China fit for royalty

With a long established reputation for high quality bone china, it is essential for Wedgwood to manufacture and deliver quality product. A knowledge based system provides the necessary production consistency.

Traditionally a craft industry dependent on the specialist skills of individual workers, the manufacture of bone china is becoming increasingly reliant on automated technology combined with skilled logistics and IT management. With such manufacturing environments becoming increasingly data-centric, the quality of information becomes a vital factor — the smallest inconsistencies are capable of causing significant manufacturing problems. Production tolerances are less than 0.4% and with a capacity of 750,000 units per week, the potential exists for a lot of faulty product.

Ian Ferguson is Manufacturing Systems Improvement Manager and it is his task to develop the process control at Wedgwood. Much of the automation infrastructure is now in place with a fleet of automated guided vehicles (AGV) and an army of robotic arms working with more traditional conveyor belts enabling many key areas to be completely automated. Each automated stage represents a distinct manufacturing island, interconnected with those up and downstream within the process. These changes have already made significant improvements including a massive reduction in work In progress (WIP), substantial time and labour cost savings, and a drastic reduction in order lead-time.

Fundamental problems remain due to the very nature of the industry. Ferguson elaborated: ‘The nature and variety of the raw materials involved in the pottery industry, for example the water content in the clay and the depth from which the clay is sourced, are so diverse that many manufacturers don’t even attempt to control them.’ The situation is complicated by the fact that imperfections that could have originated at any stage of the manufacturing process may often only manifest themselves in a finished batch of ware.

‘If a batch takes a couple of days to complete and only then is a problem discovered,’ Ferguson continued, ‘not only might that whole batch be wasted but potentially all WIP will be suspect. This is more than just wasted stock – it is a customer’s order delayed.’ The sheer scale of variables requiring real time monitoring combined with the need for 100% data accuracy for the control cause major data storage and handling issues.

Ferguson explained: ‘The information generated by the equipment within our manufacturing environment is 100% freely available, 100% real time and 100% accurate. Why should we and ultimately our customers settle for less? The limitation comes in the storage and analysis of such vast quantities of information. Get this stage right, now, and you have the future.’

Wedgwood identified certain key stages. First, it had to be able to trace each and every event that happens to a batch throughout its manufacture to establish the parameters that define the ‘golden batch’ for all possible permutations of raw materials. Secondly, this data had to be fed back into the manufacturing machinery with the results consistently monitored against the golden batch to ensure ongoing accuracy. This would enable any unexpected problems to be dealt with immediately, and permit accurate preventative maintenance schedules to be planned into the manufacturing capacity of the site.

Having identified its requirements, Wedgwood engineers needed to find another company using manufacturing knowledge and control software. They visited Waterford Crystal, a partner company of Wedgwood, which had recently installed a shop floor control system, And this is where Ferguson came into contact with Andrew Bridgeman, Director of Technology at Walsh Automation.

‘It was obvious,’ said Ferguson, ‘that they [Walsh Automation] were head and shoulders above the competition. Of key interest for us was its experience not just at a Scada level but also at an MES level.’ Wedgwood and Walsh both foresaw an imminent technological surge in manufacturing software, especially the advent of process architecture utilising the latest open connectivity and based on OPC standards.

‘We wanted the latest software architecture combined with an upgrade path involving minimum risk,’ said Ferguson. ‘Rapid [from Automsoft] is a plant information management product that links with our Mitsubishi MX2000 — Intellution iFIX — Scada package. We were very impressed by its service and quality and in particular with the assurance that the software would be truly integrated. We saw this as providing a much better working relationship and providing crucial support through the learning curve associated with the software.’

Although the project is still in its first phase, it is helping to identify and resolve key problems in one of the most critical stages of the automated process, the actual formation of the plate itself.

Fed with moisture controlled bone china granulate and binder, the dust press produces a uniform flatware product, ideal for automated printing. A metal punch squeezes the bone china particles against a membrane under hydraulic pressure and forces the granulate to bond in the required shape. As each item passes out of the press the edge is finished automatically. Inconsistencies here can cause significant quality failings further along in the process.

Every aspect of this stage is logged by Rapid. The source of the granulate is read by bar coding and humidity of the clay in each hopper measured. In the actual pressing process the amount of pressure and duration of pressure is monitored and logged by Mitsubishi PLCs under the Scada system before streaming into Rapid in real time. Wedgwood estimates that it will require four months of data stored within Rapid to identify the optimum combination of variables to produce the golden batch.

Ferguson commented: ‘Rapid provides Wedgwood with a sense of immediate hindsight that theoretically becomes the best platform for continuous improvement on automated processes. By doing so, it helps us to manufacture golden batch product all the time, to reduce raw material and energy costs, and to make what the customer wants, when it is wanted.’

Automsoft International

Tel: +353 1 6328610