10/27/2023 0 Comments Thread forming tap drill sizeThe minor diameter of a formed thread is created by material displacement. Thread flank quality is uniform and size is very consistent. Thread surface finish is also good, improving resistance to corrosion and abrasion. The cold forming process redirects material grain orientation, resulting in thread flanks with higher surface tensile, yield, and shear strengths. The company says this is particularly important for self-reversing heads, because the torque output of a self-reversing head is limited by the size of its components, and cannot match the output of the machine itself.įormed threads are created by material displacement. Torque increases as the tap dulls, and the tap may continue to produce acceptable threads even after the torque required has doubled.īecause of the increased torque requirements, Tapmatic recommends reducing the acceptable tap capacity range for its tapping attachments by 25% when using forming taps. The company explains that thread forming requires more torque than cutting an equivalent thread in the same work material. They also work with tapping heads–either self-reversing or non-reversing–such as those manufactured by Tapmatic Corp. The forming tap, running at the same surface speed, spindle speed of 307 rpm, and feed of 460 mm/min, produced 6240 threads at a cost per hole of $0.01.įorming taps work with standard tapping heads, CNC machines, automatic screw machines, or leadscrew tappers. The cutting tap could produce an estimated 2281 threads at surface speed of 10 m/min, spindle speed of 322 rpm, and feed of 483 mm/min for a cost per hole of $0.02. In one example, the software was used to compare cost of producing a 15 mm deep, M10 thread in B226 aluminum casting alloy. By inputting the work material, thread parameters such as size and tolerances, the type of machine being used, and hole type, users can get a direct economic comparison between thread forming and cutting. Cost per threaded hole can be further reduced by a reduction in downtime normally created by chip problems, tap breakage, and frequent tool replacement.Įmuge offers a computer model service that compares expected performance of forming taps versus thread cutting. The result of higher speeds and longer tool life is higher production rates and lower costs. Spindle speeds at least double those used for cutting taps.Tool life 3 – 20 X longer than cutting taps.This is especially important in smaller thread sizes. Stronger geometries than those of cutting taps, which require flutes for chip removal.Accurate thread size that can be held close to gage limits, improving tap life and reducing the chance of producing oversized threads.Elimination of chip-removal problems and relatively easy threading all the way to the bottom of blind holes.According to Precision Twist Drill (Crystal Lake, IL) potential benefits of thread forming include: Thread forming can also eliminate the need for special taps to produce threads interrupted by longitudinal slots or cross-holes.Ĭold forming can provide multiple processing advantages versus thread cutting. But because thread forming produces no chips, it is especially well suited to tapping blind holes. Thread forming is useful for both blind and through holes, and can produce threads of any length. This list is longer than you might think, and includes wrought and cast aluminum and aluminum alloys, copper, brass, stainless steels, carbon steels, and zinc diecasting alloys. Generally, materials that produce a continuous chip when drilling are good candidates for thread forming. This includes light metals and light metal alloys as well as steels and other materials with tensile strength to 1200 N/mm 2 and hardness below about R C 35 – 40. (Northborough, MA).įorming taps must be applied in materials that cold form well. Tap designs have changed considerably in that time, and speeds up to 260 sfm (79 m/min) are possible with coated taps, according to Emuge Corp. Since the metal’s structure is cold worked along the thread profile, the threads produced are generally stronger and have a smooth, burnished surface finish.Ĭold forming technology has been used to produce threads for more than 100 years. Rather, the process displaces the material to generate the thread form. Unlike thread cutting, no material is removed during thread forming. For ductile work materials, thread forming can provide better size control and stronger threads while improving tool life and productivity. The vast majority of threaded holes–more than 90%, according to one supplier of taps and other cutting tools–are produced using cutting taps.īut many of those threads could be produced using forming taps, which can provide multiple advantages. In the right application, thread forming can boost quality and throughput
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