Noor Hakim Rafai

An investigation of cutting mechanics in 2 dimensional ultrasonic vibration assisted milling toward chip thickness and chip formation

The purpose of this paper is to investigate the effects of 2 dimensional Ultrasonic Vibration Assisted Milling (UVAM) cutting mechanics, considering tool path trajectory and the effect on the chip thickness. The theoretical modelling of cutting mechanics is focused by considering the trajectory of the tool locus into the workpiece during the machining. The studies found the major advantages of VAM are come from the intermittent tool tip interaction phenomena between cutting tool and workpiece. The reduction of thinning chip thickness formations can be identifying advantages from vibration assisted milling in 2 dimensional. The finding will be discussing the comparison between conventional machining the potential of the advantages toward the chip thickness and chip formation in conclusion.

Numerical analysis of laser preheating for laser assisted micro milling of Inconel 718

Micro milling of super alloy materials such as nickel based alloys such as Inconel 718 is challenging due to the excellent of its mechanical properties. Therefore, new techniques have been suggested to enhance the machinability of nickel based alloys by pre-heating the workpiece’s surface to reduce its strength and ductility. The prediction of fluctuated temperature distribution generated by pulsed wave laser in laser assisted micro milling (LAMM) is crucial. The selection of processing parameter by minimize the effect on the processing characteristic is decisive to ensure the machining quality is high. Determining the effect of heat generated in underneath surface is important to make sure that the cutting tools are able to cut the material with maximum depth of cut and minimum defects in terms of tool wear and tool life. In this study the simulation was carried by using Ansys APDL. In order to confirm the actual and distribution irradiation of temperature from simulation, an experimental was done to validate the results. The experiment was conducted by using Nd:YAG laser with wavelength 1064 nm.

Dissimilar Materials Laser Welding Characteristics of Stainless Steel and Titanium Alloy

Welding parameters are directly influenced by the work material properties. Thermal properties such as thermal conductivity and melting point are very important to estimate the range of power required and the allowable scanning speed. However, when two or more different materials are involved, modifying lasing parameters are not enough to counter the problems such as imbalance melting region and weak adhesion of contact surface. To counter this problem, the characteristics of welding beads formation for both materials need to be clarified. In this study, comparison of welding beads constructed using the same scanning parameters were done to understand the different and similarity of melted region for the both materials. Actual welding of the both materials were done under different offset distance to obtain a balanced melting area and well mixed melting region.

Dimensional Accuracy Achievable in Wire-cut Electrical Discharge Machining

Wire-cut electrical discharge machining (WEDM) is a popular choice for machining hard and difficult to machine materials with very close tolerances. However, the widely held assumption of the high accuracy of WEDM needs to be investigated, which is the primary aim of this research. This work presents the experimental and analytical results of an investigation into the dimensional accuracy achievable in WEDM. Three techniques—traditional analysis, the Taguchi method, and Pareto ANOVA—are employed to determine the effects of six major controllable machining parameters: the discharge current, pulse duration, pulse gap frequency, wire speed, wire tension, and dielectric flow rate on three key dimensional accuracy characteristics of the prismatic component parts—linear dimensional errors, flatness errors, and perpendicularity errors of corner surfaces. Subsequently, the input parameters are optimized in order to maximize the dimensional accuracy characteristics. The results indicate that the dimensional accuracy that is achievable in WEDM is not as high as anticipated.

Comparison of Dry and Flood Turning in Terms of Dimensional Accuracy and Surface Finish of Turned Parts

This work presents experimental and analytical results of a comparison of dry and flood turning in terms of dimensional accuracy and surface finish of turned parts. Subsequently, the influence of independent input parameters on dimensional accuracy and surface finish characteristics is investigated in order to optimize their effects. Three techniques—traditional analysis, Pareto ANOVA, and the Taguchi method—are employed. Hardened alloy steel AISI 4340 has been selected as work material. The results show that for certain combinations of cutting parameters, dry turning produced better dimensional accuracy compared to that produced by flood turning. Therefore, in the future, it will be possible to develop a system through modelling the cooling process that will be capable of predicting the situations where dry turning will be beneficial. This will reduce the application frequency of cutting fluids by avoiding their unnecessary applications and, consequently, their negative impact on the environment.

