A Study on The Influence of Nd-Magnets On The Electrical Discharge Machining Surface Quality of Mild Steel

Electrical discharge machining (EDM) is one of the processing methods based on non-traditional manufacturing procedures. It is gaining increased popularity, since it does not require cutting tools and allows machining of hard, brittle and intricate geometries. In recent years, EDM researchers have explored a number of ways to improve the surface state of work pieces machined using EDM. In the present paper, roughness value of work pieces machined under the influence of varied magnetic intensities, peak current and pulse durations is investigated. A new laboratory setup, incorporating Nd-magnets, is created to carry out the experiments together with a TOOLCRAFT A25 EDM. Empirical modeling has been carried out to establish a mathematical relationship between the roughness and the machining parameters. Optimum settings have been identified that produce lowest roughness values. Results indicated that the presence of a magnetic field in the spark gap region increases the surface roughness of the machined work piece. Surface roughness of work piece was also noted to be highly influenced by current and pulse on-time. Higher values of these parameters increased surface roughness. Low magnetic intensity, lower current, lower pulse-on time and relatively higher pulse pause time produced a better surface finish. Keywords: Electric discharge machining (EDM); surface roughness

Effects of Clearance Size on the Dynamic Response of Planar Multi-body Systems with Differently Located Frictionless Revolute Clearance Joints

This paper numerically investigates the effects of clearance size of differently located revolute clearance joints without friction on the overall dynamic characteristics of a multi-body system. A typical planar slider-crank mechanism is used as a demonstration case in which the effects of clearance size of a revolute clearance joint between the crank and connecting rod (c-cr), and between the connecting rod and slider (s-cr) are separately investigated with comprehensive observations numerically presented. It is observed that, different joints in a multi-body system have different sensitivities to the clearance size. Therefore the dynamic behavior of one clearance revolute joint cannot be used as a general case for a mechanical system. Also the location of the clearance revolute joint and the clearance size play a crucial role in predicting accurately the dynamic responses of the system. Keywords: Chaotic behavior, Contact-impact force, Dynamic response, Multi-body mechanical system, Periodic behavior, Poincare Map, Quasi-periodic behavior, revolute clearance joint

Dynamic Modeling of Chatter Vibration in Cylindrical Plunge Grinding Process

Cylindrical plunge grinding process is a machining process normally employed as a final stage in precision machining of shafts and sleeves. The occurrence of chatter vibrations in cylindrical plunge grinding limits the ability of the grinding process to achieve the desired accuracy and surface finish. Moreover, chatter vibration leads to high costs of production due to tool breakages. In this paper, a theoretical model for the prediction of chatter vibration in cylindrical grinding is developed. The model is based on the geometric and dynamic interaction of the work piece and the grinding wheel. The model is validated with a series of experiments. Results show that variation in the grinding wheel and work piece speeds, and in-feed lead to changes in the vibration modes and amplitudes of vibration

Key performance indicators for manufacturing safety in paint manufacturing: A case of kenyan industry.

Manufacturing safety is a key priority in the success of any business, as it can affect both the present and future competitive position of an organization. Organizations must measure safety in order to find areas of weakness, and then implement actions aimed at raising safety levels. Industrial accidents in the chemical industry indicate a need for both leading and lagging indicators of safety in the workplace. The purpose of this study was to formulate and validate a set of key performance indicators that can be used in the measurement and reporting of manufacturing safety, and ensure a safe working environment for the workers on a continuous basis. The results consisted of 21 Key Performance Indicators (KPIs), with fire safety being the most relevant KPI. The information gathered during a manufacturing safety performance measurement exercise can be used to implement activities directed towards reducing the level of worker exposure to health and safety risks within the facto