DuPont is a large global chemical company - employing 100,000 people with 200 manufacturing sites in 40 countries.
Since its founding in the US in 1802 DuPont has been committed to safety excellence, with a philosophy that all accidents are preventable. This commitment has delivered a safety record 40 times better than the US industry average.
DuPont is now making the same commitment to environmental excellence and has set itself the Goal of Zero - zero waste, zero releases and zero emissions - for all its manufacturing sites.
Already good safety and environment practices are yielding significant financial benefits, with 1995 being DuPontís most profitable year ever with earnings of $US 3.3 billion worldwide.
DuPont operates three manufacturing plants in Australia:
- the Bayswater plant, Melbourne is the largest manufacturer of artificial fibres in the country;
- the Girraween plant, Sydney is an agricultural chemical reformulation plant; and
- the Wetherill Park plant, Sydney produces a plastic sheet which is used in window laminating (Butacite®).
This case study describes the cleaner production initiatives that have been implemented at DuPontís Wetherill Park plant.
Butacite® is a tear-resistant laminate made from a polyvinyl butyral resin (PVB). One or more PVB sheets are placed between sheets of glass, such as windscreens or glass panels. The application of heat and pressure initiates permanent bonding between the two layers of glass.
The Wetherill Park plant was established in 1988 to convert rolls of PVB sheeting into pre-cut blanks for automotive windscreens. The sheeting is imported from the US and arrives at the site in rolls with a plastic inner-core, packaged in cardboard boxes.
Cleaner Production Initiatives
A number of cleaner production initiatives have been initiated at the Wetherill Park plant.
Reducing the amount of trim waste generated when the PVB sheet is cut to the shape of a windscreen has been a particular focus for the plant. The traditional process involved cutting the blank so that there was an excess of approximately 100 mm on either side. This allowed easier fitting by the customer. The initiatives to reduce the amount of waste generated when this excess is trimmed of have included:
- reducing the size of the windscreen templates, which has reduced the excess from 100 mm to approximately 10 mm, and
- rationalising the number of windscreen templates from approximately 300 to 200.
Both these initiatives have involved working very closely with the major customers to ensure these changes did not impact on product performance and ease of fitting. As a consequence the amount of 'trim' waste has been significantly reduced.
All cardboard boxes and wooden pallets are recycled or reused. Approximately 2.7 tonnes of cardboard is recycled per month. The polythene packaging material used between the layers of PVB sheeting is also recycled.
The plastic inner cores of PVB rolls are returned to the US manufacturing plants for reuse.
Attention is also paid to the packaging used to transport the PVB cut-blanks to domestic customers. A returnable aluminium tray was designed by staff for daily cut blank deliveries to Sydney based customers. This replaced the previous system of cardboard boxes, of which several thousand were thrown away each year, and has won an internal recognition award. It is now being applied to other DuPont sites.
Advantages of the Process
Economic and environmental advantages from these initiatives have resulted with a reduction in waste going to landfill and re-use of products.
For example, solid waste generation has been reduced by approximately 70 per cent, with a consequent saving of $20,000 a year in waste disposal charges.
Returning the plastic cores to the US has reduced the number of new cores that need to be manufactured. The savings have not been fully quantified, however it has saved $20,000 to $40,000 per annum in material costs alone.
The cost of setting up the returnable aluminium trays was approximately $100,000 which is expected to be re-couped over a two to three year period.
The project aimed at reducing PVB 'trim' waste by reducing windscreen template size and rationalising the number of templates was only completed in April 1997, so figures on cost savings are not available yet. However the benefits include:
- reduction in tipping fees because in-plant trim waste has been reduced;
- improved product yield because more windscreens can now be cut per roll of PVB; and
- savings to the customers due to the reduction in raw material per windscreen.
Cleaner Production Incentive
The major incentive for reducing the PVB trim waste was cost reduction, both within the plant and for the major customers.
The Butacite® Strategic Business Unit in the US started recycling the plastic cores. This initiated management at Wetherill Park to return cores to the US for reuse.
The cardboard recycling scheme was a site initiative. An engineering science student on work experience was asked to set up the waste minimisation scheme. This was an ideal project for work experience as the student could achieve the project within a month and see the on-going benefit of his work.
No barriers were encountered by DuPont.