Ahmad Razlan Yusoff | Universiti Malaysia Pahang (UMP) (original) (raw)

Papers by Ahmad Razlan Yusoff

Lubricants

Efficient and effective lubricants have great application prospects in the manufacturing industri... more Efficient and effective lubricants have great application prospects in the manufacturing industries. Minimum quantity lubrication (MQL) machining with low flow rate of nanolubricants is investigated for cooling and lubrication during the process. This paper investigates the characterization of graphene-mixed aluminium oxide (G-Al2O3) hybrid nanomixture spent lubricants for MQL machining purposes. The main advantage of this method is to reduce the disposal lubricants to develop high-performance cooling-lubrication by using nanolubricants of G-Al2O3 nanoparticles in different volume composition ratios at a constant 1.0% volume concentration in a base liquid mixture of 40% spent lubricants. Before conducting the measurements of the nanolubricants’ thermal conductivity and dynamic viscosity, the nanolubricants were homogenous and stable. The tribological performance of all ratios was evaluated by using a four-ball wear tribotester machine. The thermal conductivity peak value for the G-A...

IOP Conference Series: Materials Science and Engineering, 2019

Machining coolant is used in manufacturing industry for lubrication, rusting control and cooling ... more Machining coolant is used in manufacturing industry for lubrication, rusting control and cooling which are crucial in operations such as grinding and cutting process. However, the machining coolant lose efficiency in months due to the thermal degradation and contamination. To recycle the used of machining coolant while enhancing the performance, the mixture of nanofluids (N) based Al2O3 with better thermal properties to synthesize with the recycled machining coolant (RMC). This study suspended Al2O3 nanofluids in four base ratios of recycled machining coolant (i.e. 0:100, 20:80, 40:60 and 60:40) by ultrasonic homogenies. The three main parameters in cooling rate performance and rusting control are thermal conductivity, dynamic viscosity and pH indication, respectively. The thermal conductivity and dynamic viscosity are then measured at temperature range of 30 to 60°C. The highest enhancement of thermal conductivity was evaluated to be 37.9% higher than machining coolant base fluid a...

Journal of Mechanical Engineering and Sciences, 2021

This paper presents a complete and well tested virtual instrument (VI) for computer numerical con... more This paper presents a complete and well tested virtual instrument (VI) for computer numerical control (CNC) machine predictive maintenance. The national instrument (NI) hardware, LabVIEW software and accelerometer sensor are acquired for the vibration analysis integrated with virtual instrument were developed based on the vibration severity chart threshold in ISO 10816. Validation experiments of the predictive maintenance module were utilized on drilling and milling processes to test and verify the effectiveness of the module. Results obtained from current module can monitor and provide the machine conditions at different condition of good, satisfactory, unsatisfactory, and unacceptable for rotating machinery status according to the vibration severity chart as per ISO 10816.

IOP Conference Series: Materials Science and Engineering, 2018

Occupational noise hearing loss with high level exposure is common occupational hazards. In CNC s... more Occupational noise hearing loss with high level exposure is common occupational hazards. In CNC striping process, employee that exposed to high noise level for a long time as 8-hour contributes to hearing loss, create physical and psychological stress that reduce productivity. In this paper, CNC stripping process with high level noises are measured and reduced to the permissible noise exposure. First condition is all machines shutting down and second condition when all CNC machine under operations. For both conditions, noise exposures were measured to evaluate the noise problems and sources. After improvement made, the noise exposures were measured to evaluate the effectiveness of reduction. The initial average noise level at the first condition is 95.797 dB (A). After the pneumatic system with leakage was solved, the noise reduced to 55.517 dB (A). The average noise level at the second condition is 109.340 dB (A). After six machines were gathered at one area and cover that area with plastic curtain, the noise reduced to 95.209 dB (A). In conclusion, the noise level exposure in CNC striping machine is high and exceed the permissible noise exposure can be reduced to acceptable levels. The reduction of noise level in CNC striping processes enhanced productivity in the industry.

