As a general rule of thumb, MQL applies between 5 to 80 mL/hour (0.2 to 2.5 oz./hour) on tools less than 40 mm (1.57”) in diameter. The amount is dependent on the specific cutting conditions, but fortunately there is usually a lot of latitude on what will work. To make it easy to adjust the output of a Coolubricator, it helps to fix two of the controls first so you only have to adjust one. The settings and process given here assume you are using Coolube and standard Unist nozzles. If you are not you may have to make additional adjustments to find the best setting for your operation.
First, set the nozzle airflow. A properly adjusted MQL system uses just enough air velocity to drive the lubricant to the tool when it is cutting. Setting the air flow higher than necessary will create undesirable fogging of the fluid. On a Coolubricator system, the amount of air that mixes with fluid at the nozzle tip is adjusted with the air metering screw. Turn the metering screw counter-clockwise to increase the air flow and clockwise to decrease the air flow. A good initial setting is open from ¼ to ½ of a turn.
Next, set the pump to a half stroke. This procedure depends on the pump type.
On the standard Unist pumps, rotate the knob clockwise until it stops (full stroke), and then back it off (counter-clockwise) 3 full revolutions.
On the MV style pumps, rotate the knob counter-clockwise until it stops (full stroke), and then back it off (clockwise) 3.5 revolutions.
This middle position generally gives a good spray pattern from our standard nozzles and sets the output so it is easy to know the amount of fluid being dispensed.
Now you can now adjust the pulse generator to vary the amount of fluid dispensed. With the pump at half stroke, the output is approximately 1 mL/hour when the pulse generator is set to 1 cycle/minute. Knowing this, it’s easy to achieve other desired settings. For example, to get 40 mL/hour of output you turn the pulse generator knob so cycles 40 times per minute. Similarly, for 20 mL/hour set the pulse generator to 20cycles/minute.
Less is often more in MQL, so we suggest starting out on the lower end of the MQL range. Often somewhere around 20 mL/hour is a good starting point. As stated previously, this can be achieved with the pump at half stroke and the pulse generator set at 20 cycles/minute (once cycle every 3 seconds). This initial setting will work for most cases, but of course you may have to do some additional tweaking depending on your circumstances.
On the extreme ends of the MQL range, this single-knob adjustment approach may not give the best output results. If you find the fluid output appears to be pulsing with each pulse of the pulse generator, increase the pulse generator rate and correspondingly decrease the stroke of the pump to maintain the same total output. If the pulse generator sounds like a machine gun (more than 1 pulse/second), then decrease its rate and increase the pump stroke.
It is important to note that these adjustments are made once the pumps are primed and ready for use. The pump must be set to full stroke to prime properly and because of this they are set at full stoke when leaving the factory.