As the name suggests, a ball nose milling cutter is a milling cutter with a spherical head. Ball nose cutters can be divided into two types: roughing ball nose cutters and finishing ball nose cutters.
From a structural point of view, indexable ball nose milling cutters, exchangeable head indexable ball nose milling cutters, solid carbide ball nose milling cutters, and exchangeable head carbide ball nose milling cutters are all optional, as shown in Figure 5-5.
The two indexable ball nose cutters shown in Figure 5-5 are similar to the lap teeth of indexable corn cutters. The first from the left is a full-tooth ball nose cutter with side teeth, which can also be said to be a corn milling cutter with ball head, and the insert on one of the flutes can be fully connected axially to complete the complete cut from the first insert to the last insert (but when there are multiple flutes, there will generally only be one insert with a center on the flute). The third from the left is a misaligned tooth structure, with a gap between two adjacent curved trilateral inserts, which requires an identical curved trilateral insert on the other flute to complete the rest of the cutting tasks. The end teeth of a ball nose cutter are a complete hemispherical shape, while the third one on the left side of Figure 5-5 is in the form of a circular arc that exceeds a hemisphere. This cross-hemisphere ball nose cutter can be used for so-called back milling with the back teeth, as shown in Figure 5-6. The second structure of the indexable ball nose milling cutter is that the entire ball head part is completed by a blade, and no lap is made, because because the blade always has manufacturing errors, the arc formed by lap will always have some traces of the cutter, and the whole arc is completed by a blade is based on this consideration. Figure 5-7 shows one such milling cutter, also commonly referred to as the lancet milling cutter F2339, because the inserts of this type of milling cutter often take the shape of a willow leaf. The arc value of the willow leaf ball nose milling cutter is not very accurate, but it is still sufficient for the processing of most plastic molds. For ball nose cutters that require higher precision, the third indexable ball nose cutter or solid carbide ball nose cutter described below can be used.
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The third indexable ball nose cutter is a single-insert indexable ball nose cutter, as shown in Figure 5-8. This type of ball nose milling cutter generally has a high insert accuracy, and both cutting edges can be cut through the center. This type of milling cutter is available from many tool manufacturers, but the positioning of the insert and shank is not the same.
Solid carbide ball nose milling cutters and replacement head carbide ball nose milling cutters generally have 2~4 teeth. The second from the left in Figure 5-5 is a 2-tooth solid carbide ball nose cutter, while the fourth from the left in Figure 5-5 is a 4-tooth exchangeable head ball nose cutter. The 4-tooth ball nose cutter is smaller than the 2-tooth ball nose cutter and has a strong chip groove, which is suitable for the machining of existing cavities, while the 2-tooth ball nose cutter is more suitable for machining the cavity directly on the body.
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