Taps and Threading Tools

July 22, 2021
Taps and Threading Tool Universal Tap Grinding Solution

Rollomatic, a leading machine tool manufacturer based in Le Landeron, Switzerland, maintains its global leadership position in the field of multi-axis CNC grinding by presenting a variety of tool holding and software solutions for the production grinding of taps, threadmills and forming taps. The GrindSmart® 630XW is a modular tool grinding machine that provides ultimate versatility through customizable options. The ShapeSmart® NP50 is a pinch/peel grinding machine which is used for the blank prepara•on of these threading tools both in carbide, HSS and stainless. 

Rollomatic has developed and refined several grinding processes that allow short and long batch grinding of threading tools where external thread grinding is an essential part of the manufacturing process.

  • Cutting taps in HSS and solid carbide
  • Surtical taps in stainless
  • Straight-flute taps
  • Spiral-flute taps
  • Taps with gun point and/or chamfer
  • Custom threads
  • Threadmills in solid carbide
  • Forming taps

Blank preparation including grinding of the shank, square and male centers

GrindSmart® 630XW 6-axis tool grinding machine: 

  • With 6-station wheel and nozzle changer
  • Automatic tool loader/unloader
  • Linear motion technology for improved surface finish
  • Universal workhead with high-speed capability to combine high-accuracy cylindrical grinding and geometry grinding
  • Large variety of workholding and tool holding solutions including custom-made fixtures
  • Laser measuring included

ShapeSmart® NP50 5-axis pinch/peel cylindrical grinding machine: 

  • Automatic 3-axis tool loader/unloader
  • Pinch/peel grinding process in combina•on with V•block part support and with simultaneous grinding of roughing and finishing passes 
  • Multi-pass grinding for efficient heavy stock removal 
  • Amazingly large diameter range from 0.0008” to 1” 
  • Patented non-round pinch/peel grinding for all non-round shapes such as square, rectangle, oval, corner radius and any other non-round profile
  •  Onboard diameter gauge included 

Different types of tool clamping and support systems are available: 

  • The tap can be held between centers. The centers can be male or female on both the workhead and the tailstock. The tap is driven by a square clamp that acts as driver. The concentricity is provided by the two centers and not by clamping on the square. 
  • The tap can be clamped on the shank by a collet and supported by the tailstock. This mimics the way the tap is engaged in the ma•chine tool to cut the thread. 

On-board dressing: 
During the grinding process, the thread grinding wheel may potentially lose its profile and causes the thread dimensions to be out of tolerance. Utilizing predetermined parameters, a rotary onboard dresser will alloy the wheel to be conditioned for optimal grinding performance, while truing and restoring the form simultaneously. Here are diamond dressing rolls that can be used to dress diamond and CBN threading wheels including vitrified bonds: 

  • CVD or natural diamond rolls, hand-set or random-set
  • Impregnated diamond rolls (sintered)
  • Plated diamond rolls 

Automatic loading/unloading: 
The Rollomatic-designed high-speed tool loader which is integrated into the basic machine has been developed with rapid setup speed in mind, using pre•calibrated cassettes and a gripper design that allows holding different diameters without having to reset the gripper positions. The Rollomttic automatic loaders are known to be the most reliable in this industry. Mechanical quick-release clutches allow a rapid and easy recovery from any setup error. 

The difference between cutting taps and forming taps: 
As the name suggests, cutting taps produce threads by progressively cutting away the space between threads into which the fastener's external threads will fit. Forming taps, by contrast, remove no material. Instead, they move or displace material inside the hole to build up the threads and dig into the grooves.
The difference between taps and threadmills: 
Thread milling uses helical interpolation for cutting the thread, while a tap is advanced into the workpiece in line with the center of the tool.

Related Glossary Terms

  • centers


    Cone-shaped pins that support a workpiece by one or two ends during machining. The centers fit into holes drilled in the workpiece ends. Centers that turn with the workpiece are called “live” centers; those that do not are called “dead” centers.

