ASME B18.29.1-2010 pdf download.Helical Coil Screw Thread Inserts— Free Running and Screw Locking (Inch Series).
1.4 Class of Fit Since helical coil inserts are flexible, the class of fit of the final assembly is a function of the size of the tapped hole. Helical coil STI taps are available for both tolerance Classes 2B and 3B tapped holes. Tolerance Class 2B tapped holes provide maximum production tolerances, but result in lower locking torques when screw locking inserts are used. The higher and more consistent torques given in Table 5 are met by the screw locking inserts when assembled and tested in tolerance Class 3B tapped holes in accordance with section 2. 1.5 Compatibility Assembled helical coil inserts will mate properly with items having UN external threads in accordance with ASME B1.1. In addition, due to the radius on the crest of the insert at the minor diameter, the assembled insert will mate with UNJ profile external threaded parts with controlled radius root threads per SAE AS8879. 1.6 Types of Inserts 1.6.1 Free-Running. The free-running insert pro- vides a smooth, hard, and free-running thread. 1.6.2 Screw-Locking. The screw-locking insert pro- vides a resilient locking thread produced by a series of chords on one or more of the insert coils. 2 STI TAPPED HOLE The tapped hole into which the insert is installed shall be in accordance with ASME B1.1, except that diameters are larger to accommodate the wire cross-section of the insert. Dimensions of the STI tapped holes are shown in Table 1 and calculated per Note (3) of Table 1. 2.1 Screw Thread Designation 2.1.1 Designation for Tapped Hole. The drawing note for the STI threaded hole per Table 1 to accept the helical coil insert shall be in accordance with the following example: EXAMPLE: 1 ⁄ 4 -20 UNC-2B STI thread 0.430 min. depth, per ASME B18.29.1. 2.1.2 Designation for a Helical Coil Insert. Designa- tion of the helical coil insert on parts lists, spares lists, purchase orders, etc., shall be in accordance with the following examples:
3.2 Properties 3.2.1 Tensile Strength. Wire, before coiling into inserts, shall have tensile strength not lower than 150,000 psi, determined in accordance with ASTM A 370. 3.2.2 Bending. Wire shall withstand, without crack- ing, bending in accordance with ASTM E 290 at room temperature through an angle of 180 deg around a diam- eter equal to twice the cross-sectional dimension of the wire in the plane of the bend. 3.2.3 Workmanship. The formed wire shall be of uniform quality and temper; smooth, clean, free from kinks, waviness, splits, cracks, laps, seams, scale, segre- gation, and other defects that may impair the serviceabil- ity of the insert. 3.3 Coatings 3.3.1 Red Dye Identification. Screw-locking inserts are dyed red for identification. The red dye may com- pletely or partially cover the insert. However, it must be sufficient to identify the insert when it is installed in the tapped hole. 3.3.2 Dry Film Lubricant Coating. When specified, dry film lubricant coating can be applied to helical coil inserts. It shall meet the requirements of para. 18.104.22.168 and para. 22.214.171.124. Color of dry film lubricated insert is dark gray to black. 126.96.36.199 Dry Film Material. The lubricant shall meet the requirements of SAE AS5272, Type I.
3.4 Configuration and Dimensions Insert configurations shall be in accordance with Fig. 1, and dimensions shall be in accordance with Tables 3 and 4. 3.4.1 Nominal Length. Each nominal insert size is standardized in five lengths which are multiples of the insert’s nominal diameter. These are 1, 1 1 ⁄ 2 , 2, 2 1 ⁄ 2 , and 3 times nominal diameter. Each nominal length is the minimum through-hole length (material thickness), without countersink, into which that insert can be installed. The nominal insert length is a reference value and cannot be measured. 3.4.2 Assembled Length. Actual assembled length of the insert equals nominal length minus 1 ⁄ 2 pitch to minus 3 ⁄ 4 pitch, with insert installed in a basic STI threaded hole. It cannot be measured in the insert’s free state. 4 INSPECTION AND QUALITY ASSURANCE Unless otherwise specified by the purchaser, the inspection of inserts shall be in accordance with ASME B18.18.2 with inspection level 3 for a 15-cycle torque test as described in para. 4.2.3. 4.1 Inspection (Nondestructive) 4.1.1 Examination of the Product. Inserts shall be visually examined for conformance with drawings and workmanship requirements in accordance with ASME B18.18.2. 4.1.2 Threads. The inserts, when assembled in STI threaded holes conforming to Table 1, shall form threads conforming to ASME B1.1, tolerance Class 3B or Class 2B except for the locking feature of screw-locking inserts. The assembled insert, both types, shall accept and function with parts having external UNJ threads per SAE AS8879. NOTE: Accuracy of the finished thread, when the insert is installed, is dependent upon the accuracy of the tapped hole. If the finished tapped hole gages satisfactorily, the installed insert will be within the thread tolerance when the insert meets the requirements of the Standard. It is, therefore, not necessary to gage the installed insert.