in the cutting speed of machining, the feed, and the depth of cut it will simultaneously decrease the life of cutting tool during machining operation.
There have several factors also affect the tool life during machining which is type of lubricant, cutting forces, and type of tool material. According to Zhang et al. 2012, the
tool life under minimum quantity lubricants MQL the cutting condition is using the
cryogenic compressed air and the micro droplets of the biodegradable vegetable oil increase the tool life and the tool wear significantly. In their research, it is found that the
lower cutting forces under Minimum Quantity Lubricants, the cutting condition has relatively slight tool wear due to its superior cooling and lubrication performances. Based
on two finding above, tool life will increase when feed rate is decrease. Other factors that may increase the tool life are speed, types of lubricant and dept of cut.
2.4.1 CUTTING SPEED
Cutting speed, Vc mmin is defined as the surface speed at diameter of the cutter rotating moving past a work piece. Based on Liao et al. 2007, the cutting force of milling
operation will decrease slightly to the cutting speed is increase. Through the research by Özel et al. 2007, the parameters which are cutting speed, feed rate, depth of cut and the
radius of tool nose which significantly influence the effect of surface roughness.
Equation 1.1
Based on equation 2.1, where D is diameter mm of cutter and N refers to the spindle speed revmin.
12
2.4.2 FEED RATE
Feed rate, Fz mmtooth is the distance, that the tool is moving or “fed”, through the work piece makes finish one revolution, divided by the number of effective cutting edges on the
tool. Based on Özel et al. 2007, at the lowest feed rate and the highest cutting speed it will produce the best of surface roughness. From the equation 2.2, generally the unit of
feed rate is given in mmtooth.
�� =
� ��
������ℎ Equation 2.2
Where v is the linear speed of the work piece or feed rate, mmmin and n is the number of teeth on the tool.
2.4.3 DEPTH OF CUT
Depth of cut, ap mm is a depth of cutting tool move down vertically to machining the thickness of material by one pass revolution of the cutting tool. According to Ozcelik and
Bayramoglu 2006, the cutting parameters consists of feed rate, depth of cut and cutting speed is influencing on the surface roughness. Depth of cut basically is related to the
efficiency of the cutting process. The deeper of the cutting process will affected the production rate. The rate of cutting is depends on the strength of the cutter and the material
to be cut. For a certain cutter typically the range of cut will be recommended by the supplier. However a finer cut is usually associated with a better surface and for a long tool
life. The figure 2.3 show machining operation against the work piece related to the milling parameters.
13
Figure 2.3 Cutting parameter of end mill
2.4.4 WIDTH OF CUT
