Taking a Plunge
Although standard microdrills aren’t generally available below 0.002", microendmills that can be used to “plunge” a hole are. “When people want to drill smaller than that, they use our endmills and are pretty successful,” Burton said. However, the holes can’t be very deep because the tools don’t have long aspect, or depth-to-diameter, ratios. cnc milling machineTherefore, a 0.001"-dia. endmill might be able to only make a hole up to 0.020" deep whereas a drill of the same size can go deeper because it’s designed to place the load on its tip when drilling. This transfers the pressure into the shank, which absorbs it.
Performance offers endmills as small as 5 microns (0.0002") but isn’t keen on increasing that line’s sales. cnc milling machine “When people try to buy them, I very seriously try to talk them out of it because we don’t like making them,” Burton said. Part of the problem with tools that small is the carbide grains not only need to be submicron in size but the size also needs to be consistent, in part because such a tool is comprised of fewer grains. “The 5-micron endmill probably has 10 grains holding the core together,” Burton noted.
He added that he has seen carbide powder containing 0.2-micron grains, which is about half the size of what’s commercially available,cnc milling machine but it also contained grains measuring 0.5 and 0.6 microns. “It just doesn’t help to have small grains if they’re not uniform.”