International Journal of Machine Tools and Manufacture, 2011

It is well known that regenerative chatter can result in excessive tool wear, poor surface finish... more It is well known that regenerative chatter can result in excessive tool wear, poor surface finish, and hence limited productivity during metal machining. Various mitigation methods can be applied to suppress chatter; however, the current paper focuses on applying optimal variable helix tool geometry. A semi discretrisation method is combined with Differential Evolution to optimise variable helix end milling tools so as to avoid chatter by modifying the variable helix and variable pitch tool geometry. The semi discretrisation method is first validated experimentally. The numerical optimisation procedure is then used to optimise tool geometry for a machining problem involving a flexible workpiece. The analysis predicted total mitigation of chatter using the optimised variable helix milling tool at a low radial immersion. However, in practice a five fold increase in chatter stability was obtained, compared to the traditional milling tool.

Mekatronika, Jan 31, 2019

A dual level searching approach for multi objective optimisation problems using particle swarm op... more A dual level searching approach for multi objective optimisation problems using particle swarm optimisation and modified adaptive bats sonar algorithm is presented. The concept of echolocation of a colony of bats to find prey in the modified adaptive bats sonar algorithm is integrated with the established particle swarm optimisation algorithm. The proposed algorithm incorporates advantages of both particle swarm optimisation and modified adaptive bats sonar algorithm approach to handle the complexity of multi objective optimisation problems. These include swarm flight attitude and swarm searching strategy. The performance of the algorithm is verified through several multi objective optimisation benchmark test functions and problem. The acquired results show that the proposed algorithm perform well to produce a reliable Pareto front. The proposed algorithm can thus be an effective method for solving of multi objective optimisation problems.

Journal of Mechanical Engineering and Sciences, 2021

In modal analysis, measurement of input force and vibration response are crucial to accurately me... more In modal analysis, measurement of input force and vibration response are crucial to accurately measure the transfer function of the structure. However, under operating condition, the force induced by operating machinery is impossible to be measured due to the sensor placement issue. In this case, the ambient response induced by the operating force should be suppressed to minimize the error in the Frequency Response Function (FRF) calculation. This paper presents the utilization of a modified spectral subtraction filter for ambient suppression. The introduction of effective ambient magnitude in gain function calculation has increased the efficiency of spectral subtraction filter. This parameter is calculated based on the phase information of the reconstructed artificial ambient response. The measurement using EMA was carried out on a motor-driven structure to verify the proposed technique. Two sets of data under shutdown and running condition were recorded to observe the effect of am...

Milling is one of the most common manufacturing processes for automotive components, but its prod... more Milling is one of the most common manufacturing processes for automotive components, but its productivity is limited by the onset of regenerative chatter. This is a form of unstable self-excited vibration that occurs when the volume of material removed is too large for a particular spindle speed. This form of chatter is undesirable because it results in premature tool wear, poor surface finish on the machined component and the possibility of serious damage to the machine itself. The chatter stability of a milling process can be determined using well-established theory, provided that the frequency response of the flexible structure can be determined. In practice this usually involves the excitation of a stationery (non-rotating) milling tool with a modal hammer, and measurement of the response of the tool with a co-located accelerometer. However, this measurement is not necessarily accurate due to amplitude dependency factor consideration. There is anecdotal evidence that structural ...

Procedia CIRP, 2021

Abstract Machining operation must be maintained for a long time in every period to achieve high p... more Abstract Machining operation must be maintained for a long time in every period to achieve high productivity and prevent sudden failure or breakdown. This study aims to monitor conditions of four CNC machines from different places simultaneously using Internet of things (IoT) for predictive maintenance. Vibration signals of four CNC machines are measured using an accelerometer to collect and send signals directly to the database in real time. Results showed that acceleration signal in both time and frequency domains can identify conditions of each machine in real time and simultaneously monitor the condition of four CNC machines at different places through IoT for predictive maintenance.

Journal of Mechanical Engineering and Sciences, 2020

Nanofluids possess many advantages over conventional working fluid especially in physical, therma... more Nanofluids possess many advantages over conventional working fluid especially in physical, thermal and rheology properties. Nowadays, nanofluids have been applied extensively in many engineering applications in enhancing the overall performance. Preparation and characterization of nanofluids are vital as the nanomaterials have significant effects on the dispersion and stability of nanofluids. On the other hand, there is a trend to employ more than a single nanoparticle for preparing nanofluid. The hybrid nanofluid receives wide attention due to its capability in improving the thermal-physical properties of single phase nanofluids. In this paper, the flow of formulating nanofluid from preparation method, characterization, wettability analysis and stability techniques are discussed comprehensively. Furthermore, the challenges for obtaining stable suspension and wettability behaviour of nanofluids are discussed as well. The main objective when preparing the nanofluids is to obtain a we...

