Now showing 1 - 9 of 9
  • Publication
    Tribological Behaviour of Graphene Nanoparticles as an Additive in Vegetable Based Oil
    ( 2024-04-19)
    Noor N.Z.M.
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    ;
    Zain M.Z.M.
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    Friction between cutting tool and workpiece generates heat, which can shorten tool life and impair the quality of machined parts. Thus, the use of appropriate lubricants is required to mitigate these issues. In this research, the use of different weight concentration of graphene nanoparticles (0.1 %, 0.5 % and 1.0 %) to augment commercially available vegetable-based oil, LB3000 was investigated using tribological test. Their performances were evaluated in form of the coefficient of friction, wear scar diameter, kinematic viscosity and thermal conductivity. Higher concentration of graphene was found to be more effective in terms of lowering coefficients of friction, reducing wear scar diameter, and improving kinematic viscosity and thermal conductivity. This study clearly demonstrates that a suitable combination of graphene nanoparticles in oil can improve tribological behaviour as well as lubrication performance.
  • Publication
    Machining of Cobalt Chromium Molybdenum (CoCrMo) Alloys: A Review
    ( 2021-01-01)
    Saravanan R.
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    Murad N.M.
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    Cobalt chromium molybdenum (CoCrMo) alloys are not only broadly applied in engineering fields but also in manufacturing of surgical implants components and medical devices due to its outstanding properties of wear resistance and great biocompatibility as demanding in the vivo environment. However, these alloys classified as difficult to cut materials as it presents several characteristics such as high hardness, low thermal conductivity, high wear resistance and strain hardening which contribute to its poor machinability. Although these CoCrMo alloys are theoretically similar to titanium alloy in terms of properties but the studies on machining of CoCrMo alloys still insufficient. This paper provides a review on machining aspects of cobalt chromium molybdenum (CoCrMo) alloys including the properties and machinability, cutting fluid methods and tool material selection for these alloys.
      7  33
  • Publication
    Effect of Inclined Angle in Trimming of Ultra-high Strength Steel Sheets Having Inclined and Curved Shapes
    Trimming the scrap portion of ultra-high strength steel (UHSS) components poses a significant challenge due to the inherent high strength and hardness characteristics of the material. For UHSS components with a higher geometric complexity such consisting of inclined and curved sections, sharp tilt, and small bend radius, the large trimming load results in poor sheared quality and shape defects, which commonly happen in these areas. This research investigated the effects of applying a small inclination angle to the punch in the trimming of the UHSS parts having an inclined and curved shape. The inclined punch was modified to four sets of different degrees of inclination i.e., 1°, 3°, 5°, and 10°. A comparative analysis of the trimming load, trimming energy, sheared edge quality and shape defects was conducted between these modified punches and the normal punch for their effectiveness in the trimming operation. Results showed that the application of inclination angle significantly decreased the trimming load, reduced the trimming energy, and improved the sheared edge surface quality, as well as prevented the shape defects at the inclined and curved zones as compared to the outcomes produced when trimming using the normal punch. The study suggested that the change to the punch geometry is an effective option to improve the performance of the process as well as the quality of the part, particularly in trimming the high-strength components having complex shapes.
      4  42
  • Publication
    Effect of cutting environment and swept angle selection in milling operation
    ( 2021-12-01) ;
    Rusli N.S.N.
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    Cutting fluids are frequently aimed to enhance machinability through cooling, lubricating and flushing actions. However, their use in machining creates major concerns in terms of health footprint and environmental effects throughout their lifecycle. Alternative methods, such as dry cutting and minimum quantity lubrication, were used to mitigate these issues. This research also will investigate the effect of swept angle selection, 30% and 60% of tool diameter step over under different cutting conditions during milling of aluminium alloy material. Their impact on tool wear, surface roughness, burr and chip formation were compared. Results pointed that the application of lower swept angle in conjunction with minimum quantity lubricant system has significantly reduced tool wear, decreased burr and chip formation, as well as improved surface quality as compared to dry machining. The work clearly shows how the importance of swept angle selection and cutting condition in refining machining performance could improve the machinability of the material.
      29  2
  • Publication
    Effect of Different Cutting Conditions on Tool Wear and Chip Formation in Drilling of Cobalt Chromium Molybdenum
    ( 2021-01-01) ;
    Zulkefli N.A.
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    Saravanan R.
    ;
    ; ;
    Zakaria S.
