Mohammad Nazrul Islam

AN INVESTIGATION INTO DIMENSIONAL ACCURACY AND SURFACE FINISH ACHIEVABLE IN DRY TURNING

This paper presents experimental and analytical results of an investigation into dimensional accuracy and surface finish achievable in dry turning. The Taguchi method and Pareto ANOVA analysis are used to determine the effects of the major controllable machining parameters, viz. cutting speed, feed rate and depth of cut, on three key quality characteristics, viz. diameter error, surface roughness and circularity, and subsequently to find their optimum combination. The work and tool materials selected are alloy steel AISI 4340 and enriched cobalt-coated carbide, respectively. The results indicate that while the surface roughness can be optimized through proper selection of feed rate, optimization of diameter error and circularity is difficult due to complex interactions between the input parameters.

Sustainable manufacturing for Indonesian small- and medium-sized enterprises (SMEs): the case of remanufactured alternators

Achieving sustainability is a great challenge for most of the Indonesian manufacturing small- and medium-sized enterprises (SMEs). Remanufacturing has been considered to be a key strategy to attain sustainable manufacturing by maximising the use of old components and minimising landfill size and energy usage. However, SMEs, which are undoubtedly the engine of the Indonesian manufacturing industry, do not have adequate experience, skill, resource, technology and financial support in the remanufacturing area. This paper proposes a new concept for sustainable manufacturing assessment framework through remanufacturing strategies in Indonesian SMEs. In this sustainable manufacturing assessment framework, the existing remanufactured products are assessed using sustainable manufacturing criterion (e.g. reliability, life cycle cost, employment opportunity and greenhouse gases). This framework identifies improvement opportunities, including eco-efficiency, cleaner production and green technology to make existing remanufactured products technically, economically, environmentally and socially sustainable. The sustainability of remanufactured alternators produced by Indonesian SMEs has been assessed to validate the aforementioned sustainable manufacturing assessment framework.

Machining and tool wear mechanisms during machining titanium alloys

This paper investigates the machining mechanism of titanium alloys and analyses those understandings systematically to give a solid understanding with latest developments on machining of titanium alloys. The chip formation mechanism and wear of different cutting tools have been analyzed thoroughly based on the available literature. It is found that the deformation mechanism during machining of titanium alloys is complex and it takes place through several processes. Abrasion, attrition, diffusion–dissolution, thermal crack and plastic deformation are main tool wear mechanisms.

Electrical discharge machining of 6061 aluminium alloy

The wire electrical discharge machining (EDM) of 6061 aluminium alloy in terms of material removal rate, kerf/slit width, surface finish and wear of electrode wire for different pulse on time and wire tension was studied. Eight experiments were carried out in a wire EDM machine by varying pulse on time and wire tension. It is found that the material removal rate increases with the increase of pulse on time though the wire tension does not affect the material removal rate. It seems that the higher wire tension facilitates steady machining process, which generates low wear in wire electrode and better surface finish. The surface roughness does not change notably with the variation of pulse on time. The appearance of the machined surfaces is very similar under all the machining conditions. The machined surface contains solidified molten material, splash of materials and blisters. The increase of the pulse on time increases the wear of wire electrode due to the increase of heat input. The wear of wire electrode generates tapered slot which has higher kerf width at top side than that at bottom side. The higher electrode wear introduces higher taper.

EFFECT OF ADDITIONAL FACTORS ON DIMENSIONAL ACCURACY AND SURFACE FINISH OF TURNED PARTS

This article reports the experimental and analytical results of an investigation of additional factors that affect the dimensional accuracy and surface finish of turned parts besides the three major cutting parameters—cutting speed, feed rate, and depth of cut. The selected additional factors were cooling method, blank size, and work material. A three-level, three-parameter experiment was planned using design-of-experiment methodology. The three levels of independent input parameters were: for cooling method—dry turning, flood turning, and minimum quantity lubrication turning; for blank size—φ20, 40, and 60 mm; and for work material—aluminium 6061, mild steel 1030, and alloy steel 4340. The measured output parameters were the two most widely used dimensional accuracy characteristics of turned parts—diameter error and circularity—and the surface finish characteristic arithmetic average. The results were analyzed applying three methods: traditional analysis, Pareto ANOVA, and Taguchi method. The results reveal that, while work material has the greatest effect on diameter error and surface roughness, the major contributor to circularity is blank size.

