Self tapping screw with drill tail thread: inspection requirements
1. Heart hardness: standard value hrc28-38. The test is carried out on the section 1-2 times the diameter from the tail. If the length of the title is too short, it can be embedded first, and then the hardness can be measured.
2. Surface hardness: Standard min hv450.
3. Carburized layer: Standard 4##-6#:0.05-0.18mm, 8#-12#:0.10-0.23 mm, 14#:0.13-0.28 mm. The main purpose of carburization is to enhance the surface hardness and ensure the strength of teeth. If decarburization is too deep and carburization is insufficient, the strength of teeth will not meet the requirements, that is, when doing the screw in test, the teeth will be damaged.
4. Torque: Standard Specification 4 \5 \6 \7 \8 \10 \12 \14 \a tooth 1421283556596145ab tooth 142128354565102165.
5. Screw in test: screw the self tapping screw into a steel plate with a reserved test hole. The self tapping screw should form a matching thread in the test plate, and the thread of the screw itself will not be deformed and damaged until the end taper thread completely passes the test plate. Screw in test is only applicable to AB, B, BP and other types of self tapping screws. IFI stipulates that the test plate shall be made of semi-rigid low-carbon cold rolled steel, and the hardness of the steel plate is Rockwell 70 – 85hrb. See the following table for the standard specification of steel plate, i.e. thickness. The test hole should be punched or drilled, and the tolerance is ± 0.025mm of the specified nominal diameter (see the table below). Specification 6 \7\8\10\12\1/4 test plate thickness (mm) 1.85-1.953.12-3.234.68-4.84 aperture (mm) ± 0.0252.953.263.454.044.765.50