N. Arunkumar

Multi-criteria supplier evaluation and selection using fuzzy AHP (alpha cut analysis): a case study

In todays competitive environment, an effective supplier selection process has a significant place in the success of manufacturing companies. Selecting the right suppliers help to reduce the purchasing cost and increase the competitiveness of the company. An analytical way to reach the best decision is more preferable in many business platforms. Analytical hierarchy process (AHP) is one of the best ways for deciding among the complex criteria structure in different levels. In this paper, a new method is presented to deal with the performance evaluation and selection of supplier for a manufacturing industry using fuzzy alpha cut analysis. It suggests the use of triangular fuzzy number to express the subjective preferences of evaluators. A usability evaluation of the AHP-based model with seven suppliers is discussed and a hypothetical supplier selection problem is solved. Fuzzy analytical hierarchy process (FAHP) is a new multi-criteria evaluation method evolved from Saatys AHP when there is fuzziness in the decision making. The results of this paper provide valuable suggestions to managers on the improvement needed with respect to each criterion when selecting suppliers.

Investigation on performance of abrasive water jet in machining hybrid composites

ABSTRACT For machining of composites, abrasive water jet machining is widely employed. For assembly of the machine tool structure, production of slots is essential. In this paper, abrasive water jet machining of composite laminates was experimentally investigated for various cutting parameters in terms of average surface roughness (Ra) and kerf taper (Kt). By generating a response surface model, the experimental values obtained for quality characteristics (Ra and Kt) were empirically related to cutting parameters. The effects of cutting parameters on quality characteristics were analyzed by utilizing empirical models and also optimized within the tested range based on desirability approach. The optimum parameter levels were also validated by confirmation test. From this investigation, it is evident that for obtaining a minimum kerf taper, traverse speed, water pressure, and abrasive mass flow rate are significant parameters and for obtaining less surface roughness traverse speed is the significant parameter.

Supplier evaluation and selection for a manufacturing industry using analytical hierarchy process – a case study

Supplier selection is one of the most critical activities of purchasing because of the key role of suppliers performance on cost, quality, delivery and service. Depending on the purchasing situation, the criteria have varying importance and there is a need to weight criteria. Practically in supplier selection problems, most of the input information is not known precisely. An analytical way to reach the best decision is more preferable in many such business platforms. Analytical hierarchy process (AHP) is one of the best ways for deciding among the complex criteria in different levels. AHP converts the qualitative factors of suppliers into quantitative measure reliably. This paper suggests the use of AHP, one of the strong methods in multi-criteria decision making to evaluate and select the supplier using criteria such as quality, cost, delivery, service, technology, capacity, reliability, lead-time and responsiveness. Here 9 attributes, 27 sub-attributes and 7 alternatives are evaluated to select the best among them. Case study on supplier selection for a leading textile machinery manufacturing industry in South India is presented in this paper.

EVOLUTIONARY APPROACH IN PROCESS IMPROVEMENT — A CASE STUDY IN AUTO ELECTRICAL ALTERNATOR MANUFACTURING

Evolution is understanding and overcoming current constraints in small steps toward optimum. Understanding requires elucidation of facts and corroborating theories that can explain those facts in a coherent manner. Overcoming requires self-development to suit the environment. In this paper, a case study about how a manufacturing process is improved in terms of productivity and quality using evolutionary improvements is explained. Here Understanding is achieved through use of Shainin Technique, PM analysis, Affinity Diagram, and the engineers ingenuity, along with Relations diagram. Overcoming is achieved through Geometrical Analysis and Designed Experiments. The Study has set a new benchmark in the Stator riveting process by proving it can yield the desired results, and the need to adapt welding process is avoided.

