Jon Kail, Coates Screen Technical Representative, revisited Walkers recently to assess progress with the companyıs ink dispense installation. 

Walkers of Manchester is a long established and well-respected point of sale producer, servicing large retail outlets in the UK and worldwide. Display graphics are produced on paper, board and flat plastic materials, by screen printing and Walkersı policy is to use state of the art printing machinery to ensure the efficient production of high quality print.

Large format multi-station in line printing equipment such as that used by Walkers requires the use of UV curing screen inks, because rapid inter-station drying is essential. Currently, approximately 60% of work printed is solid colour and 40% is four-colour process.
  

Last year, Walkers took the decision to invest in automatic ink dispensing equipment, choosing from the Coates Screen Colour Management range, and centring on the IDS-LV, (Large Volume Ink Dispenser). This has meant some radical changes to the way in which ink stock control and colour mixing is handled, and we asked Walkersı technical manager, Dave Marshall, to explain why the decision to install this equipment had been made. Dave explained that prior to the installation of the IDS LV, colour and ink management had always been troublesome. When inks matched to a particular colour specification were required, there had been two options - either the colour could be mixed manually, in house, using stock available, or the ink could be ordered pre-mixed from the supplier which could mean an additional matching charge.

Although Walkers had some experience in colour mixing, there was always a necessity to use away large volumes of mixed colour left over from previous jobs, making the task more difficult. This resulted in a lot of time being expended and excess ink being produced because of repeated additions to adjust the colour. Without laborious records being kept of precise recipes, and the composition of the individual inks in the mix was often unknown, so that attaining the same colour a second time was not always straight forward.

To save time and effort it was always tempting to order the mixed colour direct from the ink supplier, erring on the generous side to avoid shortfalls. The problem there was that delivery was delayed whilst the required shade was matched and mixed by the supplier, and with short leads times (as little as 24 hours), being commonplace this led to expensive emergency deliveries, with presses standing waiting for ink. In fact, even when the ink was delivered it was not unusual to have to make some adjustment to the colour to achieve exactly what the customer required under Walkersı printing conditions and this resulted in more delay. Also there was often a significant quantity of ink remaining when the job was complete, which would have to be used away in- house by recombining it to achieve other colours as and when required, which effectively meant back to square one. These types of problems had resulted in a very significant amount of money being tied up in mixed ink stock, as well as delays in production.

Dave pointed out that apart from substrate, ink was Walkersı largest expense on consumables. He knew that they had to find a better way of managing this important area of the business, especially since other production processes which can lead to delay were being greatly accelerated by bringing repro in-house and installing direct projection and automatic stencil reclaiming equipment. Ink preparation now had to be faster just to keep up.

The emphasis is now on the ink recipe, because a precise recipe is needed for entry into the computer database on the IDSıs Ink Manager software. This means that all colour mixes are now accurately reproducible and can be dispensed rapidly at any time, avoiding the wait for ink delivery or preparation, and eliminating human error.

It is no longer necessary to err on the generous side when estimating, rather it is now possible to prepare less than the total volume required for the job initially, and then after actual mileage has been established, the remainder required can be rapidly and precisely dispensed. Since installation the machine has dispensed 15 tonnes of ink which, as Dave pointed out, would previously have meant disposing of 3000 soiled 5kg ink containers, at a cost to Walkers. Obviously containers are still needed to dispense into, but these are often re-used several times for the same colour.

Dave says that Walkers customers are very fussy about the accuracy and repeatability of printed colour and the IDS has proved to be capable of accurate and repeatable dispensing which meets Walkers requirements in this respect. Using press-ready UV ink, which can be used on plastics and paper and board, on all the presses, without adjustment, also greatly aids colour consistency both from print to print and job to job. 

Any small quantities of mixed colour, which are returned from press, are more rapidly used away when a single ink system is in use, because every job is a use-away opportunity. The same ink can also be used to reproduce a given colour on a range of materials.

Dave also mentioned that since installing the IDS, the overall impression created to customers when they visit the factory has been enhanced, customers are impressed with the fact that all areas of the business are managed and controlled efficiently.