Saiful Anwar Che Ghani

A review of hydroxyapatite-based coating techniques: Sol-gel and electrochemical depositions on biocompatible metals.

New promising techniques for depositing biocompatible hydroxyapatite-based coatings on biocompatible metal substrates for biomedical applications have continuously been exploited for more than two decades. Currently, various experimental deposition processes have been employed. In this review, the two most frequently used deposition processes will be discussed: a sol-gel dip coating and an electrochemical deposition. This study deliberates the surface morphologies and chemical composition, mechanical performance and biological responses of sol-gel dip coating as well as the electrochemical deposition for two different sample conditions, with and without coating. The review shows that sol-gel dip coatings and electrochemical deposition were able to obtain the uniform and homogeneous coating thickness and high adherent biocompatible coatings even in complex shapes. It has been accepted that both coating techniques improve bone strength and initial osseointegration rate. The main advantages and limitations of those techniques of hydroxyapatite-based coatings are presented. Furthermore, the most significant challenges and critical issues are also highlighted.

Design and analysis of an internally cooled smart cutting tool for dry cutting

Cutting fluid is traditionally used to remove heat generated during the cutting process, but it can cause environmental pollution, health hazards, and high cost of production. Dry cutting, without using the cooling liquid, is thus desirable and promising for the machining industry to produce components and products, both ecologically and more economically. In this paper, an internally cooled cutting tool for dry cutting is presented as a temperature-sensored smart cutting tool in its own right, with further applications for adaptive machining purposes. The cutting tool is characterized by a simple changeable internal cooling structure near the cutting tip. Simulations were performed to study the theoretical cooling efficiency and to optimize the cooling structure by combining it with the Taguchi Method. Furthermore, cutting trials were carried out to validate the novel cutting tool experimentally.

A review of biocompatible metal injection moulding process parameters for biomedical applications

Biocompatible metals have been revolutionizing the biomedical field, predominantly in human implant applications, where these metals widely used as a substitute to or as function restoration of degenerated tissues or organs. Powder metallurgy techniques, in specific the metal injection moulding (MIM) process, have been employed for the fabrication of controlled porous structures used for dental and orthopaedic surgical implants. The porous metal implant allows bony tissue ingrowth on the implant surface, thereby enhancing fixation and recovery. This paper elaborates a systematic classification of various biocompatible metals from the aspect of MIM process as used in medical industries. In this study, three biocompatible metals are reviewed-stainless steels, cobalt alloys, and titanium alloys. The applications of MIM technology in biomedicine focusing primarily on the MIM process setting parameters discussed thoroughly. This paper should be of value to investigators who are interested in state of the art of metal powder metallurgy, particularly the MIM technology for biocompatible metal implant design and development.

Optimizing Heat Transfer Rate in an Internally Cooled Cutting Tool: FE- Based Design Analysis and Experimental Study

The machining process produces high local temperatures in the tool-chip and tool-workpiece contact areas, normally lead to negative influence on the machine performance. This paper presents a study on optimizing the internal micro channel structure of a tungsten carbide (WC) cutting tool in order to enhance heat transfer rate when applied with internal cooling fluid. Inspired by water jet impingement theory, the efficiency and heat transfer rate of single phase micro channel mainly depends on the fluid velocity as well as temperature difference between the cooling fluid and hot surface. In this study three variables, i.e. the space between channel and internal wall of the insert, channel diameter and fluid temperature, have been tested with design of experiments (DoE) to study the significance of the factors and interactions between them on cutting temperature. A 3-D finite element (FE) model has been developed to observe the effects of these factors on heat transfer rate. The simulation results show the most dominant factor to affect the cutting temperature is the temperature of the cooling fluid followed by the space between channel and tool insert internal wall.

Research on Relationship between Cutting Conditions and Chip Formation during End Milling of Aluminium Alloy 6061

This paper studied chip morphology in end milling of aluminium alloy 6061 by various cutting parameter such as feed rate, cutting speed and depth of cut. Slot milling operation were conducted. The analysis consists of chip morphology, chip weight, chip thickness and chip length. Scanning Electron Microscope (SEM) were used to obtain and examine the chips. Result shows that, end milling with higher cutting speed, feed rate and depth of cut generated short, small and light weigh of chips.