Effects of Micro and Nano-Size Al2O3 Particle Reinforcement on Mechanical Behaviour of Extruded Aluminum Alloy Matrix Composite

Aluminum alloy (AA2014) matrix composites reinforced by different weight percentage of aluminum oxide (Al2O3) in micro and nano sizes were fabricated through powder metallurgy route followed by hot extrusion process. Seven different aluminium composites with varying percentages of nano and micron sized alumina particles varying from 1% to 10% were evaluated in addition to monolithic alloy. The microstructure of nano-composite and monolithic alloys were examined by optical microscope and scanning electron microscope (SEM) equipped with an energy dispersive X-ray analysis (EDAX). In addition, the effects of weight fraction of the reinforcement matrix on mechanical properties were evaluated. The results have indicated that, a significant improvement in hardness of the nano composite was found in case of nano-composite with 8% of micro Al2O3 and 2% of nano Al2O3 particles by the addition of reinforcement.

Parametric optimization of deep-hole drilling on AISI 1045 steel and online tool condition monitoring using an accelerometer

ABSTRACT This paper aims at investigating the effects of the deep-hole drilling parameters such as cutting speed (Vc), feed rate (FR) (Fr), and coolant pressure (Cp) on the quality of the hole produced. The diameter and depth of the deep hole considered in the present work were 10 and 120 mm, respectively. In this study, hole quality was analyzed using surface roughness, cylindricity, and circularity characteristics. Coolant pressure and spindle speed play a vital role in determining the quality of the hole. During the drilling process, the fitness of the tool wear was observed by using an accelerometer. The experiments were conducted by varying the drilling parameters based on Taguchi’s Design of Experiment, and the output responses were measured and optimized using grey relation analysis. The results indicate a yield of the better surface finish from higher spindle speed, lower circularity, and cylindricity. Also, the tool wear was reduced by decreasing spindle speed. Based on the grey relational technique, optimal process parameter settings were found such as spindle speed of 2228 rpm, FR of 0.023 mm/rev, and coolant pressure of 30 kgf/cm2.

Evolution of Robust Manufacturing Process in Machining of DC Motor Commutator Using Complementing Problem Solving Tools

Machining the mica insulation in commutator to provide under cut in the surface of contact with the carbon brush is a vital process related to the life of the product. Complete removal of mica in the contact surface is essential and this requires complex sensing and positioning of the thin mica layer during machining. This study revealed improving the sensing and positioning technologies is not adequate and evolved a robust product-process design to overcome the real root cause of variations in the manufacturing process. Combined use of orthogonal array, Shainin technique, physical-mechanism analysis, relations-diagram and evaporating-cloud method complemented the problem solving approach in gaining knowledge and evolving robustness.

Evaluation of Flexural and Interlaminar Shear Strength of Laminated Hybrid Composites

The important material properties associated with laminated hybrid composites are the flexural and interlaminar shear strength (ILSS). These properties are relating the amount of bending and shear stress of a specific material will handle before individual plies fail. In this study the influence of stacking sequence on the flexural and interlaminar shear properties of the fabricated laminated hybrid composites, unidirectional carbon (UD) and bi-directional glass (BD) fabric /epoxy, has been investigated experimentally. The hybrid laminates were fabricated by hand lay-up technique with a total of 12 plies, by varying the position of carbon layers so as to obtain three different stacking sequences. The specimen preparation and the experimentations were carried out according to the ASTM standards. The result indicates by placing the carbon layers away from the neutral axis and at the neutral axis enhances the both flexural and interlaminar shear properties significantly. The failure modes of all specimens were investigated.

Studies on Mechanical Properties and Microstructure of Al2O3 Reinforced AA5083 Matrix Composite

The expectations over novel composite materials have been increased especially in automotive and aerospace applications due to its superior weight to strength ratio and tailored mechanical properties. In this frame work, aluminum alloy AA5083 alloy matrix reinforced with micron (10% wt – 5% wt) and nanoparticles (1% wt – 5% wt) of Al2O3. The composite samples were fabricated through powder metallurgy route. Optimum amount of reinforcement were determined by evaluating mechanical properties like micro-hardness and compressive strength of composites. The characterizations were probed by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) methods. The results reveal that the composites containing 2% wt of nanoAl2O3 and 8 % micro Al2O3 reinforcement witnessed superior mechanical properties due to its combined effect of concentration and particulate scale and the great isotropic behavior was achieved by homogenous dispersion of reinforcement in the matrix phase.