Threading Technology – Clamping Technology 520

639 Tap Holders Soft- synchro Speed- synchro KSN MQL SFM HF EM Accessories Tech. Info Product Finder 7.4 Rigid tapping 2. Influencing factors by the threading tool a) Tolerances of the thread pitch For threading tools the European standard DIN EN 22857 defines the dimensions and tolerances for ground threads. For the tool tolerance the standard allows a smallest deviation of ± 8 µm referred to a defined number of threads. Example: Tap M10 Thread pitch 1.5 mm Check length 7 threads P Allowed pitch tolerance ± 8 µm 0 2 4 6 8 10 12 14 16 18 20 0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 Force/Movement graph Required force for the length change of threading tool with shank diameter 10 mm Force [N] Length change [µm] Thread standard-conditional pitch fault acc. to DIN EN 22857 Thread pitch P = 1.5 mm b) Change of thread pitch and length of the threading tool when t Work ≠ t Measurement Each tool temperature – differing from the measuring temperature 20°C – causes a change in length. For an M10 tap with 100 mm length the temperature change from 20 °C to e.g. 40 °C causes a length change of 32 µm. Considering a check length of 7 threads acc. to standard DIN EN 22857 the following example results: Tap M10 Thread pitch 1.5 mm Tap length 100 mm Check length 7 threads = 10.5 P Axial growth of the tool and thread pitch of 3.4 µm 20 25 30 35 40 45 100.000 100.005 100.010 100.015 100.020 100.025 100.030 100.035 100.040 100.045 Temperature change development of a threading tool M10 Length 100 mm, temperature change 20 °C, length change 32 µm Tool length [mm] Temperature [°C] Length change of a threading tool M10 Referred to a check length of 7 threads acc. to DIN EN 22857 and a pitch of 1.5 mm the axial length would change by 3.4 µm . The proof of a change in temperature of the threading tool can be given by measuring the cutting face being heaviest used during the thread production. The following graph shows the temperature of the cutting face for a threading tool M10 with various cutting speeds. Material used is 1045, coolant-lubricant is 5% emulsion. 0 10 20 30 40 50 60 70 80 90 0 50 100 150 200 250 300 Temperature progressing on the tool tooth face (M10), emulsion as coolant-lubricant Tooth face temperature t sp [°C] Cutting speed v c [m/min] Material 1045