job could be avoided. That saves time, capacity, costs and waste, and is thus also indirectly a contribution to environmental protection. Forme proofs on paper are rendered superfluous by KBA DensiTronic PDF – a further factor in enhanced efficiency.
Since DensiTronic PDF went live the company has been able to reduce its already low costs for returns and complaints by a further 50 per cent. The greatest potential for savings lies in avoiding errors during printing. The facility for density control with DensiTronic Professional and the PDF reader add-on installed on the DensiTronic desk have given a further boost to production reliability and quality awareness within the company. The employees have fully accepted the new electronic tools and are able to feel even more confident in the quality of their work. Besides providing evidence for the introduction of a quality management system “for the production and sale of pharmaceutical, surgical and industrial packaging, patient information leaflets and commercial printing” to DIN ISO 9001:2008, combining the two systems has had an enormously positive effect both internally and outwardly.
Added value convinces old and new customers
As Volker Knoop points out, the marketing value of such quality assurance systems is not to be underestimated: Compared to the major players in the branch, Mensing is a relatively small business with just 45 employees, but is nevertheless listed as a supplier by renowned pharmaceutical companies and other brand manufacturers, among them Beiersdorf, Revell and Johnson & Johnson. Many a customer is currently reducing the number of its suppliers, and it is thus increasingly imperative for packaging printers to develop their unique selling points and to offer the customer added value. The meticulous proof of quality achieved with DensiTronic PDF is a good example of such added value and has been well received by the customers. The mention of effective error prevention has even attracted new customers, and with it a constant increase in order volumes for Mensing. These new customers have so far included manufacturers of agricultural machinery and premium household appliances, among others.
Under its own trademark, “PRINtector”, Mensing draws customers attention to the unique possibilities of electronic quality assurance. The system promises them:
absolute confidence that the delivered product will correspond exactly to the submitted copy, because the printed sheet is compared with the original PDF file and not with a reference sheet (which could itself already contain errors), and is thus superior to any inline monitoring system;
comprehensive test documentation for their own quality management system;
the certainty that even foreign-language texts will be checked exactly, independently of the corresponding language competence of an individual proof editor;
efficient and ecologically sound production through early detection of any errors.
Modern technology can also be used for 8-year-old Rapida
Besides the new Rapida with simultaneous plate changing (photo), the DensiTronic desk and PDF reader also serve a second Rapida press which is already eight years old (6)
Mensing checks every single job for customers in the pharmaceuticals and cosmetics industries with DensiTronic PDF, those for other branches by request. Overall, around two-thirds of the production is now compared against the original PDF file. Besides the new medium-format Rapida the quality assurance tools can also be used to monitor production from a second Rapida which is already eight years old. As the scanner is installed on the desk of the DensiTronic Professional system, the older press benefits similarly from density control. Mensing became aware of DensiTronic PDF at Drupa 2008. Volker Knoop also praises the support for the system. It is a simple matter to shift the threshold settings up or down, and the remote maintenance function is a boon should need arise.
As the new Rapida is configured with DriveTronic SPC for simultaneous plate changing on the whole press in just one minute, Mensing Druck & Verpackung is able to operate very profitably even for the short runs typical in the pharmaceuticals branch. At the same time, however, thanks to the high production outputs of both Rapidas, even runs of a million boxes or more are accomplished with ease, without the need for tricks of any kind. With the backing of such technically perfect equipment, Mensing is now working to continue the optimisation and streamlining of its production processes. Investments to further raise the level of expertise for patient information leaflets have already been realised, for example “Aqua-Scoring” capabilities to assist the folding of the leaflets. The water-assisted scoring process serves to improve the flatness of the folded product (Photo 8).
How DensiTronic PDF works
Operating software for the PDF scanner integrated in the DensiTronic Professional standard user interface
Scanner beam incorporating a series of individual cameras to produce an image every 20mm
Scan resolution 300ppi
Measuring time approx. 60 seconds in 740 x 1060mm format
Individual elements stitched into an overall image on the system computer
Overall image passed to the quality control program
Parallel import of the reference PDF (automatic or manual)
Definition of the monitoring parameters (error size threshold, error contrast, max. dot gain from squeeze, max. register offset, colour mode, resolution) via simple screen menus
Comparison of the overall image against the PDF file
Test certificate plus comprehensive reporting and evaluation functions