Grooving load large and machined surface roughness
(After the z-axis machining arrival position) from the inside to the outside when processed (set processing), after the end of the screw machining, machining inevitably become worse. Then if you do not reduce the feed rate, tool life will be shortened.

Corner of the load increases
When the processing to the outside from the inside, more acute angle corner portion machining. At this time, compared with the side processing, cutting volume will increase every turn. In order to make the cutting volume per unit time the same, it is necessary at the corners of the automatic acceleration or deceleration. The higher the hardness of the workpiece, the greater should be the magnitude of the acceleration and deceleration of the corner portion.

Extend the amount of long knives
Extending the length of the tool is too long, rigid fall, tool life will be shortened. When faced with high hardness materials or difficult to cut materials, this phenomenon will become more apparent.

Tool
Milling with an end mill, which is the plural of the cutting edge of cutting-off sequence, and some non-cutting edge from the state, with the rotation of the spindle, the workpiece contact to start cutting. The higher the hardness of the workpiece, the greater the instant impact piece tip contact, the higher the likelihood of damage to the tip. For this reason thickening tool tip, a cutting edge surface is made negative, reducing the groove portion of the blade root thicker, such a tool called a high hardness cutting tool.
However, non-high hardness with milling tool wear, for the actual processing in the vicinity of the critical diameter exhibit the phenomenon of friction, high hardness, wear with a cutter, the central portion of the front end in the actual machining diameter size range is very flat , can significantly reduce the processing time. Therefore, this factor must be included for consideration.
In summary, the use of appropriate line speed, depth of cut is reduced, as quickly as possible and with the feeding speed of the basic principle of the processing is not limited to small diameter tools.