Ford Australia Pty Ltd

Replacement of Hot Caustic Paint Stripping Process with High Pressure Water Jet System: Ford Australia

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Courtesy of Ford Australia Pty Ltd

Ford Australia Ltd replaced an existing hot caustic paint stripping process, used for cleaning car skids, with a high pressure water jet system. This project has resulted in annual savings in the order of $300,000 from reduced chemical, energy and waste disposal costs. Significant improvements in paint quality were also achieved through the ability to clean the skids on a more regular basis than had been possible previously. This cleaner production success has given Ford the incentive to look for other opportunities to improve its environmental performance and reduce costs.

Background

Ford Australia Ltd is one of three Australian manufacturers of passenger vehicles and is a recognised Australian icon. The company operates an engine plant at Geelong, Victoria and an assembly plant at Broadmeadows, Melbourne. In 1992, Ford participated in a Cleaner Production Demonstration Project managed by the Victorian Environment Protection Authority and Business Victoria. This project focussed on the cleaning of the skids used for transporting car bodies through the paint shop at the Broadmeadows plant.

The Process

Ford uses approximately 1700 skids for transporting the cars through the assembly process. These skids circulate through the plant on a random basis. As these skids pass through the painting operations, they receive a coating of paint (overspray from the car body painting operation). As the skids circulate through the painting process, the paint buildup increases to the point where they require cleaning. The skids were cleaned once every 18 months on average by immersion in hot caustic tanks. The tanks were open, and required large amounts of energy to maintain the required temperature. Heating was provided by steam generated in an on-site boiler. The heat losses from the system were estimated at 80 per cent.

 Investigation of contamination sources in the painting process indicated that the skids were a significant source of dirt, and that an optimum cleaning cycle of three months was desirable. The hot caustic cleaning process was relatively slow and inefficient, and meant that the skids could not be cleaned as regularly as required.

Cleaner Production Initiative

  • A number of technologies were investigated to replace the caustic process, including shot blasting, sand blasting, fluidised bed stripping and chemical stripping.
     
  • After careful consideration, a process utilising a high pressure jet of water operating at 15,000-20,000 pounds per square inch was chosen. The water jet undercuts the paint and lifts it off the skid. The paint residue, in the form of flakes and suspended particulate matter, is separated from the water by a filtration process and then disposed of in the general waste stream. The company is still evaluating the possibility of recycling the water in the cleaning process.
    Since participation in the Cleaner Production Demonstration Program, Ford has implemented a number of other initiatives at the Broadmeadows plant, including:
  • A planned upgrade of the paint facilities and change to a water-based process. While this has clear benefits in reducing the amount of solvent used in the painting process, it has the disadvantage of being more energy intensive as it requires higher heat inputs to cure the coating. Ford is currently looking at optimising the paint application and curing process to minimise the additional energy input that will be required.
    Implementation of an energy monitoring process which involves 25 'smart' meters and 6 gas meters which record energy consumption at 15 minute intervals. It is intended to link this system up with the Geelong engine, stamping and casting plants to provide almost instantaneous energy use data. The information gathered from this system will provide valuable data for energy demand management within the plant.
    A number of initiatives to address waste water generation are currently being evaluated, including a total water balance for the site, recycling of treated effluent, collection and use of stormwater from roofed areas and development of a wetland system for water storage and treatment.
    Exploring the opportunity for component suppliers to use reduced levels of packaging, within the constraint of providing effective protection of the components. This would help reduce the amount of cardboard and plastic, which together currently contribute significantly to the total waste stream. 

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