Implementation of Metal Casting Best Practices - EERE - U.S. ...

problems encountered. The assessment team responded to the overview by providing the plant
personnel with an overview of the suite of BestPractices tools and IAC services that are available
at no charge. Plant personnel were unaware of these tools and services and expressed an interest
not only in pursuing an IAC assessment but also in learning how to use and implement the
PHAST, AirMaster+, and MotorMaster+ tools.
1. Implemented Best Practices
Compressed Air
Unlike most plants assessed, this facility is proactive in identifying compressed air leaks. The
plant operates at 200 to 300 hp of compressed air, which is typical for a die casting operation.
The plant has installed a sequencer to maintain its compressed air at approximately 82 psi, which
it uses primarily to blow-clean dies and to operate air knives for the post-casting operations. The
plant has invested in an ultrasonic leak detector that it uses as needed to locate system leaks in
need of repair. The plant engineer, however, noted that the leak detector is not used as often as it
should be. The assessment team ascertained that the only improvement that the facility could
implement to improve its compressed air system is a simple control solenoid. The solenoid
would enable the plant to control the compressed air flow to have it blow to the cutting knives
only when needed, rather than having it blow continuously.
Waste Water Treatment
Plant personnel are also proactive in seeking ways to increase the facility’s profit margin by
improving operational efficiency and reducing waste. The plant’s one concern at the time of the
assessment was the high cost of disposing wastewater. Plant personnel revealed that they pay in
excess of $22,000 a year to dispose of 48,000 gallons of wastewater comprising 90% water and
10% oil. According to the 2005 industry survey by NADCA and the 2005 Confidential
Metalcasting Operational Cost Survey conducted by Sapolsky Research Inc. for AFS and
NADCA, the typical die caster either had a pre-tax profit of 2.87% of sales or a loss of 1.37%.
Therefore, even a small saving can greatly affect the final profitability. To lessen its wastewater
disposal costs, the plant was considering two general solutions: purchasing a Dissolved Air
Flotation (DAF) system, and/or reducing the wastewater volume by installing an evaporation
system. A DAF system employs gravity separation using air bubbles in the water to help float
insoluble material (waste) to the surface where it can be skimmed off. The alternative
evaporative wastewater management solution was estimated to offer a cost benefit when
compared to purchasing a DAF. Although the plant would need to spend time and resources
engineering and constructing the system, it would only have to pay for the disposal of the waste
oil. The assessment team decided that evaporation might be the better solution because the plant
could utilize the waste heat from its reverberatory furnaces to evaporate the water. This would
utilize the energy that is otherwise being lost through the stack of the furnaces and, therefore,
would be an energy-efficient solution to the wastewater problem. The plant personnel are
currently performing the necessary engineering and cost analyses to implement an evaporative
system.
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