Threading Technology – Clamping Technology 520

470 Thread Gages UNC UNF UNS M MF Rp, R, Rc NPT NPTF STI SELF-LOCK G (BSP) Product Finder Smooth GT, TD Accessories Calibration Tech. Info G-GUT-LD • The GO thread plug gage checks the so-called “mating size” of the internal thread and the screwing-in capability. In doing so, it checks the smallest size of the internal thread pitch diameter D 2 including certain form deviations in the thread, e.g. pitch and thread profile angle deviations. It also checks the smallest size of the major diameter. The minor diameter D 1 of the internal thread is not checked. • The GO thread plug gage must be able to be screwed by hand into the full length of the workpiece thread without using particular force. The permissible wear of the GO thread plug gage is determined by measurement based on the three-wire-method. The GO thread plug gage is subject to heavy wear and should be checked at regular intervals. EMUGE therefore recommends using GO thread plug gages in the hard-chrome-plated or coated version. • Dimensions of the GO thread plug gage acc. DIN 2281 and DIN 2282. • The GO thread plug gage has a full thread profile along its thread length. It should be noted that the thread length is not less than 80% of the screw-in length of the workpiece thread. GO thread plug gages, starting from a thread diameter of 5.5 mm, are provided by EMUGE with a dirt flute. • According to DIN ISO 1502, no so-called “acceptance” GO plug gages are standardized. • It is advisable to always use the new plug gages for production and keep those that are close to the wear limit for acceptance. G-AUS-LD NO-GO thread plug gage • The NO-GO thread plug gage checks whether the actual pitch diameter of the workpiece internal thread exceeds the prescribed largest size. The internal thread major diameter and internal thread minor diameter are not checked. • It must not be possible to screw the NO-GO thread plug gage into the workpiece thread by hand for more than two revolutions (from both sides) without the use of particular force. The two revolutions are determined on screwing out the plug gage. • The NO-GO thread plug gage has a thread length of at least three threads. The thread profile has a truncated crest. • The gages are marked with a red coloured ring. • Dimensions acc. DIN 2283 and DIN 2284. G-GR-LD GO/NO-GO thread plug gage • The GO/NO-GO thread plug gage is the combination of a GO thread plug gage and a NO-GO thread plug gage on one handle. • The dimensions of the GO/NO-GO thread plug gages are specified up to a nominal dimension diameter of 40 mm in DIN 2280. The functionality corresponds to the GO and NO-GO thread plug gages previously described. Glatt-GR-LD Gages for the internal thread minor diameter • The internal thread minor diameter D 1 is checked with a smooth, cylindrical GO and NO-GO plug gage or a GO/NO-GO plug gage. As the minor diameter can change through thread tapping, an inspection is required after the thread has been completed. Specific gages are available to check the extended minor diameter tolerance of cold-formed Metric internal threads. Basically, the internal thread minor diameter should be checked before gaging the internal thread pitch diameter. • It must be possible to guide the smooth GO plug gage by hand through the workpiece thread without the use of particular force. • It must not be possible to insert the smooth NO-GO plug gage into the workpiece thread from both sides deeper than one pitch (1 x P) from the start of the thread. 6.4 Thread gages for internal threads and smooth gages for thread minor diameters The GO thread plug gage and the NO-GO thread plug gage are used for the gaging of internal threads. GO and NO-GO plug gages are mounted on a common handle for thread diameters up to 40 mm and are designated as GO/NO-GO thread plug gages. For exceptional cases handles for GO/NO-GO thread plug gages up to a thread diameter of 62 mm are standardized in DIN 2240-2. A (smooth) GO and NO-GO plug gage is recommended for gaging the internal thread minor diameter.