Threading Technology – Clamping Technology 520

209 Roll Form Taps UNC UNF M MF G STI SELF-LOCK Tech. Info v c Product Finder The recommended preparatory diameters enable a cold-formed minor diameter of the thread within tolerance (for M and MF according to DIN 13-50). Preconditions include a stable clamping of tool and workpiece as well as solid carbide twist drills which are new or as good as new. In order to optimize tool life, larger thread hole preparatory diameters may be used. But it is necessary to ensure that the minor diameter of the thread complies with the tolerance (for M and MF according to DIN 13-50). We recommend a smaller preparatory diameter by 0.05 mm respectively 0.002 in for difficult to form materials (such as aluminum cast alloys) for P ≥ 1 mm respectively from 24 T.P.I. The recommended preparatory diameters were carefully determined and tested in the field. In rare cases it may happen that the recommended preparatory diameters do not provide the desired minor diameter of the internal thread. In such cases the suitable preparatory diameters must be determined in tests. 2.17 Recommended tap drill sizes for cold-forming internal threads STI-UNC Unified coarse thread ASME B18.29.1 For wire thread inserts Nominal Size D 1 (2B) Rec. tap drill size P [T.P.I.] min. max. STI-No. 2 56 0.1004 0.1016 0.1004 STI-No. 4 40 0.1323 0.1339 0.1327 STI-No. 6 32 0.1630 0.1646 0.1634 STI-No. 8 32 0.1894 0.1921 0.1909 STI-No. 10 24 0.2228 0.2256 0.2244 STI 1 / 4 20 0.2894 0.2929 0.2913 STI 5 / 16 18 0.3563 0.3598 0.3583 STI 3 / 8 16 0.4240 0.4287 0.4272 STI 7 / 16 14 0.4933 0.4976 0.4961 STI 1 / 2 13 0.5602 0.5646 0.5630 STI-UNF Unified fine thread ASME B18.29.1 For wire thread inserts Nominal Size D 1 (2B) Rec. tap drill size P [T.P.I.] min. max. STI-No. 4 48 0.1291 0.1311 0.1299 STI-No. 6 40 0.1583 0.1606 0.1594 STI-No. 8 36 0.1866 0.1882 0.1870 STI-No. 10 32 0.2150 0.2177 0.2165 STI 1 / 4 28 0.2783 0.2811 0.2795 STI 5 / 16 24 0.3457 0.3480 0.3465 STI 3 / 8 24 0.4083 0.4110 0.4094 STI 7 / 16 20 0.4772 0.4799 0.4783 STI 1 / 2 20 0.5398 0.5429 0.5413 Screw Thread Insert Threads (STI) 60° D 1STI D STI P LK-UNC Unified SELF-LOCK coarse thread EMUGE standard Nominal Size D 1 Rec. tap drill size D P [T.P.I.] min. max. LK No. 4 40 0.1035 0.1055 0.1043 LK No. 6 32 0.1280 0.1303 0.1280 LK No. 8 32 0.1539 0.1563 0.1555 LK No. 10 24 0.1752 0.1783 0.1772 LK No. 12 24 0.2012 0.2047 0.2028 LK 1 / 4 20 0.2315 0.2354 0.2323 LK 5 / 16 18 0.2913 0.2961 0.2933 LK 3 / 8 16 0.3508 0.3559 0.3524 LK 7 / 16 14 0.4091 0.4146 0.4094 LK 1 / 2 13 0.4689 0.4752 0.4724 LK-UNF Unified SELF-LOCK fine thread EMUGE standard Nominal Size D 1 Rec. tap drill size D P [T.P.I.] min. max. LK No. 4 48 0.1047 0.1067 0.1055 LK No. 6 40 0.1295 0.1315 0.1299 LK No. 8 36 0.1543 0.1567 0.1555 LK No. 10 32 0.1799 0.1823 0.1811 LK 1 / 4 28 0.2382 0.2409 0.2382 LK 5 / 16 24 0.2980 0.3016 0.2992 LK 3 / 8 24 0.3606 0.3638 0.3622 LK 7 / 16 20 0.4193 0.4232 0.4213 LK 1 / 2 20 0.4819 0.4858 0.4843 Self-Locking Threads D 1 D 1 P BT P ≥ 36 T.P.I. (P ≤ 0.7 mm) 60° D P 90° 60° 30° D LK-M Metric SELF-LOCK coarse thread EMUGE standard Nominal Size D 1 Rec. tap drill size D P [mm] min. [mm] max. [mm] [mm] [inch] LK-M 3 0.5 2.82 2.88 2.85 0.1122 LK-M 4 0.7 3.77 3.83 3.8 0.1496 LK-M 5 0.8 4.77 4.83 4.8 0.1890 LK-M 6 1 5.7 5.78 5.7 0.2244 LK-M 8 1.25 7.58 7.68 7.6 0.2992 LK-M 10 1.5 9.48 9.58 9.5 0.3740