In the previous issue, we introduced how to improve cutting efficiency by reviewing cutting conditions such as rotation speed and feed rate.
This time, we will introduce how to improve cutting efficiency by reviewing cutting tools and machines.
The end mills used in our company for finish machining are two-flute ball end mills.
This is an end mill with two cutting edges, and we will examine whether the feed rate can be increased by increasing the number of cutting edges to 4 or 6.
Basically, finishing is performed on a 3-axis machine, but even if the same machine is used with a feed rate of 200% and 2 or 6 blades are used, the finish will deteriorate rather than improve.
Even if you change to a 2-blade machine or a 4- or 6-blade machine, the finish will not improve, but rather worsen.
The reason for this is that on a 3-axis machine, the spindle is machined vertically. The tip of the end mill is ball-shaped, so the further it goes to the tip, the more the cutting edge is lost. Also, the rotational speed decreases as you go to the tip. In other words, the cutting surface is dragged without the tool rotating.
The surface becomes rusty.
Therefore, machining with a 5-axis machine that can tilt the spindle to prevent tip machining is essential.
Furthermore, the rake angle of a 2-blade blade is often positive, while that of a 4- or 6-blade blade is negative. Therefore, a high tool speed is required for 4- or 6-blade cutting tools.
In other words, to increase cutting efficiency by increasing the number of endmill blades
(1) The machine must be a 5-axis machine that can tilt the tool to prevent tip cutting.
(2) The rake angle of the blade becomes negative, so the rotation speed must also be increased.
This can be said to be the case.
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