CNC milling Cooling and Lubrication
Milling creates friction and friction produces heat. An overheated cutter loses its
hardness, rendering it useless. A common way to reduce friction and heat is to use
cutting oil.
The simplest way to apply cutting oil is to spray it from an aerosol at regular
intervals while you work. Using small quantities of oil this way is known as min-
imum quantity lubrication (MQL). However, MQL is not always practical and sim-
ply applying more oil doesn’t really make sense. In contrast, pro-grade machines
often have a built-in lubrication system.
If MQL doesn’t provide sufficient cooling to prevent damage to the cutter, you
can use a cooling lubricant to provide constant cooling and simultaneous lubri-
cation. Cooling lubricants are applied for the entire duration of a cut using a pump
system with an adjustable nozzle, and your machine has to have a system for
removing excess lubricant once it has done its job.
Fluid coolants are not suitable for use with wood or other absorbent materials,
and the coolant of choice in such situations is compressed air. The poor conduc-
tivity of wood exacerbates the issue, making it essential to stick to appropriate cut-
ting speeds. A cutter that gets too hot can even set fire to a wooden workpiece.
