Обший каталог Yamawa 2016 - 2017 - страница 841

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21. 22. Features of MC-Helical Thread Mills 22.

■Comparison of internal threads cut by helical cutter and by PT tap

■Pipe thread cutting by tap

When PT tap cuts internal threads, the tap cuts the threads with all cutting edges and the Number of threads 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

MaterialCutting Speed (m/min)Feed per tooth (mm/t)
Structural Steel50�2500.02�0.1�
Carbon Steel50�2000.02�0.1�
Alloy Steel30�1800.02�0.1�
Tool Steel30�1500.02�0.1�
Stainless Steel30�2000.03�0.1�
Cast Iron50�1500.03�0.15
Aluminum, Aluminum Alloy50�3000.03�0.15
Copper, Copper Alloy50�1800.03�0.15
MaterialCutting Speed (m/min)Feed per tooth (mm/t)
Structural Steel25�450.02�0.05
Carbon Steel20�400.02�0.05
Alloy Steel15�300.02�0.05
Tool Steel10�150.02�0.04
Stainless Steel10�150.03�0.05
Cast Iron30�500.03�0.08
Aluminum, Aluminum Alloy50�900.03�0.05
Copper, Copper Alloy40�800.03�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 durability are getting influenced by the feed speed. 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 cutters can cause deflection and may badly cause thread limit.

■Cut of cutters

Generally, Cut of cutter is decided by the machine programming in which 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.

Feed speed of tool

F=fzZn Dc-d)/Dc (mm/min)

fz : Feed per tooth z : Number of tooth n : Spindle RPM d : Diameter of tool Dc : Nominal size of internal thread

Side of internal threads

Side of milling cutters