MANUFACTURE OF FABRICATED METAL PRODUCTS # 57

Background

L&J of New England is a Worcester-based company in Massachusetts, United States, specializing in electrocoating (a technique for painting metal surfaces). Since its beginning in 1969, the company has continually expanded operations, and it has become one of the largest electrocoaters in the region, employing 45 workers. L&J also operates a small screening shop.

Electrocoating is achieved by subjecting a metal object to a positive charge while it is submerged in a solution of deionized water and negatively charged paint ions. The charge differential causes the paint to bond to the metallic surface. L&J operates three different lines for small, medium and large parts. The firm uses acrylic (water-based) paints.

The small-parts system consists of a series of six tanks and an overhead oven. A conveyor rack positions metal fixtures above the appropriate tanks, and the tanks are hydraulically raised and lowered to treat the parts as they move down the production line. The metals parts go through six process steps:

The mid-sized system uses extra rinsing steps and a heated iron-phosphate treatment bath for improved paint adhesion. The large system, which handles parts reaching 25 cubic feet, uses a continuously moving conveyor and high-pressure sprays rather than process tanks.

Cleaner Production Principle

New technology

Cleaner Production Application

L&J Vice Presidents Donald and Duncan Leith were aware that some of their processes had excessive water flow rates, and that certain baths were using large quantities of cleaning solution due to the accumulation of grit, oil and surface residues.

At an OTA workshop in 1990, they learned of two simple technologies that addressed these concerns. The first is a filtration device that operates by skimming the surface residue from water and recirculating the clean water back to the tanks. The second is a flow-control device that constantly monitors the cleanliness of a bath and adds clean water only as necessary.

L&J installed five flow-control devices and three filtration units. Flow controls were installed on two tap-water rinses in the mid-sized system and on three tap-water sprays in the large system. Two filters were installed on the initial cleaning tanks for the mid-sized and large systems. The other filter is portable and is used mostly on the iron-phosphate tank in the mid-sized system.

L&J's large electrocoating system :

Environmental and Economic Benefits

L&J reports that the filtration and flow-control devices paid for themselves in the first ten months of operation. The filters cost $2,227 and the flow-control devices cost $2,688, including installation. After deducting the annual operating cost of the filters, L&J experienced annual savings of $1,225 in cleaning solution purchase costs and $4,689 in water and sewer bills. Thus, after the ten-month payback period, savings amounted to approximately $6,000 per year. As a result, L&J's management is actively pursuing other opportunities for pollution prevention.

L&J experienced a marked reduction in water usage. The new filtration system also resulted in dramatic cutbacks in the firm's use of cleaning solution. Far less solution is needed to clean parts adequately and to remove the residue that builds up on the surface of rinse tanks.

Constraints

None mentioned

Contacts

Office of Technical Assistance

Executive Office of Environmental Affairs

100 Cambridge Street, Room 2109

Boston, Massachusetts 02202

Tel: +1 617 727-3260; Fax: +1 617 727-3827

 

L&J of New England, Inc.

Review Status

This case study was received by the Office of Technical Assistance of the State of Massachusetts in the United States. It was edited for the ICPIC diskette in May 1997.

Subsequently the case study has undergone a technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.