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High reproduction quality is equally attractive for readers and advertising customers. Orientation towards DIN ISO 12647 helps to maintain a constantly high quality level. The newspaper standard DIN ISO 12647-3 was published in a new version in 2013; our expert was involved in this process and summarised the innovations in an article for WAN-IFRA. Measurements, settings, certification: in these quality assurance topics, we shall be pleased to help you.

Optimising Quality

Certified quality

 

Vis-à-vis the printing company customer, WAN-IFRA-ISO or QUIZ certification confirms that the company has its manufacturing processes under control and uses suitable methods to compensate for natural fluctuations. This creates trust. Our Senior Consultant Moritz Schwarz, as a WAN-IFRA auditor, can award QUIZ and ISO certification.

 

If you would like to know more about certification, please follow the link to WAN-IFRA ...

 

Settings questions

 

There are a large number of workflows, ICC profiles and software tools in which or with which quality-relevant settings can be made. Frequently, the first question is: how can I be sure that the advertising customers' data are correct or can be processed properly? The integration of colour profiles (ICC or Device Link) at the right points in the workflow is an essential precondition for this. The process-dot gain curve is often incorrectly set in the RIP. Screen adjustments are also complicated, so that enormous improvements can quickly be achieved here through the right settings. Fluctuations in the field of CTP exposure and plate development in conjunction with a high dot loss (e.g. -9%) during printing must be detected, minimised and taken into account accordingly in order to obtain predictable results.

Measuring correctly

 

Process control is essential for standardised quality. First the variables are ascertained, and – as far as possible – made measurable. Using suitable methods and tools, fluctuations can now be determined and combated. For sustainable improvement, it is good policy to train the workers, for example in how to handle the existing or new measuring tools. In this training course, the following basic know-how is taught:

  • densitometer

  • CIE colour space

  • ISO standards

  • pH value

  • laser intensity

  • fountain solution conductance

  • tonal value on the printing plate

  • tonal value increase during printing

  • slurring/doubling

  • etc.

"Optimising print quality" project

 

The customer's objective
An international newspaper publisher has its various editions printed in different printing locations distributed throughout the world. Consistently high print quality is extremely important for the publishing house because most of its advertising customers come from the field of luxury consumer goods (watches, jewellery and fashion). To assure quality, the publishing house has its printing companies supplied with standard-newsprint. ISO-compliant data (without control elements) is sent to the individual printing companies daily as PDF files. The printing companies rip the data themselves and can thus adjust the prevalent conditions themselves. Despite this, the print quality at an important printing location did not achieve the required quality and fluctuated unpredictably, so that the publishing house had to intervene and commission our expert.

 

The road to the objective with the printing company

First step: obtain a general impression of the product quality, the existing technology and the workflow settings in the printing company in question. Here, incorrect settings of the Harlequin RIP were already in evidence. A change in the preset halftone dot shape and the correction of the screen angle solved some of the quality problems. To avoid such errors in future, the staff were given instructions and a handout explaining the optimum settings. In the next step, we put a new thermal CTP imagesetter into operation, together with the personnel of the printing company, and calibrated it. For this, a new RIP was set up and integrated in the workflow. This was followed by the examination and adjustment of the existing printing plate measuring unit. Specially created evaluation tables were used for this and placed at the disposal of the printing company workers for future use. With the help of test prints, we then determined the optimum density for covering the ISO 12647-3 colour space, and identified problem areas caused by the printing press itself, e.g. doubling, presetting, startup behaviour and loss of tonal value during printing. We also determined characteristic print curves for 48 AM screens and FM screens, and saved them as different settings in the Harlequin RIP. The staff can now independently adjust the characteristic curves for different imagesetters, the ISO printing press and the four colour separations for changes in the printing conditions (different paper, new type of printing plate, different blanket etc.). Compared with saving all parameters in one overall process characteristic, this process has significant advantages, because the personnel can intervene quickly and directly in the event of discrepancies. Finally, we formulated further measures with investment proposals and fields of action for the staff and the plant, and the printing company implemented these measures independently.

 

Improvement for the publishing house

Thanks to the improved quality in the printing company involved, the publishing house has achieved a more uniform and standardised level of quality. It can retain the existing PDF workflow with the current settings and achieves consistently good results across all printing locations for its critical advertising customers.