Effect of reinforced particle size on wire EDM of MMCs

This paper investigates the effect of the size of reinforced particles on wire electrical discharge machining (EDM) of metal matrix composites (MMCs) in terms of material removal rate (MRR), surface integrity and wear of wire electrodes (WEs). It was found that larger particles significantly reduced the MRR, as they were better able to protect the matrix material from EDM sparks compared to smaller particles. The machined surfaces were full of solidified melted matrix, splashes of melted material, cavities and blisters, which are not significantly affected by particle size. Spattering and splashing might have contributed to the transfer of materials between the WE and the MMCs. The diameter of the WE was reduced nonlinearly with the increased size of the reinforced particles after machining. The smallest reduction in electrode diameter occurred in the unreinforced matrix material.

A comparison of repaired, remanufactured and new compressors used in Western Australian small- and medium-sized enterprises in terms of global warming

Repaired compressors are compared with remanufactured and new compressors in terms of economic and environmental benefits. A detailed life cycle assessment has been carried out for compressors under three manufacturing strategies: repaired, remanufactured and new equipment. The life cycle assessment of the global warming potential of repaired compressors varies from 4.38 to 119 kg carbon dioxide equivalent (CO2-e), depending on the type of components replaced. While greenhouse gas emissions from the remanufactured compressors (110 to 168 kg CO2-e) are relatively higher than those from the repaired ones (4.4 to 119 kg CO2-e), a new compressor has been found to produce a larger amount of greenhouse gas emissions (1,590 kg CO2-e) compared to both repaired and remanufactured compressors. Repairing failed compressors has been found to offer end users both dollar and carbon savings in contrast to remanufactured and new compressors. The research also found that extended lifetime is more important than the manufacturing processes in terms of greenhouse gas emissions. Since a remanufactured compressor offers a longer life than a repaired compressor, the replacement of the latter with the former can avoid 33% to 66% of the greenhouse gas emissions associated with a new compressor production with a lifetime of 15 to 25 years.

Failure Mechanisms of Nanoparticle Reinforced Metal Matrix Composite

The quest for the advanced functional material of superior functionality for advanced structure is being driven in various fronts of engineering materials. One of such front is metal matrix composite (MMC) which has already been proven as one of the most productive field in that respect. With the advance of technology, now it is possible to reinforce the MMCs with nanosized particles compared to conventional micron-sized ones. However, the addition of nanoparticle in the MMC to improve its mechanical properties is not unconditional. To achieve positive gain by adding nanoparticles in the MMCs, all the influencing factors should be taken into consideration. The present paper reviews the failure mechanisms of nanoparticles reinforced MMCs in light of its strengthening mechanisms.

A simple heuristic for linear sequencing of machines in layout design

This paper presents a simple heuristic to determine a common linear machine sequence for multiple products with different operation sequences and a limited number of duplicate machine types available for the job. The heuristic is based on minimisation of the total flow distance travelled by a product on the linear machine sequence. It is assumed that the flows of products are allowed only in the forward direction, either in-sequence or by-pass. It is also assumed that backtrack movements are not allowed. The effectiveness of the proposed heuristic is demonstrated through the solutions of two typical layout design problems taken from the literature. Subsequently, a number of additional problems are solved and their results are compared with the results applying existing methods. The results indicate that the proposed method can be an effective tool in solving layout design problems.

Effect of machining parameters on the surface finish of a metal matrix composite under dry cutting conditions

The machining of aerospace materials, such as metal matrix composites, introduces an additional challenge compared with traditional machining operations because of the presence of a reinforcement phase (e.g. ceramic particles or whiskers). This reinforcement phase decreases the thermal conductivity of the workpiece, thus, increasing the tool interface temperature and, consequently, reducing the tool life. Determining the optimum machining parameters is vital to maximising tool life and producing parts with the desired quality. By measuring the surface finish, the authors investigated the influence that the three major cutting parameters (cutting speed (50–150 m/min), feed rate (0.10–0.30 mm/rev) and depth of cut (1.0–2.0 mm)) have on tool life. End milling of a boron carbide particle-reinforced aluminium alloy was conducted under dry cutting conditions. The main result showed that contrary to the expectations for traditional machined alloys, the surface finish of the metal matrix composite examined in this work generally improved with increasing feed rate. The resulting surface roughness (arithmetic average) varied between 1.15 and 5.64 μm, with the minimum surface roughness achieved with the machining conditions of a cutting speed of 100 m/min, feed rate of 0.30 mm/rev and depth of cut of 1.0 mm. Another important result was the presence of surface microcracks in all specimens examined by electron microscopy irrespective of the machining condition or surface roughness.