IOP Conference Series: Materials Science and Engineering, 2019

A chip breaker plays an essential role for chip breaking as well as to enhance productivity and q... more A chip breaker plays an essential role for chip breaking as well as to enhance productivity and quality during the turning process. However, chip break as a tool is not able to break the chip and formulate continuous chip, that in turn, causes the tool to wear and the generate excessive heat. These affect the quality of the machined surface. Chip formation is influenced by cutting conditions and tool geometries such as spindle speed, feed rate, depth of cut and rake angle. In this study, experiments were carried out on carbon steel 1050 with chip breaker at a constant cutting speed of 275 m/mm with a depth of cut 0.9 mm. The effect of different feed rate and rake angle towards chip length formation were also investigated in the present investigation. The results obtained from the study indicates that segmented chips could be obtained at a feed rate of 0.4 mm/rev and a rake angle of -9°. Therefore, it could be concluded that the feed rate and rake angle can play a significant role in...

ASEAN Journal on Science and Technology for Development, 2017

The paper presents an approach to investigate and monitor the air pollution caused by the palm oi... more The paper presents an approach to investigate and monitor the air pollution caused by the palm oil mill. A concept of dealing with the problem from its causes is used where the sources of pollution from the stack gases were examined. The main causes were from the combustion of shell fibre and of the palm oil. However, in the boiler itself, several parameters like steam load and pressure, fuel capacity and temperature also contribute to the pollution. The study uses Neural Network (NN) to simulate the process of combustion and stack gases. This neural network was trained by using the data on emission and combustion bed taken from local palm oil plant in Perak, Malaysia. The trained data by NN agrees well with the measured data, i.e. almost within 8% error for pollutants like CO, SO2, NO and particulate matters.

Chatter produces a poor surface finish and high tool wear and can even damage machine tools as a ... more Chatter produces a poor surface finish and high tool wear and can even damage machine tools as a result of the regenerative effect, the loss of the contact effect and the mode coupling effect. The early and latest researches are to suppress chatter by either passive or active methods by applying absorber, damping, varied speed and alternatives. In this paper, it can be observed that the optimization focuses on spindle design, tool path, cutting process and variable pitch for chatter suppression. There are various algorithms which can be applied in optimization of machining problems; however, Differential Evolution (DE) is the appropriate candidate that can solve time consuming, local optimal and more robust as compared to Genetic Algorithm (GA), although it has widely applications, and Sequential Quadratic Programming (SQP) as a famous conventional algorithm can be employed for chatter suppression.

Journal of Physics: Conference Series, 2009

... present study, a semi discretisation method (SDM) has been combined with Differential Evoluti... more ... present study, a semi discretisation method (SDM) has been combined with Differential Evolution (DE) to optimise variable helix end milling tools. The target is to reduce chatter, and Sequential Quadratic Programming (SQP) is used to benchmark the optimisation performance. ...

The International Journal of Advanced Manufacturing Technology, 2016

Deep twist drilling technique with length per diameter ratio of more than 10 is widely used, espe... more Deep twist drilling technique with length per diameter ratio of more than 10 is widely used, especially in tool and die industries. This technique can improve the quality and production of drilling products by increasing feed rate and can shorten the machining time. The limitation in this process is premature tool breakage due to tool wear, chip clogging, and tool failures. In this study, deep drilling process was analyzed via cutting force and vibrations by using three-axis force dynamometer and accelerometer sensors to detect failure criteria. Deep twist drills were analyzed through cutting parameters, such as cutting speeds, feeds, and depth of cut. The effects on the tool condition during cutting operations were measured by three-axis data of vibrations and force sensors and then analyzed in time and frequency domain. Results indicated that both sensors are capable of monitoring tool conditions. However, data produced by vibration sensors are more appropriate to detect initial conditions before tool failure. Thus, monitoring tool conditions in three axes can lead to precise data and earlier detection in the y axis instead of in the z axis. Cutting condition analysis found that cutting speed and feeds of more than 50 m/min and 0.25 mm/rev, respectively, result in tool failures under safety threshold in x, y, and z. Tool monitoring conditions in three axes are useful to show the deep drilling process failure criterion, such as good, small corner wear, large corner wear, blunt, and fracture. Tri-axial sensors are useful in developing an online condition monitoring tool for deep drilling process, especially in tool and die industries.

