Drawings for no fog coolant mister

[terrywerm]

(01-05-2014, 06:13 PM)TomG Wrote: Terry,

Thanks for going to the trouble of posting the drawings of your project, I can definitely see one in my future. What is different about your design and a mist coolant nozzle? Why no fog?

Tom

First, you are most welcome!

Most misting type coolant systems use a compressed air jet through a venturi to create a vacuum at the end of the coolant line. Atmospheric pressure then pushes the coolant into the venturi so that the air stream can carry the coolant to the desired target. This type of system requires very high air velocity, creating high shear forces which tend to atomize the coolant, then carry it onward as a very fine mist. Much of this mist floats about in the air, creating a fog that can be very irritating, not to mention that it leaves an oily film on everything in the area. The high speed air jet also tends to be quite noisy.

This system does a few things differently. First, the coolant reservoir is pressurized to about 5 or 10 PSI. Pressurized coolant then enters the mixing area without the need for a high velocity air stream or a venturi. Instead, the air passage is larger, allowing the air to travel at a lower velocity as it picks up the coolant droplets. They are then carried down the extension tube and out through the .040" nozzle orifice, which increases the velocity of the air and coolant just enough to get them to the target, but without creating the type of shear that atomizes the droplets. Using just enough air to clear the chips from the cutting area combined with just enough coolant to make things damp is all that is required. Due to the reduced volume of air exiting the nozzle, this system is also significantly quieter than the common venturi system.

This design is similar to a commercially available system for which the designer holds a patent. It appears that there is a significance to the size of the hole through which the coolant enters as well as the size of the hole through the nozzle, and the patent holder went through the trouble of experimenting to find out what size hole worked the best.

Now I should mention that if a person were to sell these drawings, or build and sell these systems, he would be guilty of patent infringement, but that is not the case if an individual builds one strictly for his own use.

I have not tested this for myself yet as I am still building mine, but it appears that there may be an advantage to using two separate air pressure regulators; one for the reservoir pressure, and one for the air jet. Terry S built a similar system, but his uses only one needle valve with two regulators. My thought is that this system with two needle valves may negate the need for two regulators, but I will not know that for sure until I complete mine and do some testing with it.