Making a Deep Hole

Every cutting operation has its own set of parameters that determine the most suitable tool to handle the job. Hole making is no different, with influencing factors such as diameter, depth of cut, and material, as well as requirements for roundness, straightness and surface finish. Making deep holes typically accentuates the difficulty of these requirements.

I recently read an article about one of the most remarkable deep holes ever created. Fifty years ago, the Soviet Union began a project to drill the deepest hole ever achieved. The goal of the Kola Superdeep Borehole project was to penetrate the Earth’s upper crust and sample the area where the crust and mantle intermingle. After years of careful planning for the best methods and location, drilling began in 1962. Although (after decades of work) extreme temperatures eventually led to abandonment of the ultimate goal, the project was not a complete failure. To get as deep as possible, new methods of drilling were developed, and as the project progressed, many secrets were uncovered about what lies beneath the Earth’s surface. It’s really quite interesting what can be found in a hole about 9 inches wide and more than 7.5 miles deep.

Back on our side of the tracks (and on a scale to which we’re more accustomed), we continue to see advances in deep hole drilling as well. Mikron Tool recently introduced a new addition to its Crazy Drill line that is capable of drilling deep holes from 0.1 to 1.2 mm in diameter (increments of 0.01 mm) at depths as much as 30× diameter. Because it combines the flexibility of HSS with the tool life properties of solid carbide, the Flex Drill is less likely to break in the cut because of positioning errors. Read “Micro Drill Cuts to New Depths” for more information about this alternative to gun drilling, EDM and laser machining for the creation of micro holes. You can also view a video of the tools in action.