High productivity, low cost and high profits are important issues in aerospace, automotive and to... more High productivity, low cost and high profits are important issues in aerospace, automotive and tool/die metal manufacturing industries. Machining processes are widely used in manufacturing operations for metal manufacturing rather than casting and forming. However, the dynamic deflection of tool and workpiece systems generates unstable cutting forces when machining with high material removal rate. Here, sudden large vibration amplitudes occur when energy input exceeds the energy dissipated from the system, leading to self-excited vibration or chatter. This thesis focuses on the avoidance of milling chatter by using variable helix milling tools. Since milling chatter is strongly influenced by the frequency response function of the dynamic system, a preliminary study is first presented to assess the feasibility of non-contacting electromagnetic modal analysis for milling tools. It is shown that this approach shows some promise for use in real machining problems where traditional modal...

IOP Conference Series: Materials Science and Engineering, 2016

Measurement, 2016

Machine tools are the main driving forces of industrialization of a country. However, poor machin... more Machine tools are the main driving forces of industrialization of a country. However, poor machinability because of chatter vibration results in poor surface quality, excessive noise, and reduced material removal rate. Modal testing is a useful method to investigate dynamic properties of a cutting tool system and improve material removal rate. However, at present, modal testing using impact hammer is limited by certain problems. This paper developed a non-contacting electromagnetic actuator (EMA) to determine frequency response functions (FRFs) under amplitude and speed dependencies of cutting milling tools. The geometry was designed using magnetic circuit analysis and generalized machined theory before finite element analysis was conducted using magnetostatic-ansys software. Next, EMA was used as a contacting and non-contacting exciter of a conventional milling machine to determine the FRFs and dynamic properties of milling tool with amplitude and speed dependencies including comparison with static FRFs. Subsequently, dynamic properties and FRFs are used to establish stability lobe diagram. Stability lobe diagram also shows an improvement of up to 5% of depth of cut at lower spindle speed. In conclusion, by generating force that applies to static and dynamic modal testing, an EMA can determine dynamic properties and stability lobe diagram for increasing material removal rate and production rate.

Advanced Materials Research, 2015

The elastic relaxation behavior of dual phase steel DP800 is studied in this investigation, based... more The elastic relaxation behavior of dual phase steel DP800 is studied in this investigation, based on experimental and numerical methods the true stress-true strain curve obtained from a standard uniaxial tensile test differs according to angular rolling direction The relationship between true stress and true strain are presented in the form of power law equation. This form of material constitutive model shows that the strength coefficient and strain hardening exponent vary significantly in describing the nonlinear true stress-true strain relationship of the material. Finite Element (FE) calculations with Belytschko-Lin-Tsay shell element formulation are performed using the non-linear FE code Ls-Dyna to predict the plastic deformation of the material. Power Law Isotropic Plasticity criterion is adopted for these numerical analyses. The local strains in plastic deformations zone and true stress-strains characteristics obtained by experiment are compared. Using the same parameter the s...

The Korean Society for the Study of Obesity (KSSO) has defined the waist circumference cutoff val... more The Korean Society for the Study of Obesity (KSSO) has defined the waist circumference cutoff value of central obesity as 90 cm for men and 85 cm for women. The purpose of this investigation was to determine the corresponding waist circumference values. A total of 3,508 persons in the Korean Rural Genomic Cohort Study were enrolled in this survey. Receiver operating characteristic (ROC) curve analysis was used to find appropriate waist circumference cutoff values in relation to insulin resistance determined by homeostasis model assessment for insulin resistance (HOMA-IR), body mass index (BMI), and components of metabolic syndrome. The optimal waist circumference cutoff values were 87 cm for men and 83 cm for women by ROC analysis to HOMA-IR and 86 cm for men and 83 cm for women by ROC analysis to value with more than two components of metaobolic syndrome. By using a BMI ≥25 kg/m 2 , 86 cm for men and 82 cm for women were optimal waist circumference cutoff values. In this study, we suggest that the most reasonable waist circumference cutoff values are 86-87 cm for men and 82-83 cm for women.

