Обший каталог Yamawa 2016 - 2017 - страница 841

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22. Features of MC-Helical Thread Mills ■Comparison of internal threads cut by helical cutter and by PT tap Description of products ■Pipe thread cutting by tap When PT tap cuts internal threads, the tap cuts the threads with all cutting edges and the tap reverses from the position where each cutting edge on lands sticks into the material wall of internal threads. This results in the stop line due to a step caused by this sticking. ■Pipe thread cutting by helical cutter Due to the thread cutting of 3 axis movement without reversing, the internal thread has no stop line. ■Selection of tool diameter against the size of the internal threads When cutting internal threads with MC-HLC, please choose the tool which diameter is smaller than 70% of internal threads diameter. The cutter having larger outside diameter is preferable due to its high rigidity. Thread milling cutters do not have screw lead. Please select thread milling cutters by referring to product specification table to avoid poor threads caused by interference. ■Cutting Condition Carbide helical cutter HSS helical cutter Material Cutting Speed Feed per tooth (mm/t) Material Cutting Speed Feed per tooth (mm/t) (m/min) (m/min) Structural Steel 50 250 0.02 0.1 Structural Steel 25 45 0.02 0.05 Carbon Steel 50 200 0.02 0.1 Carbon Steel 20 40 0.02 0.05 Alloy Steel 30 180 0.02 0.1 Alloy Steel 15 30 0.02 0.05 Tool Steel 30 150 0.02 0.1 Tool Steel 10 15 0.02 0.04 Stainless Steel 30 200 0.03 0.1 Stainless Steel 10 15 0.03 0.05 Cast Iron 50 150 0.03 0.15 Cast Iron 30 50 0.03 0.08 Aluminum, Aluminum Alloy 50 300 0.03 0.15 Aluminum, Aluminum Alloy 50 90 0.03 0.05 Copper, Copper Alloy 50 180 0.03 0.15 Copper, Copper Alloy 40 80 0.03 0.05 ■Feed speed Feed speed is decided by the characteristic of work materials. Feed speed is an important factor because machining time, thread finish and tool Feed speed of tool durability are getting influenced by the feed speed. F = fz Z n (Dc-d)/Dc (mm/min) In the material of low tensile strength, feed per tooth can be set up rather large. However, if you set up feed per one tooth too large, thread milling fz : Feed per tooth cutters can cause deflection and may badly cause thread limit. z : Number of tooth n : Spindle RPM d : Diameter of tool Dc : Nominal size of internal thread ■Cut of cutters Side of Generally, Cut of cutter is decided by the machine programming in which internal threads the machine enables the cutter to cut the thread height in one revolution. MC helical cutter is so designed that its minor diameter does not cut, and the same bored hole size as that for cutting tap is adopted. Information Technical Side of milling cutters Technical-66 837