We’re considering putting visual inspection systems onto our presses to pick up on a number of occasional intermittent faults. How do they work, and how quickly could we expect them to pay for themselves?
Broadly speaking, there are two types of on-press inspection system for sheetfed presses. The first is a basic network of miniature cameras fitted throughout the press. These provide an inspection of the sheet’s travel through the press, so you can see where a sheet is flicking or dragging, for instance, and correct it. Those systems cost in the region of £10,000 for a standard multi-colour sheetfed offset press, and all the big four press manufacturers in the UK offer some version of it.
The second type is much more sophisticated, and takes the form of a high-speed camera mounted on the last unit of the press. It works by reading a customer pass-sheet and calibrating itself to that standard.
It flags up every deviation from that standard, on a sheet-by-sheet basis as the press is running. It can be set to pick up hickeys, colour variations, skewed sheets, misregister, splashes of ink, any filling-in, even discoloration of board or paper, and sheet creases.
When it detects a sheet that deviates from the pass sheet in any way, this type of camera system can be set to mark the sub-standard sheets: this can be done by inserting a tab before the sheet lands in the delivery, or by giving an audible warning, or by registering it on its control screen, which can also be tied into the off-press control desk. MAN Roland has a sorter, which can divert flawed sheets into a hopper – this gives a 100% good delivery stack.
This second type of system is more expensive – it can cost anywhere from around £100,000 upwards – but the return on investment is excellent. MAN Roland has done some calculations, which are very conservative: if, say, you’re running a job of 32 million sheets at a paper cost of £60 per kilo, and your average spoilage before using an inspection system was 3% and an inspection system cut that down to 2%, you’d save around 320,000 sheets each year, or in money terms £26,500.
You could count on paying for the system inside four years. In more tangible terms, most UK print companies could expect to pay for a system like this in a year and a half.
Gary Doman
We’ve had a request from our local Primary Care Trust to print some documents onto anti-bacterial papers. What are these, and where would we get hold of them?
There has been a surge of interest in anti-bacterial, or more properly anti-microbial, paper in UK hospitals recently, especially in view of the rise in healthcare-acquired infections.
My company, St Andrew Print Solutions, has an agreement with Robert Horne that allows us to
source anti-microbial papers for health-related printing. The type of documents we can now supply
in this form includes casenote folders, X-ray wallets and printed stationery.
The main anti-microbial paper available in the UK is James Cropper’s Docugard, distributed through Robert Horne.
Docugard incorporates BioCote technology, which is an additive containing silver ions added to the pulp at the manufacturing stage. Silver is a natural anti-microbial element, and it causes functions in the bacteria to break down and thereby inhibits bacterial growth.
It’s important to note that BioCote has no effect on the paper’s runnability, absorbency or general performance on-press.
As part of our trials, when we circulated reams of Docugard to our printers, not one reported any problems or even potential problems on-press, on stock weights ranging from 80gsm up to 480gsm. There is no need for clean room conditions at the printer’s either.
James Cropper can make Docugard grades to order in a specific colour, weight and size to suit all kinds of applications.
Ralph Chalmers
In an addendum to January’s Clinic, in which a reader asked about the most suitable inks and processes for printing onto polypropylene, Paul Farrow wrote in to offer the following thoughts:
Provided the correct environment and conditions are maintained, conventional print methods can certainly be successfully employed to achieve the delicate task of printing onto polypropylene and other types of plastic material.
However, the success rate and consistency of quality achieved when doing this kind of work on an occasional basis can be quite disappointing. Moreover it can be a very costly business in the longer term, either through the need for investment in equipment or through the loss of the client due to unsatisfactory results.
Consequently, the majority of companies that experiment using limited investment end up dropping this kind of work like a red-hot potato.
UV offset litho is another means of printing onto polypropylene (and other substrates including lenticular PET and PVC) but it requires some serious investment and expertise to get the best out of it.
The more sensible approach, if the printer has just a single or a few plastic-printing jobs to carry out, may be to outsource the project to an experienced trade printer such as Reflex.
Paul Farrow
