Office of Technical Assistance Executive Office of Environmental Affairs Commonwealth of Massachusetts

Summary

The Presmet Corporation substituted a synthetic coolant for the sulphurized oil that it had traditionally used as a coolant in its honing process. The environmentally beneficial switch cut the company's coolant purchase costs by two-thirds, while simultaneously reducing the firm's oily water discharges and sparing workers the health problems associated with sulphurized oils.

Background

Presmet is a 250-worker manufacturer of automobile components located in Worcester, Massachusetts. Certain parts made by Presmet require honing to close tolerances. Prior to its first contact with the Office of Technical Assistance for Toxics Use Reduction (OTA), Presmet used a sulphurized oil to lubricate parts during honing. This meant that finished parts had to be washed in hot water in order to remove the oil. (See Figure 1.) The sewer discharges from the hot-water wash tank had exceeded the limits on Fats, Oils, and Greases (FOG) set by the regional sewer authority, the Upper Blackstone Water Pollution Abatement District (UBWPAD).

Toxics Use Reduction Planning

In January 1990, chemical engineer Alan Buckley and manufacturing development engineer Tom Donohue sought alternatives to the sulphurized oil in order to help lower Presmet’s FOG effluents. Through a referral from UBWPAD, Presmet learned of OTA and its workshops on pollution prevention techniques. Buckley and Donohue attended a workshop on metalworking fluids re-use and recycling, and this prompted them to try a synthetic coolant in their honing process.

Toxics Use Reduction Modifications

Since beginning to use the synthetic oil, Presmet has seen no change in the quality of parts, despite the large variety of precision work performed on the honing machines. At the same time, the pollution problems formerly caused by the oil carried off on the parts have been eliminated.

Presmet has noticed some additional benefits of synthetic coolant. The new lubricant cleans up more easily than its sulphurized predecessor, workers no longer suffer from the dermatitis problems associated with sulphurized oils, and Presmet has reduced the liability exposure connected with water discharge and oily waste management.

Results

Reductions Achieved: Prior to its contact with OTA, Presmet used sulphurized oil in two honing machines with oil sump capacities of 64 gallons each. The firm has now entirely eliminated the use of sulphurized oil in its honing operations, and is looking into replacing other straight machine oils with synthetic alternatives.

Economics: Presmet had paid $3.36 per gallon in 1990 dollars for its sulphurized oil. The synthetic replacement has a purchase price of $8.90 per gallon, but it is designed to be used in a 15% dilution. Thus it effectively costs only $1.10 per gallon — or 67% less than the sulphurized oil.

View Figure 1