Environment industries archive
Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.
Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.
|Steel Castings Pty Ltd installed a computerised ‘Autocat’ system to control the addition of catalyst and binder for the production of sand moulds. The finer control of addition rates significantly reduced the number of reject moulds and achieved annual savings of $21,780 from reduced raw sand and chemical costs.|
Steel Castings Pty Ltd operates a foundry located in Port Melbourne, Victoria. The foundry produces high integrity steel, alloy and stainless castings from 50 kg to 5.500 kg in size. It also produces forging ingots to 5.25 tonnes in alloy, stainless and Duplex grades.
Its customers include manufacturers of heavy earth moving equipment and mills and crushers for the mining industry, pumps and valves for the oil and gas industry, parts for the power generation, steel, sugar and paper industries and mooring equipment for the offshore oil and gas industry.
The casting process is achieved by pouring molten metal into a mould. Steel Castings uses sand mixed with binders and a catalyst to produce the moulds. After cooling, the casting is removed from the mould and the sand is discarded. All this discarded sand, which is 97 per cent pure silica sand and 3 per cent sodium silicate, is sent to landfill.
Pouring a mould
Steel Castings used a 6 tonne per hour continuous cold setting sand mixer, plus core making facilities for the production of moulds. In the preparation of moulds, sand is mixed with sodium silicate and an ester-based setting agent. As well as sand discarded from the final moulds, waste sand was generated because of:
The single largest cause of sand wastage was the temperature variation in the new sand. If the sand had only recently been processed (screened and dried) by the supplier prior to delivery, its temperature could be up to 100 degrees Celsius. When the catalyst addition rate was set for a temperature of between 10 and 30 degrees Celsius, this could cause significant problems, including setting of the sand inside the mixer. Conversely, during periods of cold overnight temperatures the sand cooled significantly, resulting in insufficient setting and consequent sagging in the middle of large moulds.
Steel Castings installed a computerised ‘Autocat’ system, for metering catalyst and binder to the sand in the mixing machine, at a cost of $22,700. The Autocat system utilises computer control for dosing of additives, to achieve the optimal ratio of catalyst to binder for the current operating temperature (sand and ambient), and the required curing time to suit the specific mould being prepared.
The system continuously monitors parameters such as sand temperature, ambient temperature, and catalyst flow rate, and changes the catalyst-to-binder ratios and flow rates as required to maintain cure times. The system also blends slow and fast catalysts to give a mix with the correct set time at the correct strength.
Steel Castings has realised a number of benefits from the installation of the Autocat system, including:
The introduction of the Autocat system has achieved attractive cost savings for Steel Castings.
|New Sand||$ 4,780|
|Sand Disposal||$ 700|
|Total Annual Saving||$21,780|
|Payback Period||1.1 years|
The reduction in labour costs also contributed significantly to the savings achieved, resulting in a true payback of closer to six months.
The possibility for reducing sand wastage from the mould preparation activities was identified by the developer of the Autocat system. The developer contacted Steel Castings to see if they would be prepared to trial a prototype of the Autocat system. A 12 month evaluation was extremely encouraging, after which Steel Castings purchased the prototype.
When the company expanded operations in 1992 and installed a second, 12 tonne per hour, sand mixer there was no hesitation in purchasing a second Autocat unit.
There were no significant barriers to the introduction of the Autocat system. In particular the operators who prepared the sand moulds were very receptive to the technology because it reduced the number of defective moulds. There was minimal requirement for retraining.
Steel Castings has continued to benefit from these initiatives.