Surface defects in groove milling of Hastelloy-C276 under fluid coolant

This study aims to investigate surface integrity in groove milling of Hastelloy-C276 using coated carbide end mills under the application of water-based fluid coolant using different cutting parameters. Surface integrity was assessed by measuring surface roughness, using focus variation microscope, and investigating surface defects, using scanning electron microscope. Micro-chips re-deposition and long grooves dominated the machined surface at low cutting speed (24–50 m/min). While cracked and fractured re-deposited materials, grooves, large debris, and plastic flow dominated the machined surface at high cutting speed (70–120 m/min), consequently surface roughness increased with cutting speed. Nucleated cavities appeared at all cutting speeds but with different densities. Shallow depth of cut at low cutting speed gave negative effect on surface roughness due to the effect of the hardened layer. Overall, the best surface finish, with average roughness below 50 nm and minimum surface abuse, was obtained in the speed range of 24–50 m/min at feed rate of 1 µm/tooth and depth of cut deeper than 0.1 mm

Mechanical properties of WC-based hardmetals bonded with iron alloys: a review

Growing concerns over the use of cobalt as binder for WC-based hardmetals has directed research efforts towards finding a suitable alternative binder offering comparable or even superior properties than those found in WC–Co hardmetals. Complete substitution of cobalt by iron alloys has been extensively explored in several studies with significant improvements in mechanical properties of WC bonded with Fe alloys when carbon content addition is strictly controlled in powder composition. Asides from the commonly studied hardness and fracture toughness properties, transverse rupture strength property of this composites has also been observed to hold future promise with further development in the microstructural parameters such as porosity during sintering. This article reviews the progress in the mechanical properties of WC–Fe alloys hardmetals

Temperature distribution of micro milling process due to uncut chip thickness

A simplified model for micro milling process is presented, as well as results on temperature on tool and work piece. The purpose is to investigate on finite element modelling of two flute micro end milling process of titanium alloy, Ti6Al4V with prediction of temperature distribution. ABAQUS/Explicit has been chosen as solver for the analysis. A thermo-mechanical analysis was performed. First model was created by selecting medium carbon steel, AISI1045, as workpiece material for model validation purpose. Second model was created by modifying the workpiece material from AISI1045 to Ti6Al4V. The model consists of two parts which are tungsten carbide micro tool and workpiece. Johnson-Cook law model has been applied as material constitutive properties for both materials due to its severe plastic deformation occur during machining. Prediction on forces was obtained during the analysis. Model validation was done by comparing results published by Woon et al. in 2008. The results showed a good agreement in cutting force. Once this was proved, the same model was then modified to simulate finite element analysis in micro milling of Ti6Al4V. Prediction of temperature distribution of micro end mill of Ti6Al4V was done in relation of different undeformed chip thickness. The findings showed that temperature increases as undeformed chip thickness increases. Temperature distribution of Ti6Al4V and AISI1045 under same machining conditions was compared. Results showed that the highest temperature was concentrated at tool edge for Ti6Al4V

Experimental investigation on friction drilling of titanium alloy

Friction drilling is a green hole-making process that zealously utilizes the heat generated from the friction between the rotating conical tool and workpiece to create a bushing without generating chip. The difficult-to-machine materials with unique metallurgical properties have been developed to meet the demands of extreme applications. However, the major challenges of friction drilling on difficult-to-machine materials are the hole diameter accuracy, petal formation and tool wear. In this study, the effects of process parameters such as spindle speed and feed rate on bushing height and shape, hardness and tool wear in friction drilling of titanium alloy Ti-6Al-4V were experimentally investigated using tungsten carbide tool. Optical photographs have also been analyzed for better understanding of the chipless friction drilling process for different parametric settings. Experimental results indicated that the spindle speed has great influences for achieving better bushing formation and prolong the tool life. It was confirmed that the low spindle speed and low feed rate have great influences for achieving better bushing shape and height, prolong tool life and lower hardness that located adjacent to the hole wall. It also was discovered that the low thermal conductivity of Ti-6Al-4V caused to improper increment of frictional heat and surface temperature. This disadvantage leads to unsatisfactory bushing formation. This work demonstrated the performances of chipless friction drilling used on difficult-to-machine material that can offer a great prospective for a new product design and manufacturing

A study on properties of polymer-based additive manufacturing

In recent years, increasing interest in 3D Printing (3DP) has meant that printer usage is not limited to industrial purposes only, but is also for domestic usage by hobbyists for their individual needs. Polymer-based part production can now even be conducted outside the traditional factory environment. However, low grade printers pose some drawbacks, such as lower heat for material fusion, uncontrolled open ambience and limited nozzle size. These reduce the mechanical and aesthetical qualities as compared to parts fabricated using industrial grade printers. The study aims to perform some quality comparisons between 3D printed polymeric parts fabricated by both industrial and low cost printers, and subsequently to prove the hypothesis that the industrial grade printed part has a more reliable surface quality and mechanical properties. Specimens were fabricated using each printer type (Fused Deposition Modelling (FDM) represents the low cost printer and the Multi Jet Printer (MJP) is used for the industrial grade) and later tested for hardness and surface roughness. Comparisons were then made between different fabricating methods and also based on a literature study according to the type of materials. The experiments showed that both the surface roughness and hardness for the plastic parts fabricated by the industrial grade printer were better than those made by the domestic printer, and showed a good agreement with the results in the literature study. Therefore, for highly durable parts, it is suggested that industrial grade printers are used. One point to conclude the study, Rapid Prototyping is possible by any machine, but for Rapid Manufacturing that requires higher durability, it is better to use an industrial grade printer

Optimization of the Parameters for Surface Quality of the Open-source 3D Printing / Nor Aiman Sukindar...[et al.]

