Wadeville, Germiston, is home to the local manufacture of cast brake drums and ventilated disks using the casting processes. To satisfy the stringent acceptance criteria of the major motor manufacturers, the plant recently installed an Adroit supervisory control and data acquisition (scada) system to achieve a fully automated, continuous moulding and sand recycling plant, free of human interference and with full, online record keeping.
Moulding sand
Moulding sand is the key component in quality casting moulds. Good quality moulding sand ensures good quality castings and the site utilises 35 tons of this per hour in the manufacture of car components for all the major motoring brands.
After a casting mould has been used, the useful properties of the moulding sand are lost due to ingredient losses that occur when the hot liquid metals are poured into the mould. During the recycling process, moisture and other ingredients are replenished. The Adroit scada was implemented to precisely control the parameters of the sand on a continuous basis. Foremost among these is the measurement of water content. Water content is kept up to 0,2%.
Recycling the moulding sand
Sand is recycled in a five-day-a-week continuous batch operation. Parameters are entered through the Adroit system and implemented by the foundry machinery, a Compactibility Controller and Bond Determinator (CCBD) then feeds data back to the Adroit. This complex mini-lab (imported from USA) automatically draws samples of the sand and performs a battery of tests on the medium in less than one minute. Each batch is separately numbered for reference purposes.
One of the parameters measured by the CCBD is the bond, which is the term used to describe the binding properties of moulding sand, the ingredient added to recover these properties is a fine clay called Pentenite, that, when combined with water, gives the moulding sand its mechanical strength.
The role of the scada
The CCBD is linked to the scada for online monitoring purposes and to ensure access to the parameters. Adroit Technologies helped set up the communication using Adroit's Ethernet communication features. The plant makes extensive use of the Adroit trending functionality to provide an online reference for plant operators as to the process temperatures, moisture levels and sand water content, and the sand's strength as tested by the CCBD.
Batch reports are printed continuously, while data drawn from a Microsoft Access database provides daily reports on the plant operations and batch statistics - which is then further analysed using Opus reporting software. The scada's onscreen and audible alarming provides notification to operators in case the sand's parameters stray over their limits - or in instances when any plant equipment malfunctions, and the times that these events occur.
The project began in April 2004 and was completed in August.
For more information contact Lisa Giustinoni, marketing, Adroit Technologies, 011 658 8100, [email protected], www.adroit.co.za
| Tel: | +27 11 658 8100 |
| Email: | [email protected] |
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