Drilling Ductile

Published Date
June 15,2008 - 10:45:am

Related Glossary Terms

  • coolant

    coolant

    Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

  • flutes

    flutes

    Grooves and spaces in the body of a tool that permit chip removal from, and cutting-fluid application to, the point of cut.

  • titanium aluminum nitride ( TiAlN)

    titanium aluminum nitride ( TiAlN)

    Often used as a tool coating. AlTiN indicates the aluminum content is greater than the titanium. See coated tools.

  • turning

    turning

    Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.

Some coatings, such as TiAlN, enable dry machining when drill ductile cast iron, but coolant is desirable to help evacuate the material's small, curled chips. Flood coolant can be appropriate for holes less than 1.5 to 2 diameters deep, according to Bob Jennings, product manager for Ingersoll Cutting Tools, Rockford, Ill. Jennings noted that the toolmaker offers standard Qwik-Twist replaceable-point drills to drill up to 8 diameters deep.

Ingersoll also offers standard Qwik-Twist tools for drilling 3 and 5 diameter deep holes.Through-coolant is recommended for deeper holes to help evacuate the chips up the flutes and out of the hole. "With any production, high-feed drilling operation, through-the-tool coolant is certainly a requirement," said Jennings. Through-coolant pressure should be at least 150 to 200 psi, he added, but the best performances are achieved at around 1,000 psi. "If there's a knob where you could turn the coolant pressure up," he quipped, "you keep turning it until you take the bark off your hand."