made from high speed steels or with carbides inserts, similar with face milling. The milling cutter basically rotates on an axis perpendicular to the work pieces surface during
machining, and it’s also can be tilted to conform machine tapered or curves surfaces. Based on previous researches Saedon et al. 2012. Saedon et al. 2012, Material
deposited onto the cutting edges and on the end face of the tool will have a direct influence on cutting forces and work piece surface roughness.
2.3 END MILL CUTTER
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Figure 2.1 End mill tool
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Figure 2.2 End mill tool inserts Palbit cutting tool supplier
The end mill cutter can be divided into two parts which are solid end mills and inserted end mill. The figure 2.1 show the milling tool holder for insert end mill is made from a
hardened material and the figure 2.2 show the end inserted end mill cutter, when the tips inserted will be change if the tips have a bad sharpens. The material of inserts is made
from physical vapour deposition PVD Titanium Aluminum Nitride TiAlN. Based on research by Koshy et al. 2002, TiAlN coated carbide tools were suitable, with the tool
life being dependent primarily on the cutting speed. According to López de Lacalle et al. 2002, Coated tools are specially suited to those situations in which an improvement of
abrasive wear resistance, a reduction of chemical affinity between workpiece material and tool material or an improvement in friction conditions is required. Thus in order to
enhance machining capability of carbide cutting tools, they are normally coated with single or multi-layers of hard, wear resistant TiN, TiCN and TiAlN coatings by chemical
vapour deposition CVD or physical vapour deposition PVD techniques Prengel et al., 2001. The tool performance is of the factors that influencing the quality of surface
roughness.
2.4 MACHINING PARAMETERS
In getting the best result in milling operations, the parameter have to be specifying in term of cutting speed, feed rate, and depth of cut. Based on Alauddin et al. 1997, with increase
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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.
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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.
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Figure 2.3 Cutting parameter of end mill
2.4.4 WIDTH OF CUT
Width of cut, ae mm can be described as the paths of cutting tool moving along the workpiece surface, see the figure 2.3. Basically the width of cut is less than the cutter
radius. The cutter is only partially engaged and making a peripheral cut during milling operations. A highest width of cut will require a lowest feed rate. The result in a highest
width of cut will affected tool and reduce the tool life Zhang et al., 2012.
2.5 AISI D2 TOOL STEEL
The material of AISI D2 tool steel is belonging in the high carbon contains group. D2 tool steel has excellent wear and abrasion resistance, due to large quantities of carbides in the
microstructure. This material is broadly used in cold work process application that requiring very high wears resistance and high compression strength. For machining
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process, tool steel basically machined in the annealed condition in to exhibits minimal distortion in heat treat. Tool steel material is available in round, flats and squares, flat
stock and drill rod. According to Bourithis et al. 2006, the research was conducted is analyze the wear characteristics of two commercial tool steels which are AISI D2 and O1.
The both of this material with have the same hardness of 60 HRC tested by using pin-on- disk. From the result obtained, the tool steel microstructure is important role to determine
the wear properties of their material. Tool steels materials basically used in application of high temperature, resistant to wear, cutting tool, and mould applications Bourithis et al.,
2006. Based on Budinski 1992, the tool steel material can be classified into six categories which is: cold work, shock resisting, hot work, high speed, mold and special-
purpose tool steels. Among of this material, cold work tool steels are very important part, as they are widely used for making of tool and dies. Other than that, applications that need
high wear resistance and low cost is most suitable for this material, Glaeser 1992. In general by, Budinski 1992 various tool steels basically fulfil the requirements for a
given application, so that final choose is guided by considering the tool life as well as the cost of material and fabrication.
2.6 CUTTING TOOL PERFORMANCE
