Possibility of Recycling Amine-Free Water-Soluble Coolants

Abstract

To reduce the management cost and environmental load of water-soluble coolants, the authors have been studying a metabolic system for these coolants. In the metabolic system, water resources are recovered from water-soluble coolant waste and reused as a diluent for a new coolant. In this study, we focused on the recycled use of amine-free water-soluble coolants. Most water-soluble coolants contain alkanolamines for corrosion inhibition and pH maintenance. However, alkanolamines are difficult to eliminate from water-soluble coolants in waste treatment by both chemical and physical processes. Some amine-free water-soluble coolants have been developed and are commercially available, and are regarded as environmentally friendly cutting fluids compared with conventional coolants. We examined the recyclability, lubrication, cooling performance, as well as the ability change of amine-free water-soluble coolants. The amine-free water-soluble coolants showed an equivalent lubrication and cooling performance as amine-containing coolants. The recycling processing time of the amine-free coolants decreased by half with our recycling process. The fluctuations in Brix and pH during long-time usage have also been similar to those in conventional coolants. However, the corrosion inhibition performance of amine-free coolants has been inferior to that of amine-containing coolants.

Keywords

• cutting
• water-soluble coolant
• recycle
• green manufacturing
• metabolic system
• amine-free coolant