Related Suppliers.Ingersoll Machine Tools, Inc.. Okuma America Corporation. SETCO. Fly an airplane fast enough,and you meet a threshold. Air can't flow out of the way anymore, so all you can do is plow through it. Accomplish this, and you have broken the sound barrier. Mill an airplane component fast enough, and you also meet a threshold. As spindle speed increases, ultimately it reaches a point where cutting edges are striking the material at a frequency identical to some resonant freque...