A fractional factorial design has been used to explore the variables that affect microwave dissolution using perfluoroalkoxy (PFA)-Teflon digestion vessels. Optimum operating conditions for National Research Council of Canada, certified reference material TORT-I Lobster Hepatopancreas and National Institute of Standards and Technology, Standard Reference Material (SRM) 1575 Pine Needles, were obtained using this procedure. The optimum conditions found for each variable are: 0.25 g sample mass, 6 ml of concentrated hydrochloric acid, 6 ml of concentrated nitric acid, 3 ml of concentrated hydrofluoric acid and 90% microwave power for a total dissolution time of 15 min. Results for Ca, Fe, Cu and Zn in TORT-I and Ca and Fe in SRM 1575 were in agreement with the certified values.
Metal matrix composite is composite material that combines the metallic properties of matrix alloys and additional element to reinforce the product. This paper evaluates the machining performance of uncoated carbide and coated carbide in terms of surface integrity during end milling of LM6 aluminium MMC. The parameter of cutting speed, feed rate and axial depth of cut were kept constant at 3000 rpm spindle speed, 60 mm/min feed rate and 0.5 axial dept of cut. The radial depth of cut were varied from 0.01mm to 0.1 mm. The results indicated that uncoated carbide show the better performance in terms of surface roughness and surface profile, as compared to coated carbide. On the other hand, coated carbide cutting tools suffered with built-up-edge formation at the tool edge, hence caused shearing effect and deterioration at the tool-chip interface. This study is expected to provide understanding of machining metal matrix composites based materials.
This study was carried out to investigate how the high-speed milling of Inconel 718 using ball nose end mill could enhance the productivity and quality of the finish parts. The experimental work was carried out through Response Surface Methodology via Box-Behnken design. The effect of prominent milling parameters, namely cutting speed, feed rate, depth of cut (DOC), and width of cut (WOC) were studied to evaluate their effects on tool life, surface roughness and cutting force. In this study, the cutting speed, feed rate, DOC, and WOC were in the range of 100 - 140 m/min, 0.1 - 0.2 mm/tooth, 0.5 - 1.0 mm and 0.2 - 1.8 mm, respectively. In order to reduce the effect of heat generated during the high speed milling operation, minimum quantity lubrication of 50 ml/hr was used. The effect of input factors on the responds was identified by mean of ANOVA. The response of tool life, surface roughness and cutting force together with calculated material removal rate were then simultaneously optimized and further described by perturbation graph. Interaction between WOC with other factors was found to be the most dominating factor of all responds. The optimum cutting parameter which obtained the longest tool life of 60 mins, minimum surface roughness of 0.262 μm and resultant force of 221 N was at cutting speed of 100 m/min, feed rate of 0.15 mm/tooth, DOC 0.5 m and WOC 0.66 mm.
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. IntroductionBrass is one of the electrical conductive materials. Today, however, brass is seldom used as an electrode in EDM die sinking due to its high wear rate but it still good for machining materials for high speed small hole machines because it exhibits higher degree of stiffness and easier to machine than copper [1]. Even though, brass already used as an electrode but it is still not tested for cutting aluminium alloys LM6. It is known that LM6 which aluminium containing 12% silicon has good resistance to corrosion and excellent cast ability [2]. It is widely used in many fabrication devices due to its characteristics properties such as applications for motor housings, manifolds, marine components and pumping cases. Further, LM6 is also appropriate where sometimes castings require to be welded.Usually in die tooling, when materials used is hard, it becomes better for die tooling, however it would be difficult to cutting using conventional cutting tools [3]. Therefore, some others electrode materials were tested against the aluminium alloys LM6 like copper tungsten [4], copper [5] and graphite [6] which has yielded a good experimental result. A special advantage of EDM die-sinking offers compared to conventional machine where materials removed without any contact between electrode and workpiece. As a result, problems of vibration and mechanical stress can be eliminated during machining process [7].Even though, the use of die-sinking EDM focused on the cutting material having conductivity of an electric, the process capability of cutting alloys materials, becomes more challenges regardless of their hardness and toughness [8]. The most advantage of EDM die-sinking machine is that it can cut electrical conductivity material, free from burrs especially for stamping die that can be produced by EDM die-sinking with accurate dimension, low cost and fast processes [9].
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