Lubricants

Efficient and effective lubricants have great application prospects in the manufacturing industri... more Efficient and effective lubricants have great application prospects in the manufacturing industries. Minimum quantity lubrication (MQL) machining with low flow rate of nanolubricants is investigated for cooling and lubrication during the process. This paper investigates the characterization of graphene-mixed aluminium oxide (G-Al2O3) hybrid nanomixture spent lubricants for MQL machining purposes. The main advantage of this method is to reduce the disposal lubricants to develop high-performance cooling-lubrication by using nanolubricants of G-Al2O3 nanoparticles in different volume composition ratios at a constant 1.0% volume concentration in a base liquid mixture of 40% spent lubricants. Before conducting the measurements of the nanolubricants’ thermal conductivity and dynamic viscosity, the nanolubricants were homogenous and stable. The tribological performance of all ratios was evaluated by using a four-ball wear tribotester machine. The thermal conductivity peak value for the G-A...

IOP Conference Series: Materials Science and Engineering, 2019

Machining coolant is used in manufacturing industry for lubrication, rusting control and cooling ... more Machining coolant is used in manufacturing industry for lubrication, rusting control and cooling which are crucial in operations such as grinding and cutting process. However, the machining coolant lose efficiency in months due to the thermal degradation and contamination. To recycle the used of machining coolant while enhancing the performance, the mixture of nanofluids (N) based Al2O3 with better thermal properties to synthesize with the recycled machining coolant (RMC). This study suspended Al2O3 nanofluids in four base ratios of recycled machining coolant (i.e. 0:100, 20:80, 40:60 and 60:40) by ultrasonic homogenies. The three main parameters in cooling rate performance and rusting control are thermal conductivity, dynamic viscosity and pH indication, respectively. The thermal conductivity and dynamic viscosity are then measured at temperature range of 30 to 60°C. The highest enhancement of thermal conductivity was evaluated to be 37.9% higher than machining coolant base fluid a...

Journal of Mechanical Engineering and Sciences, 2021

This paper presents a complete and well tested virtual instrument (VI) for computer numerical con... more This paper presents a complete and well tested virtual instrument (VI) for computer numerical control (CNC) machine predictive maintenance. The national instrument (NI) hardware, LabVIEW software and accelerometer sensor are acquired for the vibration analysis integrated with virtual instrument were developed based on the vibration severity chart threshold in ISO 10816. Validation experiments of the predictive maintenance module were utilized on drilling and milling processes to test and verify the effectiveness of the module. Results obtained from current module can monitor and provide the machine conditions at different condition of good, satisfactory, unsatisfactory, and unacceptable for rotating machinery status according to the vibration severity chart as per ISO 10816.

IOP Conference Series: Materials Science and Engineering, 2018

Occupational noise hearing loss with high level exposure is common occupational hazards. In CNC s... more Occupational noise hearing loss with high level exposure is common occupational hazards. In CNC striping process, employee that exposed to high noise level for a long time as 8-hour contributes to hearing loss, create physical and psychological stress that reduce productivity. In this paper, CNC stripping process with high level noises are measured and reduced to the permissible noise exposure. First condition is all machines shutting down and second condition when all CNC machine under operations. For both conditions, noise exposures were measured to evaluate the noise problems and sources. After improvement made, the noise exposures were measured to evaluate the effectiveness of reduction. The initial average noise level at the first condition is 95.797 dB (A). After the pneumatic system with leakage was solved, the noise reduced to 55.517 dB (A). The average noise level at the second condition is 109.340 dB (A). After six machines were gathered at one area and cover that area with plastic curtain, the noise reduced to 95.209 dB (A). In conclusion, the noise level exposure in CNC striping machine is high and exceed the permissible noise exposure can be reduced to acceptable levels. The reduction of noise level in CNC striping processes enhanced productivity in the industry.

