On tap

Published Date
August 15, 2009 - 10:00:am

Check out this brief video from Kennamental Inc. showing a side-by-side comparison of an HSS tap vs. a solid-carbide tap. The video accompanies CTE's August cover story on selecting the right tap for different workpiece materials. The split-screen video demonstrates the significant productivity advantage of the first solid carbide tap specifically engineered for tapping steels.

Both the high performance TiN HSS coated tap shown on the left and the new generation solid carbide tap shown on the right were used to tap 1/2" deep through holes in 150 HB 4340 steel. Using a CNC machining center with synchronous tapping capability, the HSS tap was used at the recommended speed, 25 m/min (80 sfm) while the solid carbide tap was used at its recommended speed 100 m/min (320 sfm). In 30 seconds of tapping, the carbide tap produced 36 holes versus 12 by the HSS tap, a 3x improvement in productivity.

The solid carbide tap is manufactured from a patented coated carbide grade developed by Kennametal for tapping steel. The design consists of a precision cylindrical shank, a left-hand spiral flute (RH thread) that directs the chips ahead of the tap in through holes and internal cooling. Other new carbide tap designs are available for blind holes in steel as well as tap styles and grades for cast iron and aluminum. Video courtesy Kennametal.

Related Glossary Terms

  • Brinell hardness number ( HB)

    Brinell hardness number ( HB)

    Number related to the applied load (usually, 500 kgf and 3,000 kgf) and to the surface area of the permanent impression made by a 10mm ball indenter. The Brinell hardness number is a calculated value of the applied load (kgf) divided by the surface area of the indentation (mm2). Therefore, the unit of measure of a Brinell hardness number is kgf/mm2, but it is always omitted.

  • computer numerical control ( CNC)

    computer numerical control ( CNC)

    Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

  • high-speed steels ( HSS)

    high-speed steels ( HSS)

    Available in two major types: tungsten high-speed steels (designated by letter T having tungsten as the principal alloying element) and molybdenum high-speed steels (designated by letter M having molybdenum as the principal alloying element). The type T high-speed steels containing cobalt have higher wear resistance and greater red (hot) hardness, withstanding cutting temperature up to 1,100º F (590º C). The type T steels are used to fabricate metalcutting tools (milling cutters, drills, reamers and taps), woodworking tools, various types of punches and dies, ball and roller bearings. The type M steels are used for cutting tools and various types of dies.

  • machining center

    machining center

    CNC machine tool capable of drilling, reaming, tapping, milling and boring. Normally comes with an automatic toolchanger. See automatic toolchanger.

  • shank


    Main body of a tool; the portion of a drill or similar end-held tool that fits into a collet, chuck or similar mounting device.

  • tap


    Cylindrical tool that cuts internal threads and has flutes to remove chips and carry tapping fluid to the point of cut. Normally used on a drill press or tapping machine but also may be operated manually. See tapping.

  • tapping


    Machining operation in which a tap, with teeth on its periphery, cuts internal threads in a predrilled hole having a smaller diameter than the tap diameter. Threads are formed by a combined rotary and axial-relative motion between tap and workpiece. See tap.

  • titanium nitride ( TiN)

    titanium nitride ( TiN)

    Added to titanium-carbide tooling to permit machining of hard metals at high speeds. Also used as a tool coating. See coated tools.

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