The Effect of Machining Parameters on Surface Integrity when Milling Hardened Steel

This study discussed about the influence of the cutting speed and radial depth of cut on surface integrity (microhardness and work-hardening) when performing hard milling of AISI D2 workpiece. By using PVD-TiAlN, nine experimental trials were performed at various cutting speeds of 80, 100 and 120 m/min and various radial depth of cut of 3, 4 and 5 mm as feed and depth of cut remain constant at 0.05 mm/tooth and 0.05 mm. From the result, due to high cutting temperature generated, the cutting speed adversely affects the microhardness value of the subsurface layer. At higher cutting speed of 120 m/min higher hardness values were obtained when compared with lower cutting speed of 80 m/min. As for the effect of the radial depth of cut it is clear that it influences the microhardness beneath the surface. Higher microhardness recorded from the radial depth of cut increment associated with high cutting temperature generated during machining.

Optimisation of Processing Condition Using Taguchi Method on Warpage for HDPE-Clay Composite

Injection molding is one of the most important processes in manufacturing nowadays. Thus, attention must be give towards the optimization of the product defects. Parameters have been chosen by screening tests to improve the process quality. The main purpose of this study is to optimize the processing condition using Taguchi Method on shrinkage for HDPE-Clay specimen. The experiment starts by preparing the mixture between HDPE and clay. Then, screening test is conducted to obtain the parameters. The parameters are melt temperature, injection speed, injection pressure and cooling time. By using the array orthogonal L9 (34), signal to noise ratio and ANOVA were conducted. Based on the S / N ratio analysis, best combination can be produced for warpage (melt temperature: 190°C, injection speed: 40%, injection pressure: 30% and cooling time: 3 seconds). While for ANOVA, melt temperature is most significant with 60.28% for warpage.

Melted Zone Shapes Transformation in Titanium Alloy Welded Using Pulse Wave Laser

The study demonstrates laser welding of titanium alloy Ti6Al4V using middle range power Nd:YAG laser. Butt welding cross section views were analyzed to understand the influence of several scanning parameters to the welding beads shapes and material characteristic changes. Pulse laser was used to perform welding on titanium alloys Ti6Al4V. It was found out that fusion zone can appear in two layers which could give clues to internal temperature distribution during the scanning process.

Effect of Variable Pitch on Cutting Temperature, Cutting Forces and Surface Roughness Using Nitico30 Cutting Tool when End Milling of Stainless Steel 316L

In this paper, a series of milling tests were carried out in order to identify the effects of variable pitch on cutting temperature, cutting force and surface roughness while end milling the stainless steel 316L using Nitico30 and conventional cutting tools. Slot-milling operations were conducted. The value of feed rate were choose between the range recommended by the manufactured for the both conventional and Nitico30 cutting tool. The effect of variable pitch on cutting temperature, cutting forces and surface roughness were discussed. Results showed that the cutting temperature increase with the increase of feed rate for both cutting tool. Further increasing the speed of feed rate, the cutting forces also gradually increase for both cutting tool. However, the comparison between both cutting tools, it was found that the cutting temperature, cutting force and surface roughness improve about 47.8%, 37.5% and 17.6% respectively for Nitico30 cutting tool.

Laser Micro Welding of Dissimilar Material of Aluminum and Copper Alloys

Copper and aluminum are widely used in electronic industries for their excellence in electric and thermal conductivity. Joining these different material in scale of micro is hardly difficult for their obvious different in thermal properties. Melting these materials during welding process will create intermetallic compound which possesses new material properties. The melted zone became extremely brittle thus increase the possibility of failure due to cracks and concentrated loads. To overcome this problem, fundamental study is needed to characterize the material behavior against heat induction under various processing parameters. This study is an attempt to characterize the performance of Nd-YAG laser in micro joining of Al 1100 and Cu 101.