International Journal of Machine Tools and Manufacture, 2011

It is well known that regenerative chatter can result in excessive tool wear, poor surface finish... more It is well known that regenerative chatter can result in excessive tool wear, poor surface finish, and hence limited productivity during metal machining. Various mitigation methods can be applied to suppress chatter; however, the current paper focuses on applying optimal variable helix tool geometry. A semi discretrisation method is combined with Differential Evolution to optimise variable helix end milling tools so as to avoid chatter by modifying the variable helix and variable pitch tool geometry. The semi discretrisation method is first validated experimentally. The numerical optimisation procedure is then used to optimise tool geometry for a machining problem involving a flexible workpiece. The analysis predicted total mitigation of chatter using the optimised variable helix milling tool at a low radial immersion. However, in practice a five fold increase in chatter stability was obtained, compared to the traditional milling tool.

Mekatronika, Jan 31, 2019

A dual level searching approach for multi objective optimisation problems using particle swarm op... more A dual level searching approach for multi objective optimisation problems using particle swarm optimisation and modified adaptive bats sonar algorithm is presented. The concept of echolocation of a colony of bats to find prey in the modified adaptive bats sonar algorithm is integrated with the established particle swarm optimisation algorithm. The proposed algorithm incorporates advantages of both particle swarm optimisation and modified adaptive bats sonar algorithm approach to handle the complexity of multi objective optimisation problems. These include swarm flight attitude and swarm searching strategy. The performance of the algorithm is verified through several multi objective optimisation benchmark test functions and problem. The acquired results show that the proposed algorithm perform well to produce a reliable Pareto front. The proposed algorithm can thus be an effective method for solving of multi objective optimisation problems.

Journal of Mechanical Engineering and Sciences, 2021

In modal analysis, measurement of input force and vibration response are crucial to accurately me... more In modal analysis, measurement of input force and vibration response are crucial to accurately measure the transfer function of the structure. However, under operating condition, the force induced by operating machinery is impossible to be measured due to the sensor placement issue. In this case, the ambient response induced by the operating force should be suppressed to minimize the error in the Frequency Response Function (FRF) calculation. This paper presents the utilization of a modified spectral subtraction filter for ambient suppression. The introduction of effective ambient magnitude in gain function calculation has increased the efficiency of spectral subtraction filter. This parameter is calculated based on the phase information of the reconstructed artificial ambient response. The measurement using EMA was carried out on a motor-driven structure to verify the proposed technique. Two sets of data under shutdown and running condition were recorded to observe the effect of am...

Milling is one of the most common manufacturing processes for automotive components, but its prod... more Milling is one of the most common manufacturing processes for automotive components, but its productivity is limited by the onset of regenerative chatter. This is a form of unstable self-excited vibration that occurs when the volume of material removed is too large for a particular spindle speed. This form of chatter is undesirable because it results in premature tool wear, poor surface finish on the machined component and the possibility of serious damage to the machine itself. The chatter stability of a milling process can be determined using well-established theory, provided that the frequency response of the flexible structure can be determined. In practice this usually involves the excitation of a stationery (non-rotating) milling tool with a modal hammer, and measurement of the response of the tool with a co-located accelerometer. However, this measurement is not necessarily accurate due to amplitude dependency factor consideration. There is anecdotal evidence that structural ...

Procedia CIRP, 2021

Abstract Machining operation must be maintained for a long time in every period to achieve high p... more Abstract Machining operation must be maintained for a long time in every period to achieve high productivity and prevent sudden failure or breakdown. This study aims to monitor conditions of four CNC machines from different places simultaneously using Internet of things (IoT) for predictive maintenance. Vibration signals of four CNC machines are measured using an accelerometer to collect and send signals directly to the database in real time. Results showed that acceleration signal in both time and frequency domains can identify conditions of each machine in real time and simultaneously monitor the condition of four CNC machines at different places through IoT for predictive maintenance.

Journal of Mechanical Engineering and Sciences, 2020

Nanofluids possess many advantages over conventional working fluid especially in physical, therma... more Nanofluids possess many advantages over conventional working fluid especially in physical, thermal and rheology properties. Nowadays, nanofluids have been applied extensively in many engineering applications in enhancing the overall performance. Preparation and characterization of nanofluids are vital as the nanomaterials have significant effects on the dispersion and stability of nanofluids. On the other hand, there is a trend to employ more than a single nanoparticle for preparing nanofluid. The hybrid nanofluid receives wide attention due to its capability in improving the thermal-physical properties of single phase nanofluids. In this paper, the flow of formulating nanofluid from preparation method, characterization, wettability analysis and stability techniques are discussed comprehensively. Furthermore, the challenges for obtaining stable suspension and wettability behaviour of nanofluids are discussed as well. The main objective when preparing the nanofluids is to obtain a we...

