Abstract: Tailored welded blank (TWB) consists of steel sheets of different thicknesses and strength which welded into one sheet to reduce weight and production costs, to increase dimensional accuracy and strength. Since a tailored blank is composed of different sheets of metals having different thicknesses and properties, the forming of tailored blanks then creates a lot of technical problems especially in the scheme of deformation. The objective of this work was to evaluate the drawability of tailored blanks. In order to assess the forming behavior of the tailor-welded blanks under the influence of weld orientations, a finite element and experimental methods were conducted. Three welded specimens with weld lines oriented at an angle of 0°, 90° and 45° with respect to the direction of load were investigated. The finite element result showed in a good agreement with the experimental result. The result of the experiment showed that a welded part was characterized by a higher strength and lower plasticity compared to those of the base material. Hence, the weld influences the strain distribution of the tailor-welded specimens. This phenomenon depends strongly on the direction of the weld against the direction of tensile load. The lowest strains occur in the specimen with a longitudinal weld.
Abstract: Chip formation is a dynamic process that is often nonlinear in nature. A chip may not form when the depth of cut is less than a minimum chip thickness. It is aimed to investigate influence of depth of cut on contact phenomenon in micromachining. This paper presents a series of simulation works by finite element method on depth of cut effect on micromachining. A model is developed with consideration of the Johnson-Cook material and Arbitrary Lagrangian–Eulerian (ALE) method. In this work investigate the effect of depth of cut on the contact phenomenon during micromachining AISI D2. The results of the analysis are showed in aspects of interrelationship between material separation and frictional shear contact, distribution of stick-slide regions and contact stress on the work piece and cutting tool. It is found that the sticking and sliding was occurred on three zones as primary, secondary and tertiary shear zone. The contact phenomena can be showed around the tool edge radius where material flows around it and piles in front of the cutting tool through material separation. The investigation of contact phenomena inclusive under three criteria such as a/r < 1, a/r > 1 and a/r = 1 on positive rake angle.
Abstract: Conventional coolant/lubricants have some drawbacks such as high cost, pollution, and unsatisfactory product quality. New cooling approach by using gases to enhance machinability has been investigated. This study presents the finding of nitrogen gas and nitrogen-oil-mist as conditions when turning of hardened stainless tool steel (STAVAX ESR) with hardness 48 HRC. Turning experiments were carried out on CNC turning machine using rhomboid type wiper coated carbide cutting inserts. The result show that better product surface finish and longer tool life, as well as decrease cutting temperatures could be achieved by using nitrogen-oil-mist condition compared to nitrogen gas condition.
Abstract: Minimum quantity lubrication (MQL) or as it’s called semi dry cutting is a technique which spray a small value of lubricant flow rate to the cutting zone area. MQL has been used in many machining process with different cutting tools and workpiece materials due to its green environments and economically advantageous. MQL has become an attractive option to dry and flood cutting in terms of reduce the temperature in the cutting zone and reduce the cost of the product. However, in MQL seems to be machining limited by cutting temperature, because at high speed the effect of oil mist becomes evaporated. Therefore another alternative cooling approach was used with oil mist in this research. This research presents study the performance of nitrogen gas as a coolant and oil mist as lubricant in turning of hardened stainless tool steel (STAVAX ESR) with hardness 48 HRC. Using a gas as coolant with oil mist is a new solution for enhancing machinability. Turning experiments are carried out on CNC turning machine. The cutting insert grade is KC5010 (PVD-TiAlN wiper coated carbide). The experimental results were: 1) nitrogen gas with oil mist prolongs tool life compare with air with oil mist. 2) better product surface finish by using nitrogen gas with oil mist.
Abstract: Nowadays micro fabrication technology is very varied and being continuously developed. One of them uses bacteria as tools that known as biomachining. Acidithiobacillus ferooxidans is a one of bacteria which can do metal removal as a source of energy. The previous research has proven the ability of Acidithiobacillus ferooxidans for material removal process. In this research, biomachining process was added by angle of inclination parameter to know the effect on copper surface profile and roughness. This method was used to get profile shape result of multi-axis in biomachining. Workpieces were patterned by photolithography method and put in the bacterial culture medium, which was inclined 20° and 30° on inclinator. Profile shape and the surface roughness measurement data were taken by SURFCOM machine. The results of this research showed that by inclining 20° and 30° of biomachining sample produced different profile shapes and surface roughness.
Abstract: 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.
Abstract: Injection molding usually uses to produce part from plastic. Other than it is cheap, it also can produce part in large quantity. In this paper, Taguchi Methods was used to define the optimization of process parameter for an injection molding machine to produce a dumbbell product from High-density Polyethylene (HDPE) + natural fiber (Kenaf). Taguchi Methods with L9-34 approaches will be used in this work. Four different formulation of material will be tested to find the best formulation and its parameter setting. Here, an orthogonal array (OA), signal-to-noise (S/N) ratio and analysis of variance (ANOVA) are employed to analyze the effect of injection molding parameter. The significant of formulation and parameter setting from injection molding through the hardness and the strength value of the specimen. Furthermore, test will be conducted through hardness test and tensile test. Changes in the parameter setting will give different hardness and tensile strength value. The optimum parameter setting was set base on the S/N ratio. For each formulation, it has their optimum parameter setting for hardness and for tensile strength. The optimum parameter setting was predicting their S/N ratio using Minitab software.
Abstract: Influence of sewage ratio or Fat Oil Grease (FOG) on the feedstock rheological characteristic for optimal binder formulation in metal injection moulding is evaluated besides Polypropylene (PP) as a backbone binder. Powder loading of 62% of water atomised SS316L being used here to determine the possibility of the best binder formulation which could be optimised for optimal powder loading base on rheological characteristic analysis. Two binder formulations of PP to SF being selected here are 60/40, 50/50 and 40/60 accordingly with the powder loading of 62% each binder formulation. The analysis will be base on viscosity, shear rate, temperature, activation energy, flow behaviour index and moldability index. It is found that from rheological result views, binder with composition of 60/40 and 50/50 exhibit pseudoplastic behaviour or shear thinning where the viscosity decrease with increasing shear rate. For 40/60 binder ratio is not suitable since the behaviour of the flow indicates dilatants behaviour. After considering all the criteria in terms of flow behaviour index, activation energy, viscosity and mouldability index, binder with ratio of 60/40 is evolve as a good selections.
Abstract: This paper investigates the performance of brass electrode on the removal of aluminium alloys LM6 (Al-Sil2) in an electrical discharge machining (EDM) die-sinking. The machining parameters such as pulse-on time, pulse-off time and peak current were selected to find the responses on the material characteristics such as material removal rate (MRR), electrode wear rate (EWR) and surface roughness (Ra). Brass with diameter of 10mm was chosen as an electrode. Orthogonal array of Taguchi method was used to develop experimental matrix and to optimize the MRR, EWR and Ra. It is found that the current is the most significantly affected the MRR, EWR and Ra while pulse on time, pulse off time and voltage are less significant factor that affected the responses. Percentage optimum value of MRR increases to 3.99%, however EWR and Ra reduce to 3.10% and 2.48% respectively. Thus, it shows that brass having capability to cut aluminium alloys LM6.