Purpose of test
A cBN radius end mill was tested for slot machining in hard materials, which is a difficult process with conventional carbide end mills due to their machining inefficiency and limited tool life.
|Cutting fluid||Oil mist|
|Tool used||cBN radius end mill (φ1 × R 0.1 × 6 (effective length)), manufactured by Kyowa|
Cut slots 1 mm wide by 6 mm deep in a block measuring 80×60×30 mm, followed by visual evaluation at 200× magnification.
|Spindle rotational frequency||：18,000rpm（56.5m/min）|
|Cutting||:10 μm × 600 strokes per slot|
|Cutting length||:80 mm × 600 strokes = 48000 mm (48 m) per slot|
|Machining time||:1 h 42 min per slot|
A cBN radius end mill was able to cut ten slots 1 mm wide by 6 mm deep by 80 mm long in a hard material. However, beginning with the fifth slot, traces of wear or chipping can be seen at the corners. The total cutting length attempted in this test was 48 mm × 10 slots = 480 mm, but a practical length is 48 mm × 4 slots = 192 mm. (Only one slot can be cut with a carbide end mill.) However, increasing the cutting speed (1.5 to 2 times faster) would provide more favorable conditions.
|Table 1 Cutting conditions|
|Axial depth of cut||20μm|
|Rotation rate||20000rpm, 40000rpm, 60000rpm|
|Effects of rotational frequency and cutting oil on machined surfaces|
|Rotational frequency||Machined edge||Machined surface|