IOP Conference Series: Materials Science and Engineering, 2019

A chip breaker plays an essential role for chip breaking as well as to enhance productivity and q... more A chip breaker plays an essential role for chip breaking as well as to enhance productivity and quality during the turning process. However, chip break as a tool is not able to break the chip and formulate continuous chip, that in turn, causes the tool to wear and the generate excessive heat. These affect the quality of the machined surface. Chip formation is influenced by cutting conditions and tool geometries such as spindle speed, feed rate, depth of cut and rake angle. In this study, experiments were carried out on carbon steel 1050 with chip breaker at a constant cutting speed of 275 m/mm with a depth of cut 0.9 mm. The effect of different feed rate and rake angle towards chip length formation were also investigated in the present investigation. The results obtained from the study indicates that segmented chips could be obtained at a feed rate of 0.4 mm/rev and a rake angle of -9°. Therefore, it could be concluded that the feed rate and rake angle can play a significant role in...

ASEAN Journal on Science and Technology for Development, 2017

The paper presents an approach to investigate and monitor the air pollution caused by the palm oi... more The paper presents an approach to investigate and monitor the air pollution caused by the palm oil mill. A concept of dealing with the problem from its causes is used where the sources of pollution from the stack gases were examined. The main causes were from the combustion of shell fibre and of the palm oil. However, in the boiler itself, several parameters like steam load and pressure, fuel capacity and temperature also contribute to the pollution. The study uses Neural Network (NN) to simulate the process of combustion and stack gases. This neural network was trained by using the data on emission and combustion bed taken from local palm oil plant in Perak, Malaysia. The trained data by NN agrees well with the measured data, i.e. almost within 8% error for pollutants like CO, SO2, NO and particulate matters.

Chatter produces a poor surface finish and high tool wear and can even damage machine tools as a ... more Chatter produces a poor surface finish and high tool wear and can even damage machine tools as a result of the regenerative effect, the loss of the contact effect and the mode coupling effect. The early and latest researches are to suppress chatter by either passive or active methods by applying absorber, damping, varied speed and alternatives. In this paper, it can be observed that the optimization focuses on spindle design, tool path, cutting process and variable pitch for chatter suppression. There are various algorithms which can be applied in optimization of machining problems; however, Differential Evolution (DE) is the appropriate candidate that can solve time consuming, local optimal and more robust as compared to Genetic Algorithm (GA), although it has widely applications, and Sequential Quadratic Programming (SQP) as a famous conventional algorithm can be employed for chatter suppression.

Journal of Physics: Conference Series, 2009

... present study, a semi discretisation method (SDM) has been combined with Differential Evoluti... more ... present study, a semi discretisation method (SDM) has been combined with Differential Evolution (DE) to optimise variable helix end milling tools. The target is to reduce chatter, and Sequential Quadratic Programming (SQP) is used to benchmark the optimisation performance. ...

The International Journal of Advanced Manufacturing Technology, 2016

Deep twist drilling technique with length per diameter ratio of more than 10 is widely used, espe... more Deep twist drilling technique with length per diameter ratio of more than 10 is widely used, especially in tool and die industries. This technique can improve the quality and production of drilling products by increasing feed rate and can shorten the machining time. The limitation in this process is premature tool breakage due to tool wear, chip clogging, and tool failures. In this study, deep drilling process was analyzed via cutting force and vibrations by using three-axis force dynamometer and accelerometer sensors to detect failure criteria. Deep twist drills were analyzed through cutting parameters, such as cutting speeds, feeds, and depth of cut. The effects on the tool condition during cutting operations were measured by three-axis data of vibrations and force sensors and then analyzed in time and frequency domain. Results indicated that both sensors are capable of monitoring tool conditions. However, data produced by vibration sensors are more appropriate to detect initial conditions before tool failure. Thus, monitoring tool conditions in three axes can lead to precise data and earlier detection in the y axis instead of in the z axis. Cutting condition analysis found that cutting speed and feeds of more than 50 m/min and 0.25 mm/rev, respectively, result in tool failures under safety threshold in x, y, and z. Tool monitoring conditions in three axes are useful to show the deep drilling process failure criterion, such as good, small corner wear, large corner wear, blunt, and fracture. Tri-axial sensors are useful in developing an online condition monitoring tool for deep drilling process, especially in tool and die industries.

