Maintaining Constant Coolant Concentration

In some machining situations, variations in coolant concentration can affect surface finish, part-to-part consistency...even the useful life of the coolant and cutting tools.

In some machining situations, variations in coolant concentration can affect surface finish, part-to-part consistency . . . even the useful life of the coolant and cutting tools. Until recently there was no practical way to constantly maintain proper coolant concentration, according to Ondeo Nalco (Naperville, Illinois), a producer of synthetic, semi-synthetic and soluble-oil coolants. Now, however, the firm has found a way to do it with its Trasar concentration measurement and control system.

In the Trasar system, an inert, fluorescent “tracer” is formulated into the firm’s synthetic solution coolants and semi-synthetic and synthetic emulsions. The tracer is easily detected by a fluorometer, called the Trasar 3000, which not only documents and stores the data it receives but also activates coolant feed pumps to maintain the desired coolant concentration on a real-time basis. According to the company, the system provides the most precise coolant control available: Detection of the tracer by the fluorescence method is sensitive down to 2 parts per billion.

How It Works

To begin, a coolant sample is captured in a flow cell within the fluorometer. The sample is exposed to a filtered-light source that causes excitation of the fluorescent molecule and ultimately emission of fluorescent light from the sample. A detection device reads the non-visible, emitted light, the quantity of which is proportional to the amount of chemical present in the system sample. The greater the amount of light emitted, the greater the coolant concentration.

Ondeo Nalco notes that, historically, control of coolant concentration was achieved using indirect methods. For example, when makeup water was added to the system, a flowmeter would inject a corresponding amount of concentrate. With indirect methods, however, the amount of concentrate added is based on assumptions, indirect relationships or calculations. The actual concentration is not measured.

By contrast, the Trasar system directly measures the coolant concentration and increases it as needed to maintain the desired level. The improved control, accuracy and system reliability can result in significant savings in the areas of water use, energy, labor allocation, equipment downtime, increased production and process reliability, and equipment cleaning and replacement costs. And because the fluorometer has no moving parts, maintenance and upkeep of the system are very easy.

As an example of the savings that can be realized by using the right concentration of the right coolant, the company cites the case of an Ohio customer, a parts supplier to the auto industry, that had been using a soluble oil coolant for its high-volume OD grinding operations. The customer was experiencing numerous problems, such as burning, excessive coolant consumption, poor part surface finishes, odor and dermatitis . . . to mention a few. The sales rep convinced the customer to switch to an Ondeo Nalco semi-synthetic coolant. Sometime later, the customer also incorporated the Trasar system.

The combined savings for the customer over 15 years has amounted to an estimated $7.5 million, achieved through reduced coolant consumption, tool savings, health and safety issues, reduced wastewater treatment costs, improved part quality conformance, lower external disposal costs (swarf processing), rust prevention and overall improvement in the ability of the firm to satisfy its customers’ manufacturing requirements. Currently, Ondeo Nalco is working with the customer to identify or develop one coolant that will satisfy all of its machining requirements.