  • chemical vapor deposition ( CVD)

    chemical vapor deposition ( CVD)

    High-temperature (1,000° C or higher), atmosphere-controlled process in which a chemical reaction is induced for the purpose of depositing a coating 2µm to 12µm thick on a tool’s surface. See coated tools; PVD, physical vapor deposition.

  • collet


    Flexible-sided device that secures a tool or workpiece. Similar in function to a chuck, but can accommodate only a narrow size range. Typically provides greater gripping force and precision than a chuck. See chuck.

  • 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.

  • cubic boron nitride ( CBN)

    cubic boron nitride ( CBN)

    Crystal manufactured from boron nitride under high pressure and temperature. Used to cut hard-to-machine ferrous and nickel-base materials up to 70 HRC. Second hardest material after diamond. See superabrasive tools.

  • cylindrical grinding

    cylindrical grinding

    Grinding operation in which the workpiece is rotated around a fixed axis while the grinding wheel is fed into the outside surface in controlled relation to the axis of rotation. The workpiece is usually cylindrical, but it may be tapered or curvilinear in profile. See centerless grinding; grinding.

  • dressing


    Removal of undesirable materials from “loaded” grinding wheels using a single- or multi-point diamond or other tool. The process also exposes unused, sharp abrasive points. See loading; truing.

  • gang cutting ( milling)

    gang cutting ( milling)

    Machining with several cutters mounted on a single arbor, generally for simultaneous cutting.

  • grinding


    Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.

  • grinding machine

    grinding machine

    Powers a grinding wheel or other abrasive tool for the purpose of removing metal and finishing workpieces to close tolerances. Provides smooth, square, parallel and accurate workpiece surfaces. When ultrasmooth surfaces and finishes on the order of microns are required, lapping and honing machines (precision grinders that run abrasives with extremely fine, uniform grits) are used. In its “finishing” role, the grinder is perhaps the most widely used machine tool. Various styles are available: bench and pedestal grinders for sharpening lathe bits and drills; surface grinders for producing square, parallel, smooth and accurate parts; cylindrical and centerless grinders; center-hole grinders; form grinders; facemill and endmill grinders; gear-cutting grinders; jig grinders; abrasive belt (backstand, swing-frame, belt-roll) grinders; tool and cutter grinders for sharpening and resharpening cutting tools; carbide grinders; hand-held die grinders; and abrasive cutoff saws.

  • grinding wheel

    grinding wheel

    Wheel formed from abrasive material mixed in a suitable matrix. Takes a variety of shapes but falls into two basic categories: one that cuts on its periphery, as in reciprocating grinding, and one that cuts on its side or face, as in tool and cutter grinding.

  • 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.

  • interpolation


    Process of generating a sufficient number of positioning commands for the servomotors driving the machine tool so the path of the tool closely approximates the ideal path. See CNC, computer numerical control; NC, numerical control.

  • milling


    Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.

  • recovery


    Reduction or removal of workhardening effects, without motion of large-angle grain boundaries.

  • 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.

  • threading


    Process of both external (e.g., thread milling) and internal (e.g., tapping, thread milling) cutting, turning and rolling of threads into particular material. Standardized specifications are available to determine the desired results of the threading process. Numerous thread-series designations are written for specific applications. Threading often is performed on a lathe. Specifications such as thread height are critical in determining the strength of the threads. The material used is taken into consideration in determining the expected results of any particular application for that threaded piece. In external threading, a calculated depth is required as well as a particular angle to the cut. To perform internal threading, the exact diameter to bore the hole is critical before threading. The threads are distinguished from one another by the amount of tolerance and/or allowance that is specified. See turning.

  • tolerance


    Minimum and maximum amount a workpiece dimension is allowed to vary from a set standard and still be acceptable.

  • truing


    Using a diamond or other dressing tool to ensure that a grinding wheel is round and concentric and will not vibrate at required speeds. Weights also are used to balance the wheel. Also performed to impart a contour to the wheel’s face. See dressing.