A summary of some recent MISG projects will demonstrate the diversity of industries and problems encountered in recent years

At Exide’s Elizabeth plant about 50 different types of battery are produced. Each of these products must be charged in a different way and for a different length of time.

Within the factory, movement through the charging area governs the rate of production. It is important to have a constant flow of batteries coming off charge to keep workers occupied in the finishing area, where the washing, labelling and testing takes place.

Exide asked the MISG team whether, for any given product mix, it would be possible to devise a loading schedule for the charging area that would ensure the finishing area was fully utilised.

The analysis conducted by the MISG team showed that a schedule ensuring 9000 batteries a day would reach the finishing area was possible, but that it would require the products which needed long charge times to be loaded and charged over the weekend. Members of the team recommended refining and validating their models, developing a visual display of how the schedule would work, and collecting data on the full and empty stills in the plant automatically.

Modelling of open vat red wine fermenters

During the process of fermentation for red wine, the grape skins are left in contact with the juice in a vat or fermenter. Carbon dioxide gas rising in the fermenter lifts the skins into a porous cap that sits half-exposed on top of the fermenting grape juice. In order to keep the juice in contact with the skins, engineers at Beringer Blass have devised a circulation system whereby grape juice is sucked out from the bottom of the fermenter and sprayed over the surface of the cap. However, this pumpover system tends to cause the grape skins to break up, necessitating expensive filtering at the end of fermentation.

Beringer Blass asked the MISG team to analyse the efficiency of the pumpover system, with a view to determining if the process could be improved.

Relating electricity supply disruption and designated causal factors

Clearly, any interruption to electricity distribution is bad for business. ETSA Utilities must collect information on all power interruptions in its networks and report each quarter to the Independent Industry Regulator on their performance with respect to predetermined targets.

Given that such data has now been collected for more than a decade, ETSA Utilities asked the MISG if it could identify any significant trends, such as where supply interruptions are most likely to occur, and the causes of those interruptions. More specifically the company asked the MISG team to investigate the reliability performance of its networks under adverse weather conditions, and to construct a model to relate measures of interruptions to causes.

The application of pesticides to grape bunches

Pesticides are typically applied to grape bunches using a mechanised sprayer which works its way up and down rows of vines. Different sprayers use more or less air for the liquid volume applied, and create larger or smaller droplet sizes. The concentration of the pesticide mixture can be varied, and it may or may not contain a surfactant. The canopy, bunch distribution and structure onto which the pesticide is sprayed can be radically different for different varieties and climates and for different phases of  bunch development. The Grape Wine  Research and Development Corporation asked the MISG if the chemical application process could be modelled to give an idea of the relative importance of each of these variables in the process.

Efficient design of tall tapered feeders

Toowoomba Foundry makes high quality metal castings for a variety of industries. The metal is cast within cavities hollowed out in sand inside mould boxes. Each iron type used, shrinks as it cools and solidifies. In order to prevent air spaces or "porosity" forming in the cast a reservoir of molten metal, known as a feeder, is connected to it. As the cast cools, metal moves into it from the feeder to plug any gaps which may arise.

The company asked MISG to investigate the most appropriate design features for tall tapered feeders in order to reduce the amount of metal left in the feeder after solidification and hence improve the efficiency of their casting process.

By calculating the movement of heat through the sand packed around the feeder the team found that the sand effectively acted as an insulator. The group also worked out that the height of the feeder would provide little in the way of extra pressure to assist metal flow into the cast. An analysis of the changing heat profile from the walls of the feeder inwards over time, showed that convection within the feeder was keeping the metal at the top molten, and that this was assisted by the tall narrow shape. The team’s analysis provided Toowoomba Foundry with several new avenues to explore experimentally.