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Advantages Roll form taps have neither flutes or cutting edges and therefore do not produce chips and cannot create a chip problem. They are forming tools, displacing metal without removing it in a manner comparable to external thread rolling. The resulting thread is burnished and toughened by the cold forming action. Thread forming offers several distinct advantages over thread cutting for many applications. Materials particularly well suited for thread forming include aluminum, brass, copper, lead, stainless steel, carbon steel, cast steel, leaded steel and zinc. In general, any material which produces a stringy chip is a good candidate for forming. If the chips are powdery, the material may be too brittle. Thread forming offers the following advantages: Chipless Tapping Since the thread is formed and not cut, there are no chip-removal problems in blind holes and the tap can thread easily to the bottom. In addition, there are no chips to contaminate the plating solution in die-casting operations. Improved Thread Gaging Because the forming tap does no cutting, pitch diameter limits can be held close to “No Go” gage limits for added tap life, and the possibility of producing an oversized thread is greatly reduced. The continuous thread of the tap assures accurate lead, thus assuring better control of tapped hole sizes. Reduced Tap Breakage The absence of chips eliminates the need for flutes, and form taps therefore have far more strength in the body than fluted taps, a feature of great importance in the smaller sizes. Tap breakage caused by chip loading is eliminated. Longer Tap Life Because there are no cutting edges to become dull and break down, forming taps can last 3 to 20 times longer than cutting taps. Stronger Threads The grain flow of formed threads follows the contour of the thread, resulting in greater thread strength. Higher Productivity For most materials spindle speeds may be at least double those recommended for conventional cutting type taps. Generally, forming taps extrude with greater efficiency at higher rpm, but it is also possible to run the taps at lower speeds with satisfactory results. No Equipment Restrictions Forming taps work equally well when used in a standard tapping head, NC, CNC, automatic screw machine, or lead screw tapper. It is not necessary to have lead screw tapping equipment in order to run forming taps because the tool will pick up its own lead upon entering the hole. Lower Cost Per Hole Because of longer life, fewer tool changes are required than with cutting type taps. The faster tapping speeds recommended reduce the cycle time on automatic tappers and screw machines to produce more tapped pieces per hour.Additionally the cost per threaded hole can be further reduced by a substantial reduction in downtime normally created by chip problems, tap breakage and frequent tool replacement. Application Information Hole Size The major difference in using forming taps is that they require a larger hole size than cutting taps. Since the material in the wall of the hole is not cut away but rather “flows” into the thread depressions of the tap when displaced by the crest, a larger diameter hole is required. Refer to the Technical Data section for tap drill sizes.

Hole Preparation Because roll forming displaces metal, some metal may be displaced above the mouth of the hole during tapping. For this reason, it is best to countersink or chamfer the hole prior to tapping, so that the extrusion will raise within the countersink area and not interfere with the mating part. Lubrication In general it is best to use a good cutting oil or lubricant rather than a coolant. Sulfur base, and mineral oils, along with most any lubricants recommended for use in cold extrusion or metal drawing have proven best for this work. ‘Lube’ Grooves The Roll–Form comes standard with 2 to 4 grooves, depending upon size, extending the full length of the thread to assure lubrication in the forming zone and to eliminate the build up of hydraulic pressure in blind bottoming holes. Blind Holes Whenever possible in blind holes, drill or core deep enough to permit the use of the plug style. These tools, with four threads of taper, will require less torque, will produce less burr upon entering the hole and will give greater life. Available Styles Roll form taps are available in plug or bottoming styles. Size nos. 0 – 3 are furnished bottoming style only without taper and with points full. These can be removed upon request. Other sizes as follows: Plug Style – This style is thread relieved, utilizes a 4 thread taper point — 4 threads of taper to the first full form sizing thread. The taper permits easy starting. Application: Through holes, or blind holes where there is ample clearance. Bottoming Style – This is the same as Plug style, except that it has a 2-thread taper point and has the male center removed on sizes No. 4 and larger. Application: For use as a bottoming tap. Torque The torque requirements are generally higher than those for cutting taps. Where the operation call for 75% of thread or less, the torque required varies with the material from no additional torque to double the amount. On most applications, therefore, conventional single spindle equipment is suitable. In multiple spindle applications, the required torque must be carefully evaluated. Pitch Diameter Limits Because thread forming displaces material which has a tendency to close in after being displaced, pitch diameter limits of forming taps have to be higher than those recommended for cutting taps. Refer to the Technical Data section for recommendations. Cored Holes Cored holes may be tapped with forming taps provided that the core pins are first changed to form the proper hole size. Because core pins have a draft or are slightly tapered the theoretical hole size should be at a point on the pin that is one-half the required length of engagement of the thread to be formed. In designing core pins for use with these taps a chamfer should be included on the pin to accept the vertical extrusion.