How to Use a Refractometer
A refractometer is an investment that pays for itself almost instantly. Properly maintained cutting fluid concentration prevents wasting coolant, protects machines and tools, reduces disposal, and produces better parts. Measuring your coolant concentration with a refractometer takes less than a minute and the payoffs are huge, make sure that your operators know how to use and read a refractometer.
Basics:
When light passes through a prism it is separated into different wavelengths of light (red, orange, yellow, green, blue, indigo, violet). A refractometer works in much the same way except it is the coolant concentration that causes light to “refract,” or separate as it passes through the sample. The higher the coolant concentration, the greater the separation and the higher the refractometer reading.
Taking a reading:
Step 1: Place 1 to 2 drops of cutting fluid, onto the prism glass and close the plate cover. (If you are measuring the current concentration of a sump it is helpful to fill a paper cup with the used cutting fluid and let it sit for 10 minutes so that the tramp oils and fines separate out. After 10 minutes poke a small hole in the middle of the cup and use the stream of coolant to take your reading.)
Step 2: Look through the eyepiece and view the scale. The top portion of the scale appears blue and the bottom part appears white. Take your reading at the intersection of these two colors.
It is important to note that each coolant has its own unique concentration readings. One coolant may have a refractometer reading of 9.2°Bx at 10% concentration (10:1) while another coolant may read 3.3°Bx at the same concentration. Water-soluble oils typically have the highest refractometer scales and synthetic coolants typically have the lowest. Make sure to check with your coolant manufacturer for the correct scale for your coolant.
You are visiting the blog of ITW ROCOL North America. For more information please visit their website at www.rocolnorthamerica.com.Tags: Brix, concentration, coolant, diluting coolant, lubricants, metalworking fluids, refractometer
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January 12, 2009 at 2:58 pm
Have you tried testing digitally? MISCO has a nifty PA201 (0-56.0 brix) model with higher precision.