Papers by Keyword: Surface Finish

Abstract: The form, shape and dimensions of the scaled down winglet model become small and thin bringing complexity to manufacturing. The trailing edge tapers to a thickness varying from 0.065mm to 0.099mm along its length. The mounting portion of the winglet is provided with a close tolerance having a slot gap of 5mm and a depth of 35 mm with an angle. Additionally, wind tunnel models require good surface finish on the aerodynamic surfaces and this involves adopting a manufacturing strategy with a control over on the metal cutting parameters to be implemented on a three axes CNC machining centre. The winglet surface is divided into segments in order to handle the cutting forces on the varying aerodynamic cross section. Various metal cutting parameters such as tool path, cutter diameter, feed rate, depth of cut, spindle speed, etc., are evaluated by monitoring segments where the metal cutting is carried out [1] and flow of chips observed. Fixtures and lugs are planned effectively to accommodate the machining of the angular slot in a three axes machining centre itself. Routing of operations to handle the varying thin sections and realisation of the close tolerance slot has enabled a reliable manufacturing approach in an economical way.

Abstract: The Al-Si alloy is a structural material which generally consists of two or more particulates. However, Al-Si alloys are the most common alloys and commercially available ones due to their economical production. The utilization of Al-Si alloys has given the scope of study to improve in its properties using some grain refiner like Al-5Ti-1B, Al-3B and modifiers like Al-10Sr. The Al alloys were selected based on the economical uses and also, on the basis such that hypoeutectic (i.e., LM-25), eutectic (i.e., LM-6) and hypereutectic (i.e., LM-30). This project aimed to synthesize Al alloys (LM-6, LM-25 and LM-30) by melt stirring method with varying amount of grain refiners and / or modifier. The Prepared composites were characterized for machining properties. Alloys were evaluated for their machining properties which include surface roughness, lathe and drill tool dynamometer and comparing the machining properties with the minor addition of grain refienrs and/or modifier. The study concluded that, the addition of Al-3B to eutectic (i.e., LM-6) alloys has better surface finish.

Abstract: This paper is related to the air jet assisted machining method for a titanium alloy, Ti-6Al-4V ELI. The air jet assisted machining method is a new machining method, in which jet of the compressed air is applied to a tool tip together with flood coolant for reducing tool wear and also for extending tool life. In this experimental study, the new method was used in high-speed end milling for confirming the effect on tool life extension. Also, the optimal position of the jet nozzle was found. It was spotted that the new method is highly effective in reducing tool wear even at a high cutting speed. It is particularly noticeable that flank wear near the corner land, which is often severely damaged, was considerably reduced by the method. It turned out that the cutting forces and the degree of surface roughness observed through this method were almost the same as those through an ordinary method with flood coolant alone.

Abstract: This research develops a hybrid micromanufacturing technique by combining micromilling and electrochemical micropolishing to fabricate extremely smooth surface finish, high aspect ratio, and complex microchannel patterns. Milling with coated and uncoated ball-end micromills in minimum quantity lubrication is used to remove most materials to define a channel pattern. The milled channels are then electrochemically polished to required finish. A theoretical model accurately predicts surface finish in meso-scale milling, but not in micro-scale milling due to size effect. Electrochemical polishing using an acid-based electrolyte is applied to repeatedly produce stainless steel microchannels with average surface finish of 100 nm when measuring across grain boundaries and 10 nm within a single grain.

Abstract: Electrical discharge machining (EDM) is one of the most commonly used technique to machine very hard materials. Materials like hardened tool steels, titanium and its alloys and difficult-to-machine materials can be easily processed with EDM. The machining performance to a great extent depends on the composition of the electrode. This paper presents the machining performance of powder metallurgy (PM) compacted electrodes made from titanium carbide (TiC) and copper (Cu) powders. The Cu-TiC electrodes made up of 70% of TiC and 30% of Cu powders. They were compacted at a pressure of 6,000 psi (41.34 MPa). Mild steel was used as the workpiece material. Machining was conducted with the peak current, pulse-on time and pulse-off time as the electrical input variables. The output variables of the investigation were work surface roughness and its hardness. It was found that work surface roughness increases with increase in current and pulse-on-time. However, it decreases with increase in pulse-off time. It was found that the highest value of surface roughness (14.782 μm) was found at highest peak current (6.5 A), highest pulse on-time (7.5 μs) and lowest pulse-off time (6.5 μs). The highest value of surface hardness (57.3 BHB) was found at the same machining conditions. The smoothest surface (14.782 μm) was found at the lowest peak current (3.5 A), lowest pulse on-time (6.0 μs) and highest pulse-off time (8.5 μs). The lowest value of surface hardness (42.9 BHB) was found at the same machining conditions.