Fused deposition modeling (FDM) or three-dimensional (3D) printing are becoming ubiquitous today because it allows the fabrication of 3D products directly from computer-aided design software. The quality of 3D parts is influenced by several parameters that need to be carefully tuned to obtain a high-quality final product. The surface finish of the finished parts is one of the major factors to consider because it affects both the dimensional accuracy and the functionality of the piece. Thus, the present study focuses on improving the surface finish of parts produced by FDM by manipulating different parameters such as layer height, raster angle, extruder temperature, printing speed, and percent infill. Polylactic acid was used for this study, which is a material present in filament form, and was extruded using a newly developed 3D printer; the Taguchi’s 35 design-of-experiment method was used to design the experiment. The results indicate that raster angle, extruder temperature, and layer thickness are the most influential process parameters of the surface quality of the final product

Review of green building index in Malaysia; existing work and challenges

Energy is becoming one of the most critical and important aspect to the nation, countries with high percentage of energy and resources is considered powerful as nowadays energy and resources of the country is key measurement for its power and development. Economic improvement has now taken an imperative part in the current world as characteristic assets are a rare thing and accessible lodging area is decreasing with the blast of human population. Which increase the need of implementation of Green building construction to ensure sustainable development and reduce the consumption of resources. Green building is the act of building structures and utilizing procedures that are ecologically benevolent and asset productive all through a building's life-cycle from arrangement to outline, development, operation, upkeep, remodel and deconstruction. In Malaysia some world class Green Buildings have built in recent years, yet the idea of green buildings for general masses is in outset stage. During this paper, it will explore the overall of sustainable development with its concept and its importance of this approach and goals of green building. Advantages and elements of the assessment for Green building Index had been discussed with a number of the barriers to application and a review of existing mobile applications. In Malaysia, the dynamic development of practice development by the legislature, non-governmental associations and instruction, foundations in the recent years have demonstrated some empowering advance in this field as it had revealed in this paper

Detection, Localisation and Assessment of Defects in Pipes Using Guided Wave Techniques: A Review

This paper aims to provide an overview of the experimental and simulation works focused on the detection, localisation and assessment of various defects in pipes by applying fast-screening guided ultrasonic wave techniques that have been used in the oil and gas industries over the past 20 years. Major emphasis is placed on limitations, capabilities, defect detection in coated buried pipes under pressure and corrosion monitoring using different commercial guided wave (GW) systems, approaches to simulation techniques such as the finite element method (FEM), wave mode selection, excitation and collection, GW attenuation, signal processing and different types of GW transducers. The effects of defect parameters on reflection coefficients are also discussed in terms of different simulation studies and experimental verifications

Experimental Investigation on Friction Drilling of Stainless Steel AISI 304

Friction drilling is an unexplored manufacturing process to produce holes in thin-walled sheet metals. In this study, the effects of process parameters in friction drilling of austenite stainless steel investigated experimentally and statistically. It was confirmed, sufficient heat generation, which cause to better bushing shape and height, acceptable drilled-hole diameter and lowest roundness error result from low spindle speed and high feed rate. It was obtained, although effect of feed rate on hole-wall thickness was negligible; spindle speed has significant effect on that which is inverse from spindle speed effect on bushing height. Moreover, micro-hardness reduced gradually away from the drilled-hole edge. Observing on tool shape and wear damage using optical microscope and scanning electron microscope quantifies effects of spindle speed and feed rate on tool performance and tool wear characteristics. Results indicate that better performance of drilling tool obtained from lower spindle speed and high feed rate

The effect of process parameters in extruding scaffold design using synthetic biomaterials

Open-source 3D printers have become a popular technology for inexpensively and rapidly fabricating threedimensional products, including those for medical use. We developed and tested a nozzle for extruding synthetic biomaterials for fabricating scaffold structures that can be used as a medium for cell growth in, for instance, orthopedic replacements. The nozzle was designed iteratively to optimise the die angle, nozzle diameter, and liquefier shape for extruding bioresorbable polymers, and a thermal insulator was installed to maintain consistent temperature in the liquefier chamber. We then fabricated a range of scaffold structure parts with varying percentages of infill material and infill patterns. Analysis of variance tests show that the percentage of infill is a dominant factor affecting the porosity as well as the mechanical properties of the samples. Samples with 10%–30% of infill with a combination of lined infill patterns exhibited 50%–70% porosity with 12–20 MPa compressive strengths. These specifications are well-suited for cell growth. To demonstrate the feasibility of fabricating structures with consistent porosity with open-source printers, a humerus bone was 3D printed using both Polylactic acid (PLA) and polymethylmethacrylate (PMMA) filament, and the porosity was controllable. This study suggests that opensource 3D printers may be used for printing bone replacements in the near future