Original Date: 06/26/1995
Revision Date: 01/18/2007
Best Practice : Spring Coating Environmental Requirements
As the result of the Pennsylvania Department of Environmental Regulations (PaDER) provisions of the Federal Clean Air Act Standards, Dayton Parts, Inc. (DPI) determined that two different coatings used on assembled springs were non-compliant. The coatings (one a black, tar-based coating for multi-leaf springs and the other, a zinc-based coating for tapered springs) contained excessive volatile organic compounds (VOCs) for meeting the new PaDER requirements. Faced with the expensive options of either purchasing equipment to capture VOCs or incurring progressive fines, DPI took steps to identify, test, and utilize new coating materials that would fully meet the new environmental standards. This requirement for identifying new coating materials with acceptable levels of VOCs was complicated by additional needs to meet salt spray tests, application-ease requirements, and simple part preparation, in addition to presenting a satisfactory finished appearance. The time available to find a solution was also limited by the regulating agency.
To meet these requirements, DPI formed a Project Task Team with representation from the plant’s production, manufacturing engineering, maintenance, purchasing and product engineering elements. The team developed solution parameters which included the range of environmental concerns (PaDER, employee exposure, and waste disposal issues), quality issues, process capacity, and projected costs in addition to the time deadlines. Discussions were held with numerous paint manufacturers regarding the coating needs and revealed a concurrent requirement that thorough pre-application cleaning was a specification included with many of the suggested materials. After investigating cleaning methods, the team determined it should avoid coatings with pre-cleaning requirements if possible because of potentially high added costs and the environmental/safety problem associated with many cleaning methods.
A number of sample products were obtained from paint manufacturers and all were submitted to salt spray testing durations compatible with the quality requirements of DPI. Paints passing the first salt spray tests were subjected to additional similar tests as well as ASTM-specified tests (hardness, chip resistance, and adhesion) where applicable. The results of these tests, together with application methodologies and costs considerations, prompted the team to recommend a water soluble alkyd-based paint as a replacement for the black coating and a water-based, high performance vinyl coating as a replacement for the zinc-based coating. Neither required a pre-application cleaning of spring assemblies.
DPI, through successful team investigation, has found replacement coatings for both product lines that exceed environmental VOC requirements and require no pre-application cleaning. Implementation is ahead of the PaDER required timetable. Tests prove that both replacement coatings may be applied using the cost-effective method of dipping, and then air drying. This application method will eliminate over 90% of the labor required for the replaced zinc-based coating. Implementing the replacement coatings saved over $500K compared to adding environmental control equipment to original processes.
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