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Timely Maintenance Extracts a Higher Market Share
avril 2003

GoonveanGoonvean has been extracting kaolins, china stone, feldspars, and aggregate by-products in England for over two centuries. Kaolin is a fine clay used in ceramics and refractories and as a filler or coating for paper and textiles. The feldspar quarry—the last in the United Kingdom— produces high quality ceramic fluxing agents to compliment the clays.

Goonvean produces about 200,000 tons of china clay per year for paper fillers, paper coating, tableware, porcelain, and pharmaceuticals. Eighty percent of Goonvean’s output is exported to Europe, the Middle East, and the Far East.

The Process
Unlike most manufacturers, Goonvean cannot rely on its suppliers to provide raw materials in a consistent orderly fashion. The mineral has to be won from the ground.

The clay is washed from the slope using high-pressure water monitors and is broken down and carried in suspension to the lowest part of the pit. All subsequent refining of the clay takes place in slurry form (the particles of clay are suspended in water). The pressing and drying of the clay occurs at the end of the processing. Most customers take the clay in bulk by ship. Smaller quantities are bagged for customers requiring lesser amounts.

The Challenge
For the majority of grades, the final process is drying. Goonvean wanted to find an efficient way to schedule production on three dryers to meet the demands of different products. The dryers were scheduled on a grade-by-grade basis—orders for each grade were collected and lumped together on a spreadsheet. For example, 2000 tons destined for items such as sinks might be followed by 500 tons destined for dishes. However, shifting between the different grades can be tricky. Changing to a lower quality product does not require rigorous cleaning of the dryer, but changing to a higher grade does. Every piece of equipment has to be cleaned to prevent contamination, and that takes eight hours of work.

GoonveanThe company needed a more efficient drying operation with fewer time-consuming grade changes.  Maintenance and dryer downtime also had to be taken into account. During a routine inspection, the maintenance manager may request the dryer be down for a number of hours for a specific task It was difficult deciding what the impact on orders would be by stopping production. It was also difficult to quickly identify a gap in the drying schedule that could be painlessly passed over to maintenance.

Finally, Goonvean wanted to keep on top of consignment stock. Consignment stock is when customers pay only for what they take. Goonvean is responsible for keeping the stock levels at consignment stores at appropriate levels. The company wanted to ensure it could replenish stock not when the levels got dangerously low, but when scheduling made it convenient.

At the time, Goonvean was looking to install an ERP system where orders and production could be coordinated. It was during that search that Goonvean learned of Preactor and its finite capacity scheduling tool, Preactor 300 FCS.

A Balancing Act
Preactor 300, a multiple constraint scheduler, helps Goonvean determine the effect on the dryer schedule should an order change or a new order arrive. It helps identify if increasing the tonnage of one grade on the dryer will put subsequent orders behind their due date. Now Goonvean can assess if particular customers can accept a delay of a day or two. Some customers are well organized and can be flexible; others are always ordering at the last minute and could run out of product if the delivery date changes. Since the Preactor installation, there has been a change of scheduling—from clay products to definitive customer orders.

Goonvean now schedules on an order-by-order basis, which gives them a finer granularity of information. By using the matrix of setup times between setup groups, they are able to gather the orders together by families (grades) and schedule them to minimize the number of grade changes. This strategy has prevented the number of grade changes from increasing despite the fact that the number of particular grades for ceramic customers has increased.

Goonvean is now able to give the customer a quick response as to whether and when they can produce an order. If the progress of an order is crucial, the company can use the mid-batch update facility every day or two to get exact confirmation of where it is in the process.

A Smooth Operator
Production runs more smoothly when maintenance is routinely scheduled. By rescheduling back from due dates, it is now easy to spot if there is a gap in the drying schedule. The company can hand a dryer over to the maintenance crews at a specific time. Should maintenance crews initiate the request, production can now react more quickly to the request, since customer order and schedule information is all up-to-date.

Consignment stock is now far easier to maintain at acceptable levels. By scheduling back from due dates, the company can easily and conveniently produce for consignment stock, before it gets dangerously low.

The greatest benefit of using the Preactor system has been transparency. The production department can show sales the impact of a change in shipping.

The most common question from sales is this: Can we fit in an order of grade X by the end of next week? This is particularly important in the ceramics industry. While 35 percent of Goonvean’s production volume is in ceramics (65 percent is in paper), 90 percent of its customers are in ceramics and specialties. Ceramics customers typically place small orders, and it is more complex to deliver many small orders on time than fewer large orders.

By using the Preactor solution and uploading the scheduled production back to the ERP system, the sales team has up-to-date information and can give customers a realistic estimate of when their order will be completed or when a new order can be manufactured.

This has enabled Goonvean to increase its market share in the ceramics industry.