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    Cobalt-Chromium Molybdenum (CoCrMo) alloy is categorized under hard to cut material due to its unique combination characteristics such as high strength and low thermal conductivity. However, there was a problem during machining hard alloy material which is rapid tool wear. The tool wear will cause changes at tooltip geometry consequently has significant influence on the chip forming. There are some factors that influence tool wear which are cutting parameters, type of drill bit, and cutting fluids. In this study, a series of experiment were conducted to investigate the effect of cooling conditions on tool wear and chip formation during drilling this material. The cooling conditions used were dry, pure Karanja oil (MQL condition), and combination of Hexagonal boron nitride (hBN) nanoparticles with Karanja oil (MQL condition). The experiment was conducted under constant cutting speed of 20 m/min, and feed rate of 0.07 mm/rev through holes. Each hole was inspected when the tool wear reached 0.3 mm. The result showed that mixed of hBN with Karanja Oil (MQL condition) had lowest growth of flank wear and produced more holes compared to dry and pure Karanja oil condition. In addition, for chip formation, the size of lamellae produced was finest compared to other conditions.
      37  2
  • Publication
    Machinability of Nickel Titanium Shape Memory Alloys: A Review
    Shape memory alloys of Nickel Titanium (NiTi) reveal a reversible diffusionless transition between phases, resulting in unique properties and applications. It is widely used in varieties of products; especially in aerospace and medical fields. Yet, these alloys known as hard-to-machine materials owing to their properties of unconventional stress-strain behaviour, high work strain hardening and high ductility. That’s why their machinability is a major issue. The common drawbacks are serious burr formation, rapid tool wear, poor surface quality and high cutting force. This paper puts forward any possibilities to enhance the machining performance through paper reviews from previous researchers. A notable finding is that the machinability issues can be reduced or lessened by changing the cutting parameters and cutting conditions in order to improve the machinability of NiTi alloys.
      5  33
  • Publication
    Improvement on the Surface Quality in Machining of Aluminum Alloy Involving Boron Nitride Nanoparticles
    ( 2021-01-01) ;
    Zaibi N.M.
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    Harun A.
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    ;
    Zakaria S.
    Aluminum Alloys are used in a variety of applications due to their lightweight, strength-to-weight ratio and relatively ease of fabrication. In aerospace industry, millions of holes drilled annually on airframe structures. Normally, cutting fluids have been used to help reduce friction and heat. However, the use of cutting fluid is one of the major concerns when considering the environmental issues in machining. The disposal of used cutting fluid poses problems to the environment. This research investigates the effect of greener technique; hexagonal Boron Nitride nanoparticles dispersed in oil as compared to dry cutting and oil alone in through hole drilling operation Their impact on tool wear, surface roughness, and holes quality in terms of diameter accuracy, circularity and cylindricity were experimentally studied. Results showed that application of hexagonal Boron Nitride improved surface finish and produced better dimensional hole accuracy. The work clearly shows the important of nanoparticles in improving machinability of this material.
      2  32
  • Publication
    Crack Detection on Sheared-Edge of Ultra-High Strength Steel Sheet by Using Acid Immersion
    ( 2020-07-09)
    Azzmer S.
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    Jaafar H.
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    Tajul L.
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    Sulaiman M.H.
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    In trimming of ultra-high strength steel (UHSS) sheet, the high strength of the sheet usually results in large fracture and low burnish surfaces on the sheared-edge. For metal stamping industries, large fracture surfaces are unwanted, as it not only deteriorates sheared-edge quality but also leads to delayed-crack. In this study, crack detection by using acid immersion on the sheared-edge of ultra-high strength steel sheet caused by the trimming process was investigated. The ultra-high strength steel sheet of JSC780YN, JSC980YN, and JSC1180YN having different strengths were trimmed and immersed in 35% hydrochloric acid under a controlled time interval. The steel sheet with higher strength was found to produce larger fracture surface after trimming, i.e. more than 50% of the entire sheared-edge is fracture surface. Besides, the larger fracture surface of the steel sheet results in higher crack exposure and higher crack propagation, which in the long run, it can cause failure to the part manufactured using UHSS.
      1  19
  • Publication
    Machinability of nickel-titanium shape memory alloys under dry and chilled air cutting conditions
    ( 2023) ;
    Paul Tarisai Mativenga
    Nickel-titanium (NiTi) shape memory alloys (SMAs) undergo phase transformation between austenitic and martensitic phases in response to applied thermal or mechanical stress, resulting in unique properties and applications. However, machinability often becomes challenging due to property and temperature sensitivity attributes. The use of chilled air to influence machinability in macro-milling was investigated in this study. Other than that, differential scanning calorimetry (DSC) was used to determine the temperature of phase transformation. The results showed that milling with chilled air and minimal lubrication significantly improved machining performance by reducing tool wear and burr formation. Moreover, surface quality has also improved significantly. A notable discovery is that the machining process can change the critical conditions for phase transition, enabling new performance capability of tuning material hysteresis.