from Units: M
"mil [1]
a unit of distance equal to 0.001 inch: a "milli-inch," in other words. Mils are used, primarily in the U.S., to express small distances and tolerances in engineering work. One mil is exactly 25.4 microns, just as one inch is exactly 25.4 millimeters. This unit is also called the thou. With the increasing use of metric units in the U.S., many machinists now avoid the use of "mil" because that term is also a handy slang for the millimeter."
Contrary to the above, I`ve never heard a machinist or mechanical engineer use the word "mil" to mean millimeter. I`ve only ever heard it used to mean 0.001".
PC.
Bookmarks