High productivity, low cost and high profits are important issues in aerospace, automotive and to... more High productivity, low cost and high profits are important issues in aerospace, automotive and tool/die metal manufacturing industries. Machining processes are widely used in manufacturing operations for metal manufacturing rather than casting and forming. However, the dynamic deflection of tool and workpiece systems generates unstable cutting forces when machining with high material removal rate. Here, sudden large vibration amplitudes occur when energy input exceeds the energy dissipated from the system, leading to self-excited vibration or chatter. This thesis focuses on the avoidance of milling chatter by using variable helix milling tools. Since milling chatter is strongly influenced by the frequency response function of the dynamic system, a preliminary study is first presented to assess the feasibility of non-contacting electromagnetic modal analysis for milling tools. It is shown that this approach shows some promise for use in real machining problems where traditional modal...

IOP Conference Series: Materials Science and Engineering, 2016

Measurement, 2016

Machine tools are the main driving forces of industrialization of a country. However, poor machin... more Machine tools are the main driving forces of industrialization of a country. However, poor machinability because of chatter vibration results in poor surface quality, excessive noise, and reduced material removal rate. Modal testing is a useful method to investigate dynamic properties of a cutting tool system and improve material removal rate. However, at present, modal testing using impact hammer is limited by certain problems. This paper developed a non-contacting electromagnetic actuator (EMA) to determine frequency response functions (FRFs) under amplitude and speed dependencies of cutting milling tools. The geometry was designed using magnetic circuit analysis and generalized machined theory before finite element analysis was conducted using magnetostatic-ansys software. Next, EMA was used as a contacting and non-contacting exciter of a conventional milling machine to determine the FRFs and dynamic properties of milling tool with amplitude and speed dependencies including comparison with static FRFs. Subsequently, dynamic properties and FRFs are used to establish stability lobe diagram. Stability lobe diagram also shows an improvement of up to 5% of depth of cut at lower spindle speed. In conclusion, by generating force that applies to static and dynamic modal testing, an EMA can determine dynamic properties and stability lobe diagram for increasing material removal rate and production rate.

Advanced Materials Research, 2015

The elastic relaxation behavior of dual phase steel DP800 is studied in this investigation, based... more The elastic relaxation behavior of dual phase steel DP800 is studied in this investigation, based on experimental and numerical methods the true stress-true strain curve obtained from a standard uniaxial tensile test differs according to angular rolling direction The relationship between true stress and true strain are presented in the form of power law equation. This form of material constitutive model shows that the strength coefficient and strain hardening exponent vary significantly in describing the nonlinear true stress-true strain relationship of the material. Finite Element (FE) calculations with Belytschko-Lin-Tsay shell element formulation are performed using the non-linear FE code Ls-Dyna to predict the plastic deformation of the material. Power Law Isotropic Plasticity criterion is adopted for these numerical analyses. The local strains in plastic deformations zone and true stress-strains characteristics obtained by experiment are compared. Using the same parameter the s...

The Korean Society for the Study of Obesity (KSSO) has defined the waist circumference cutoff val... more The Korean Society for the Study of Obesity (KSSO) has defined the waist circumference cutoff value of central obesity as 90 cm for men and 85 cm for women. The purpose of this investigation was to determine the corresponding waist circumference values. A total of 3,508 persons in the Korean Rural Genomic Cohort Study were enrolled in this survey. Receiver operating characteristic (ROC) curve analysis was used to find appropriate waist circumference cutoff values in relation to insulin resistance determined by homeostasis model assessment for insulin resistance (HOMA-IR), body mass index (BMI), and components of metabolic syndrome. The optimal waist circumference cutoff values were 87 cm for men and 83 cm for women by ROC analysis to HOMA-IR and 86 cm for men and 83 cm for women by ROC analysis to value with more than two components of metaobolic syndrome. By using a BMI ≥25 kg/m 2 , 86 cm for men and 82 cm for women were optimal waist circumference cutoff values. In this study, we suggest that the most reasonable waist circumference cutoff values are 86-87 cm for men and 82-83 cm for women.