Study of the machinability of compacted graphite iron for drilling process

Mocellin, F.; Melleras, E.; Guesser, Wilson Luiz; Boehs, Lourival

doi:10.1590/s1678-58782004000100004

Cited by 36 publications

(24 citation statements)

References 1 publication

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“…The CGI alloys have good properties of mechanical strength, ductility, toughness, thermal shocks, damping and heat conductivity (Mocellin et al, 2004). These properties are better for the CGI part functioning, but make its machinability worse than the machinability of GCI.…”

Section: Compact Graphite Iron -Cgimentioning

confidence: 99%

Performance of carbide and ceramic tools in the milling of compact graphite iron - CGI

Gabaldo¹,

Diniz²,

Andrade³

et al. 2010

J. Braz. Soc. Mech. Sci. & Eng.

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Grey cast iron (GCI) is the most common material used in diesel engineCompact graphite iron is a material with intermediary properties between grey cast iron (GCI) and ductile cast iron (Sahm et al., 2002). Like in the GCI, the graphite particles in the CGI are flat, long, randomly oriented and interconnected. In the ductile iron they are in form of nodules (Warrick et al., 1999). However, as it can be seen in Fig. 1(b), the "worms" (as the graphite particles in the CGI are called) have something in common with the nodules of the ductile iron ( Fig. 1(a)), since both are much smaller than the graphite lamellas of the GCI (Fig. 1(c)). On the other hand, the morphology of CGI graphites is compact and with rounded tips, what makes the nucleation and growth of cracks more difficult than in the GCI. The sharp and lamellar graphites of the GCI with smooth surfaces (Fig. 1(c)) make this material more fragile than the other two (Löhe, 2005).The CGI alloys have good properties of mechanical strength, ductility, toughness, thermal shocks, damping and heat conductivity (Mocellin et al., 2004). These properties are better for the CGI part functioning, but make its machinability worse than the machinability of GCI.Compared with GCI, the CGI presents some advantages like reduction of the wall thickness of the parts for a same load, reduction of the safety factor due to a smaller variation of the cast properties, reduction of the fragile fractures during manufacturing, assembly and service due to its higher ductility and strength (Dawson, 1999).Compared with ductile cast iron, it can be said that with CGI it is easier to produce complex cast parts and the residual stresses are smaller due to the higher heat conductivity (what also helps to increase cutting tool life). Moreover, it presents smaller Young modulus and better machinability (Guesser, 2004). Milling of CGI engine blocksBesides the worm graphite particles, a certain percentage of spheroidal graphite nodules is also present in the CGI. As the nodularity increases, the material strenght also increases making the forces needed to cut the material higher. Moreover, with the nodularity growth, the heat conductivity decreases, decreasing machinabilty even more (Dawson, 2002).A factor that makes the engine blocks even more difficult to be machined is the great number of interruptions on the surface. Special care has to be taken in the mill cutter choice, because very positive tools reduce cutting force, but may generate tool life relatively lower when compared to the cutters with negative geometry, due to their small impact resistance.As the tool wears, workpiece surface roughness and flatness error increase. Besides tool wear, other important factors to obtain J. of the Braz. Soc. of Mech. Sci. & Eng.

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Section: Compact Graphite Iron -Cgimentioning

confidence: 99%

Performance of carbide and ceramic tools in the milling of compact graphite iron - CGI

Gabaldo¹,

Diniz²,

Andrade³

et al. 2010

J. Braz. Soc. Mech. Sci. & Eng.

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“…The better mechanical properties of CGI originate from its graphite structure and shape, which are vermicular or worm-shaped and randomly oriented. However, the main problem that has prevented this material from being widely used is its poor machinability [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Cutting Performance of Low Stress Thick TiAlN PVD Coatings during Machining of Compacted Graphite Cast Iron (CGI)

et al. 2018

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Abstract:A new family of physical vapor deposited (PVD) coatings is presented in this paper. These coatings are deposited by a superfine cathode (SFC) using the arc method. They combine a smooth surface, high hardness, and low residual stresses. This allows the production of PVD coatings as thick as 15 µm. In some applications, in particular for machining of such hard to cut material as compacted graphite iron (CGI), such coatings have shown better tool life compared to the conventional PVD coatings that have a lower thickness in the range of up to 5 µm. Finite element modeling of the temperature/stress profiles was done for the SFC coatings to present the temperature/stress profiles during cutting. Comprehensive characterization of the coatings was performed using XRD, TEM, SEM/EDS studies, nano-hardness, nano-impact measurements, and residual stress measurements. Application of the coating with this set of characteristics reduces the intensity of buildup edge formation during turning of CGI, leading to longer tool life. Optimization of the TiAlN-based coatings composition (Ti/Al ratio), architecture (mono vs. multilayer), and thickness were performed. Application of the optimized coating resulted in a 40-60% improvement in the cutting tool life under finishing turning of CGI.

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“…In the case of engine manufacturing, the most critical cutting operations are cylinder honing and boring. 6 Tapping operation is also a key cutting process in engine cylinder block manufacturing, although there are little information available on this process.…”

Section: Introductionmentioning

confidence: 99%

Tool wear when tapping operation of compacted graphite iron

Mota¹,

Reis

Machado

et al. 2013

Proceedings of the Institution of Mechanical Engineers, Part B:

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The automotive industry has made increasing use of compacted graphite iron in the manufacture of several components traditionally made of gray iron. However, in some cases, the poor machinability of compacted graphite iron compared to that of gray iron renders production costs uncompetitive. Several researches have focused on the machinability of compacted graphite iron, particularly in turning, milling and drilling operations. However, tapping, which is a more complex operation, has received little attention. The main objective of this work is to investigate the performance of cemented carbide taps when tapping ASTM A450 compacted graphite iron using TiAlN-coated M13 3 1.5 taps with four straight flutes. Cutting tools with different wear levels were analyzed after their use in machining engine cylinder blocks. Tool wear was measured and analyzed using scanning electron microscopy and optical microscopy. The main wear mechanisms observed were adhesion and abrasion.

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Study of the machinability of compacted graphite iron for drilling process

Abstract: CGI -Compacted Graphite

Cited by 36 publications

References 1 publication

Performance of carbide and ceramic tools in the milling of compact graphite iron - CGI

Performance of carbide and ceramic tools in the milling of compact graphite iron - CGI

Cutting Performance of Low Stress Thick TiAlN PVD Coatings during Machining of Compacted Graphite Cast Iron (CGI)

Tool wear when tapping operation of compacted graphite iron

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