Abstract: In electronics industries, most of them had to shifted their solder materials from leaded solders into lead-free solders due to the environmental concerns and follow the legislation of Restriction of use Hazardous Substances (RoHS). Thus, Sn-Ag-Cu solder is one of the choices that can replace the leaded solder and also offer better properties. This study investigates the comparison between Sn-4.0Ag-0.5Cu (SAC405) and EN(P)EPIG and EN(B)EPIG surface finishes. Reliability of solder joint has been assessed by performing solid state isothermal aging at 150oC for 250 up to 2000 hours. After reflow soldering process, (Cu,Ni)₆Sn₅ intermetallic compound (IMC) is dominated at near centre of solder meanwhile (Ni,Cu)₃Sn₄ IMC is dominated at near outside of solder ball_. Moreover, aging time resulted in an increase in thickness and changed the morphology into more spherical, dense and large grain size. Analysis by optical microscope revealed that the IMC thickness of EN(B)EPIG produced thicker IMC compared to EN(P)EPIG surface finish during reflow as well as isothermal aging.

Abstract: Double angle drills have recently been used to improve the surface finish in drilling. The double angle drill consists of lower edges at a large wedge angle and upper edges at a small wedge angle on the lips. The paper discusses the cutting processes of the double angle drill in analysis and experiment. A force model is applied to simulate the cutting force and the chip flow direction. The cutting tests are conducted to verify the force model in drilling of carbon fiber reinforced plastic (CFRP) and aluminum alloy (A7075) with a single and a double angle drills. The double angle drill is effective in control of delamination in drilling of CFRP due to reduction of the thrust force. Meanwhile, in drilling of A7075, the small wedge angle of the upper edges on the double angle drill is not effective in reduction of the thrust forces. The curved edge at the end of the lip, in turn, promotes burr formation in drilling of A7075. The effectiveness of the double angle drill depends on the workpiece material.

Abstract: The machining of hard turning is performed on hardened steel in the range of 45 to 68 Rockwell hardness using a variety of tool materials such as Polycrystalline cubic boron nitride (PCBN) , Polycrystalline diamond (PCD) and Cubic boron nitride (CBN). It is an alternative to conventional grinding process is a flexible and effective machining process for hardened metals and hence broadly used in various applications such as dies, moulds, tools, gears, cams, shafts, axles, bearings and forgings. Although the process is performed within small depth of cut and feed rates, estimates to reduce machining time as high as 60 % in hard turning. This paper discusses the importance of hard turning of AISI D2 steel. In this study, Experimental investigations are carried out on conventional lathe using prefixed the cutting conditions. The responses studied in the investigation are cutting forces (F_a, F_t and F_z). The cutting parameters considered for the investigation are cutting speed, feed and depth of cut. The influence of machining parameters on response is studied and presented in detail.

Abstract: Innovative developments of hollow cellular mat for lightweight structure must satisfy sustainability, fit for purpose and optimize design concepts. However, such materials necessitate appropriate cutting technology to allow trimming and shaping operations to be easily carried out on an excessive porous and perhaps non uniformity nature. This paper presents a work that aims at studying the machinability of porous cellular mat using a newly innovative cutting technology. A large structure of vertical bandsaw has been fabricated to cut the product with the size of 1m (width) x 1m (height) x 1m (long). The systems also equipped with a feeding table and strong structure frame to avoid product shifting during the cutting operation. The surface integrity showed minimum deformation with uniformed direction of surface removal marks. The cutting technology developed in this study is suitable for the hollow cellular mat for its simple trimming and shaping process and fine surface profile.

Abstract: Conventional investment casting is one of the old manufacturing processes. It involves expensive tooling for making sacrificial wax patterns to make ceramic moulds. However, with the emergence of rapid prototyping technologies, now it is possible to make and use plastic patterns instead of wax patterns along with some advantages. In this paper, plastic patterns have been prepared by using fused deposition modeling and used for investment casting process. A case study has been discussed to make a biomedical implant by the hybridization of fused deposition modeling with investment casting. Dimensional accuracy, surface finish and hardness of the casted biomedical implants have been tested and reported.