Flat end mill is the end mill with flat/square end. It is a general end type for rough milling,more economic compared with ball end mill and corner radius end mill, but it is not suitable for machining in speed as high as other two type end mills because too high rotation and feed rate may cause sharp corner blade to break.
There are four carbide grades applied to general flat end mills:
BT45, for milling materials of which hardness range from HRC45degree to HRC48degree, workpiece categories P, K, and softer stainless steel under M group in ISO classification.
BT50, for HRC50 to HRC53degree, mainly for M, N, and K group workpiece.
BT55, for HRC55 to HRC58degree, for S, M, and K workpiece.
BT60, for HRC 60 to 65degree, for milling quenched materials (HRC65 about), hardwood, and finish milling of SUS 316L stainless steel, most workpiece under ISO category H.