Product category:
Printing Presses and Machinery (New and Used, Service and Repair)
News Release from: KBA | Subject: Qualitronic II, Rapida 105, Rapida 162a
Edited by the Printingtalk Editorial
Team on 13 January 2006
Software Removes Human Element For
Quality Control
The quality control department at German printer Walter Grieger Offsetdruck no longer relies solely on the human eye.
The quality control department at German printer Walter Grieger Offsetdruck no longer relies solely on the human eye Images from high-speed colour cameras in the company's two large-format KBA Rapida presses are scanned in real time by Qualitronic II software at the control desk and flaws flagged instantly
This article was originally published on Printingtalk on 9 Feb 2004 at 8.00am (UK)
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A family enterprise with 74 employees, Grieger started up as a book printer in Nettetal, near the Dutch border, in 1973 but now specialises in value-added displays, packaging and promotions.
Whilst brand manufacturers generate most of its custom, the contracts are placed by advertising agencies and corrugated processors.
Eighty per cent of total print output is laminated and die-cut externally.
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Alongside sheetfed offset products Grieger's portfolio also includes digital prints on an HP Indigo press and product design from layout and dummy creation to execution with Artwork Artpro.
The sheetfed offset press fleet consists of one B1 (41-inch) and three large-format KBA Rapida presses, each with a board capability, anilox coater and double delivery extension.
The B1 press, an 18,000 sheets per hour (sph) Rapida 105 six colour machine, is about to make way for a hybrid version.
The large-format presses are a Rapida 162a five-colour conventional and UV hybrid press for plastic film and metallised board, a six-colour version of the same type and a new Rapida 142 five colour.
The Qualitronic II systems are fitted in the two five-colour presses.
The entire fleet is linked to a KBA Densitronic S closed-loop colour control system and will soon be networked with a Hiflex management information system via KBA Logotronic and CIP4-JDF/JMF software.
Printshop logistics have also been automated.
The large-format presses have non-stop feeders and deliveries, with pallet transport via roller conveyors and AGVs.
Coating changes have been accelerated and cleaned up with Lithocoat pumping systems from Harris and Bruno.
Both presses are connected to ink pumping systems.
Proprietor and technical director, Wilfried Grieger, is convinced that investing in automation and control systems such as those is indispensable for achieving and maintaining the highest quality standards, whilst boosting cost-efficiency and productivity.
He commented: "Our constant aim is to stay ahead of the field by adopting cutting-edge technology.
And our customers, who demand top quality, reward us with their loyalty." The company also has a training room so that staff can keep up to date with new systems and equipment.
KBA Qualitronic II is just one example of quality assurance at Grieger.
In October 2006 the firm will complete the procedure for ISO 9001:2000 accreditation.
Presses and digital proofer are profiled to ICC standards, and print characteristics are monitored regularly using an in-house test chart.
That will enable the press crew to deliver print without the aid of gamut-expanding colour scales.
If a job entails customer-specific colours, a machine in the laboratory can formulate and mix them from 13 standard colours, including ink recovered during production.
4,000 different formulae have already been stored, said KBA.
The first Qualitronic II inline sheet-inspection system was installed in the five-colour Rapida 162a last April and that has been such a success that Grieger specified it for the Rapida 142 delivered in October, added KBA.
Press operators, who are very conscious of the responsibility they bear in handling costly substrates and large sheets, find it helpful, added KBA.
Size six and seven sheets are simply too big for errors to be detected manually at speed, so the press crew is delighted with a system that detects minimal colour fluctuations (even if they cannot be quantified as definite deviations in density.
It can also detect differences in registration, toning, filling-in of lettering, and build-up of coating at the edges.
It also spots splashes of ink or coating, hickeys and paper flaws down to the size of a pin-head, it is claimed.
In addition to the high-speed inline colour camera the Qualitronic II system includes two monitors and a visual alarm at the console.
The camera is positioned about a metre above the delivery extension, depending on the sheet size.
It is focused through a narrow slit in the catwalk floor and scans the sheets as they pass over the impression cylinder in the coater.
A diode array illuminates the entire sheet width.
The images can be viewed in real time, or individual images frozen at specified intervals for closer scrutiny, in the error monitor.
The system is operated from the second monitor via menus that allow scanning sensitivity to be adjusted individually for different areas on the sheet, and off-specification image areas to be scrutinised in detail.
Print runs range from 50 (for polyglot jobs) to 100,000 sheets.
Qualitronic II is used for runs of 3,000 sheets or more, or some 40 per cent of the company's total output.
Because of the make-ready time involved, manual inspection is more cost-effective for shorter runs.
The first image off the press is captured by the camera and used to set scanning sensitivity.
KBA added that a pre-press image would be of little value because image analysis must be based on an actual print.
Printed areas are then defined, for example, using CF2 die-cutting data from Artpro and the the individual blanks are identified in multi-up production using the die-cutting contour data, so that it is possible to check that each blank is correct - for instance, checking that all the gluing tabs are present and crease lines do not traverse the image.
Individual flawed blanks instead of entire sheets are then tagged.
The tolerance thresholds are determined at which the system should trip an alarm and the statistical parameters are defined.
For example, whether the monitor should update the image every 200 sheets and store an inspection log, and whether faulty sheets should be tagged or errors merely logged.
Walter Grieger Offsetdruck prefers the latter.
A number of sheets are captured shortly after the approval sheet to establish a reference image file.
The system then compares the current camera image with the reference image at maximum production speed and flags each instance of non-compliance with the pre-specified tolerances.
The colour system used is similar to the CIELab gamut and allows colour deviations to be assessed as if perceived by the human eye, said KBA.
Wilfried Grieger said: "Since installing the sheet-inspection system there has been a perceptible improvement in quality.
Qualitronic detects errors as they arise, before a load of sheets have been wasted that no-one will pay us for." Looking to the future he added: "It would be worth thinking about embedding Qualitronic II in a job-tracking system. Request a free brochure from KBA ...
In a networked printing plant it would then be possible to monitor the production run by camera outside the press room, over the internet for example.".
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