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
Basically cutting tool performance can be described as the ability of tool to maintain a stable condition in term of strength, hardness, and thermal resistance. Based on the
previous research by Alauddin et al. 1997, the cutting tool deteriorate are due to the edge fracture and plastic deformation. Other researcher Becze et al. 2000 found that complex
tool path also affect the tools wear. Based on the figure 2.4, it can be seen that the fracture occur at the end of the tool insert.
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The factors that cause the fracture are cutting speed, width of cut, and depth of cut. Other than that based on the research by Koshy et al. 2002, flank wear are caused by chipping,
adhesion and attrition during milling process.
Figure 2.4: Edge fracture
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Figure 2.5: A typical flank wear pattern observed on the solid carbide cutter Koshy et al., 2002
The figure 2.5 is show a typical flank wear occur on solid carbide tool. According to research done by Alauddin et al. 1997, found that an increased in the speed, the feed
rate, and the axial depth of cut, it will decreased tool life. The figure 2.6 show the adhesion between the chip and the cutting edge at the maximum chip load location, were strong
enough to support chips adhering to each other during the cutting Koshy et al., 2002.
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Figure 2.6 Chip during material removal due to adhesion Koshy et al., 2002
Based on Koshy et al. 2002 also the large volume of high-hardness undissolved chromium carbide particles in the D2 that are responsible for imparting good wear
resistance to the material, also promote attritions wear of cutting tools and renders the material extremely difficult to machine.
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2.7 SURFACE ROUGHNESS
Surface roughness is defined as the surface irregularities which result from the several of machining conditions. These irregularities mean that the surfaces are combining to form
surface texture. Surface roughness has proportion influences on product quality. Moreover a good quality of surface roughness obtain from the machining is significantly improves
fatigue strength, corrosion resistance and creep life of the part. Other than that, the quality of surface roughness also affect several function of part or products such as contact
causing surface friction, wearing, light reflection, heat transmission, ability of distributing and holding a lubricant, coating, or resistance fatigue Lou et al., 1998. Profile of surface
roughness and waviness are shown in figure 2.7
Figure 2.7: roughness and waviness profiles Lou et al., 1998
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In machining process, the common parameters that affect the surface roughness are cutting speed, feed rate, and type of lubricant, depth of cut and width of cut. Based on Liao et al.
2007, the milling parameters of feed rate and lubricating method have significant affected on quality of surface roughness and they discover that the quality of surface
roughness increased by increased the feed rate. There are several factors that contradict the feed rate in affecting the surface roughness where high cutting speed will reduced the
value of surface roughness. The previous research by Ozcelik and Bayramoglu 2006, the cutting parameter is the important part in producing a minimum surface roughness and
long tool life. the minimum surface roughness was obtained when the cutting parameters was set at the lowest of feed rate and highest of cutting speed Özel et al., 2007. The
differences of machining process parameters will impact the quality and specifications of the products surface. At the same time the result of the higher surface roughness can affect
the product performance in terms of friction, durability, operating noise, and energy consumption.
2.8 SURFACE FINISH PARAMETERS
