Position: This page is about the new weighing and batching control system form Philips for making printing inks.
When one of the UK's leading manufacturers of printing inks for the major newspaper and publishing groups, decided to update its manufacturing systems with the installation of a new automatic weighing and batching control system, the company called in the expertise of Philips Weighing to provide
As part of the project, Philips Weighing designed, installed and commissioned a complete recipe-management and batching and weighing system for two plants, based on its advanced compression loadcell technology and computer-based management control systems. With the new systems, throughput capacity, quality control and overall efficiency have significantly improved.
Everything is done by weight, from mixing raw materials, through combining intermediates, to automatic packaging and shipping the finished product. Before, everything was weighted on flour scales using portable mixing vessels which were moved around the plant. This involved the manual opening and closing of a lot of valves, taking up a lot of time and manpower.
Improved the system
The new automatic weighing system has improved the control of the process, which in turn, has brought a number of benefits. Automation leads to a reduction in manual input and associated costs. Speeding up the process increases production. By reducing the possibilities for human error, there is less waste. By integrating automatic weighing into the plant there is no need to move equipment around, thereby creating a cleaner more efficient working environment.
The first of the two plants to have the automated weighing system installed, produces 'publication gravure' inks which are used in the printing of glossy magazines. The majority of the inks produced here are the basic primary colours: magenta, cyan, yellow and black.
Gravure inks have a low flashpoint, below ambient temperature (less than 20 [degrees] C), therefore the production area at Ruabon is designated 'Zone One' hazardous and all electrical equipment must be flameproof.
In order to meet the demands of the hazardous area, Philips installed a remote-control unit, PR1628, with intrinsically safe interfaces to its equipment.
At the second site, the ink company manufacturers oil-based black inks for the newsprint industry, supplying most of the major newspaper groups. The requirements were basically the same as those for the first plant, except this time there was no hazardous area.
Premixed
The process at both sites is very similar. Raw materials are stored in tanks. The ink is premixed using powders and solvents, then transferred to a postmix area where further mixing is carried out before finally being stored in holding tanks.
Philips PR6211 compact compression loadcells are used to monitor the weight of all the tanks. These leading-edge loadcells combine sophisticated mechanical design with well-proven strain gauge technology. Hermetically sealed to IP67, their all-stainless-steel design provides the utmost reliability and continuous operation even under extreme conditions. Unlike shear beam loadcells, the Philips compression loadcells have a very high overload capacity, i.e. they continue to provide accurate readings even after being subjected to a load much greater than their rating, unlike shear beam units (which could be irreversibly stressed).
The second site utilises 42 weigh points, all of which use PR6211 loadcells and are monitored by PR1613 weight indicators. Phillips installed 12 batching controllers, PR1613/20, for the mixing operation which are linked to a PR1640 recipe-management systems, and 26 PR1613/20 weight indicators for the storage vessels. At the first site, the loadcells feed into PR1613/20 batching controllers installed on 18 vessels and are again linked to a PR1640 recipe manager.
Real-time
The PR1640 recipe-management automatic weighing and batching system is a Windows-based central recipe-control station, designed to provide real-time process monitoring for applications with discontinuous batching processes and frequently changing recipes.
The PR1640 enables up to eight different recipes to be controlled and monitored and, when the sequence is controlled by external PLC, each recipe can control several PR1613/20 batching controllers.
A further three PR1613/03 units with batching software were installed at each plant for filing operations. Most of the finished product is shipped via tankers, ad tanker loading is carried out using a loss-in-weight system from the storage vessels. Facilities for filling one tonne and two tonne tanks as well 10kg and 25kg drums have also been installed.
