The reduction of the shutdown maintenance cost, frequency and the loss in production by the proper assessment of the scope of shutdown maintenance work

The reduction of the shutdown maintenance cost, the shutdown maintenance frequency and the loss in production that occurs as a result of performing shutdown maintenance whilst maintaining shutdown maintenance purpose and without creating any operational, safety, or economic problems during normal operation represents one of the most important issues that supports the overall strategy in the continuous process industries. The importance of this issue stimulated the work in research to find ways and methods to reduce the cost and frequency of shutdown maintenance, in addition to, the loss in production without increasing the number of the unplanned shutdowns or creating interruptions to the production line. [Continues.

A New Association Analysis-Based Method for Enhancing Maintenance and Repair in Manufacturing

Maintenance and quality of products are absolutely crucial for any organization to succeed in the industrial and manufacturing engineering. Current research studies have confirmed the presence of a high correlation between these two factors, namely maintenance and quality of products, in industrial organizations. Nevertheless, no extensive research has been conducted in order to study the link between maintenance and the quality of products in manufacturing. In this paper, we conduct a study in this domain and examine the relationship patterns between maintenance and the quality of product using manufacturing data on maintenance and the product quality. Specifically, we employ association analysis and association rule mining with large and extensive sets of product quality, repair, and maintenance data. Our main objective is to discover interesting and non-trivial associations for feature failure resulting in the repair or maintenance of a product with unapproved quality. The results of evaluation are quite interesting. The resulting association rules with high values of confidence and lift suggest some essential associations between the product features and the failure; such findings have not been known and used before. This can help quality engineers and maintenance teams to enhance maintenance and repair operations and lower the overall cost of manufacturing

A Model for Maintenance Planning and Process Quality Control Optimization Based on EWMA and CUSUM Control Charts

The performance of a production system is highly dependent on the smooth operation of various equipment and processes. Thus, reducing failures of the equipment and processes in a cost-effective manner improves overall performance; this is often achieved by carrying out maintenance and quality control policies. In this study, an integrated optimization method that addresses both maintenance strategies and quality control practices is proposed using an exponentially weighted moving average (EWMA) chart, in which both corrective and preventive maintenance policies are considered. The integrated model has been proposed to find optimal decision variables of both the process quality decision parameters and the optimal interval of preventive maintenance (i.e., Ns, Hs, L, λ, and t_PM) to result in overall optimal expected hourly total system costs. A case study is then utilized to investigate the impact of cost criteria on the proposed integrated model and to compare the proposed model with a model using the cumulative sum (CUSUM) control chart. The improved model outputs indicate that there is a reduction of 34.6% in the total expected costs compared with those of the other model using the CUSUM chart. Finally, an analysis of sensitivity to present the effectiveness of the model parameters and the main variables in the overall costs of the system is provided

Studying the Effect of Process Parameters on Part Depth in Single Point Incremental Forming of AA1050-H14 Aluminum Alloy Sheets

Single Point Incremental Forming (SPIF) is an innovative forming approach for sheet metal that promises an inexpensive and flexible way to produce sheet metal parts in small batches. SPIF allows the production of complex geometries using a computer numerical control machine. In this study, SPIF has been conducted to investigate the effects of sheet thickness, tool diameter, feed rate, and step size on part depth. Statistical tools were used to design the experiments. Analysis of variance, as well as regression and optimization techniques were used to analyze the resulting part depth. Two levels of each parameter were included in a full factorial design. The study found several relations amongst the process parameters and the part depth. In summary, it was proved that the sheet thickness and tool diameter have the greatest effect on the part depth, whereas the step size has a small, but significant one

Structural model of factors contributing to the motivational problem of taking shortcuts at construction workplaces in the Kingdom of Saudi Arabia

An unsafe act is a type of work that involves some risk. Since more than a decade, unsafe act has accounted as a foremost cause of work-related accident, especially in the field of construction. Several attempts have been made to reduce the causes of unsafe acts; however, shortcut, which is a notable type of unsafe act, has received little attention in previous works, even though some of causal effects have been attributed to this habit. This paper aims to reveal an unexplained proportion that can be explained by different underlying causes of motivational problems to shortcuts rather than by habit. Accordingly, two structural models have been proposed based on quantitative and qualitative data from previous reviews associated with the effects on negative feeling and thinking on risk management. These models were tested using on Exploratory Factor analysis (EFA) and Confirmatory Factor Analysis (CFA) on data collected from a cross-section survey conducted at construction sites in largest cities within the Kingdom of Saudi Arabia (KSA), where large number of accidents in these cities occurred. Data of 204 respondents of the mailed questionnaires were analyzed after screening all responses. Statistical Package for Social Sciences (SPSS) (version 22) was used to test for Structural Equation Model (SEM) assumptions. The developed hypotheses were tested and model with the best fit was identified. Findings revealed that 45%–55% of the motivational problems to shortcuts were explained by the selected structural model

Studying and Optimizing the Effect of Process Parameters on Machining Vibration in Turning Process of AISI 1040 Steel

The turning, which consists of the removal of metal from the outer diameter of a rotating cylindrical workpiece, is one of the most common techniques for cutting, especially when finishing the product. The values of the cutting parameters, such as feed rate, cutting speed, and depth of cut, in a turning operation must be selected carefully to improve the profit of operations by enhancing productivity and reducing the total manufacturing cost for each component. A high vibration leads to poor surface finish and reduced productivity and shortens the tool life; therefore, this parameter should be controlled. In this study, an experiment is conducted to investigate the effects of these cutting parameters in the turning process of a workpiece, composed of AISI 1040 steel, using the response surface method. Statistical tools were used to design the experiments. These parameters are optimized by using analysis of variance, regression, and optimization techniques to achieve the condition of minimum vibration and chip frequency, therefore improving the surface roughness after the turning process

Design and Validation of a Reduced Switching Components Step-Up Multilevel Inverter (RSCS-MLI)

A reduced switching components step-up multilevel inverter (RSCS-MLI) is presented in the paper. The basic circuit of the proposed MLI can produce 11 levels in the output voltage with a reduced number of switching components. The other features of the proposed circuit include a low value of voltage stresses and the inherent generation of the voltage levels pertaining to the negative half without the requirement of an H-bridge. Fundamental frequency switching technique, also known as Nearest Level Control (NLC) technique, is implemented in the proposed topology for generating the switching signals. The experimental total harmonic distortion (THD) in the output voltage comes out to be 9.4% for modulation index equal to 1. Based on different parameters, a comparative study has been shown in the paper, which makes the claim of the proposed MLI stronger. An experimental setup is prepared to carry out the hardware implementation of the proposed structure and monitor its performance under dynamic load conditions, which is also used to verify the simulation results. Power loss analysis, carried out by using PLECS software, helps us to gain insight into different losses occurring while operating the inverter. The different results are explained and analyzed in the paper