Study of Solvent Debinding Parameters for Metal Injection Moulded 316L Stainless Steel

Solvent debinding is one of a crucial stage in Metal Injection Moulding (MIM) process. This process begins with the removal of the soluble binder components by using solvents such as heptane or hexane. In solvent debinding process, unsuccessful to achieve maximum binder removal will cause a defect to the compact such as crack and swelling. So to have an optimum solvent debinding parameters are very important to improve the quality of the compact. Optimisation of solvent debinding process parameters for MIM of Stainless Steel 316L has been testified in this study. Gas atomised stainless steel 316L powder was mixed with a multicomponent binder in a twin blade mixer at a temperature of 150 °C for 90 minutes. The feedstock was successfully injected at the temperature of 150 °C. The green compacts were kept in n-heptane for eight different debinding times ranging between 30 to 240 minutes at temperatures of 40, 50, 60 and 70 °C to remove the primary binder components. From the result, the optimum temperature and time for solvent debinding were recorded at 60 °C and 240 minutes. Solvent debinding temperature and time give a significant effect on the rate of paraffin wax removal.

Progressive tool flank wear and surface roughness when turning AISI 1017 mild steel using reduced thickness inserts in finishing cutting conditions

Tool wear is a major aspect in metal cutting, especially during steel machining. This studies the capability of 1mm thick uncoated tungsten carbide insert during the turning of AISI 1017 mild steel. The reduction of insert thickness will lead to a more economical and efficient use of material and energy during fabrication, operation, and disposal of the cutting insert. Axial machining trials have been performed using the finishing cutting conditions. Tool flank wear and workpiece surface roughness were analysed using an optical microscope and contact perthometer device, respectively. The data of flank wear and surface roughness achieved were used to analyse the capability of replacing 4 mm thick cutting inserts with 1 mm thick cutting inserts. The results showed that the flank wear and the surface roughness of conventional inserts performed better as compared to the 1 mm thick insert with a significant difference of 5.74 % and 1.57 %. Thus, the experimental study shows that the 1 mm thick insert performed as good as a conventional cutting insert in terms of tool life and surface roughness quality.

Physical properties and microstructure study of stainless steel 316L alloy fabricated by selective laser melting

Selective Laser Melting (SLM) demonstrates the 21st century’s manufacturing infrastructure in which powdered raw material is melted by a high energy focused laser, and built up layer-by-layer until it forms three-dimensional metal parts. SLM process involves a variation of process parameters which affects the final material properties. 316L stainless steel compacts through the manipulation of building orientation and powder layer thickness parameters were manufactured by SLM. The effect of the manipulated parameters on the relative density and dimensional accuracy of the 316L stainless steel compacts, which were in the as-build condition, were experimented and analysed. The relationship between the microstructures and the physical properties of fabricated 316L stainless steel compacts was investigated in this study. The results revealed that 90° building orientation has higher relative density and dimensional accuracy than 0° building orientation. Building orientation was found to give more significant effect in terms of dimensional accuracy, and relative density of SLM compacts compare to build layer thickness. Nevertheless, the existence of large number and sizes of pores greatly influences the low performances of the density.

Implementation of Ant Colony Optimization Algorithm to Minimize Cost of Turning Process

In machining process, turning is one of process that were significantly change by introduction of computer numerical control (CNC). However, the process improvement is not stopping there, but the focused has change to reduce the machining cost. Improper parameter selection will caused vibration in cutting, unsecure workpiece, unappealing finishing and cost consuming. Therefore, the optimum parameter setting is required because it related to certain quality characteristics such as the unit production cost. This paper presents the study to minimize production cost for CNC turning process by using Ant Colony Optimization (ACO). The result shows that, the ACO was capable to search for optimum production cost in shorter time compare to other methods, including Genetic Algorithm.