![]() This is because cut taps will cut slightly larger than their P.D. The 2B fit has a larger tolerance and requires a larger H-Limit than a 3B fit.Īlso remember that the H-Limit for a cut tap is different than the H-Limit for a form tap. A 3B fit is used where closeness of fit and or accuracy of thread elements are important. A 2B fit is the most commonly used thread class for general applications. The two primary gauging standards are 2B fit and 3B fit. The one reason for the specialization of the pitch diameters is the various gauging standards. PITCH DIAMETER LIMITS FOR TAPS THRU 1” DIAMETER is, notice that the tolerance for any h-limit is. You can use the following chart to determine what the H-Limit’s P.D. The Metric tolerance for D-Limits is slightly larger than the tolerance for H-Limits, but for our purposes we will assume they are the same. The metric equivalent to H-Limits is D-Limits. This indicator shows the amount over the Basic P.D. the Actual P.D. of the tap was ground. The H-Limit number is an indicator, which provides information regarding the specific pitch diameter (P.D.) of the tap. The H-Limit’s are used to adjust the size of the pitch diameter to provide for a good mating of the external parts. Not only is it important that the hole is large enough to allow the bolt to enter the hole, but it is equally important that the hole is not so large as to create a loose fit. The basic goal of all tapping functions is to insure that the external part (bolt) correctly mates with the internal threads (nut). ![]() This condition has been used in brass applications with some success. NITRIDING (NQ-5)- case hardens the cutting tool surface to 66-68 Rockwell C and provides increased wear resistance with a black surface finish that acts as lubricant to reduce frictional heat and galling.īRIGHT- provides no surface treatment. STEAM-OXIDING (J-100)- provides a diamond blue/black finish that stress relieves the microstructure of the tap and provides an oxide film that reduces galling. This treatment works well in brass applications. This treatment reduces the coefficient of friction and helps prevent galling. This treatment is designed for titanium and high nickel alloys and has worked well in galvanized steel applications.ĬHROME PLATING (KF1-B)- provides a layer of hard chrome which is electrochemically deposited on the surface of the tool. ![]() CrN coating has a hardness of 75-80 Rockwell C. Titanium Nitride is the standard treatment on all Stub Jarflo taps.ĬHROMIUM NITRIDE (CrN)- provides a coating applied with the physical vapor deposition method (PVD). This treatment is not recommended for tapping titanium and has performed poorly in high nickel alloys, brass and galvanized steels. ![]() The TiN treatment is ideal for the majority of forming applications. This treatment reduces the coefficient of friction and hardens the surface to 80-85 Rockwell C. TITANIUM NITRIDING (TiN)- provides a layer of titanium, which is applied to the tap surface with the PVD method. TiCN works particularly well in abrasive and gummy materials and in high speed, high production applications. TiCN hardens the surface to approximately 90 Rockwell C and has a lower coefficient of friction than TiN. TITANIUM CARBONITRIDE (TiCN)- is a special physical vapor deposition (PVD) coating, which includes titanium nitride. There are a number of different coatings offered to maximize tap life in your material. This means no tools are required for tap changes, reducing overall downtime! MD Technology tapping tools use a ball lock system. ![]() Still not convinced? Here is a torque comparison between a leading fastner companies product and extruding and tapping with the TT2″.
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