Behzad Ghodrati

Reliability and operating environment-based spare parts estimation approach : a case study in Kiruna Mine, Sweden

Purpose – With continuous technological development in the twenty‐first century, the industry and industrial systems have become complex and making their availability more critical. In this context, the product support and its related issues such as spare parts play an important role. Lack of timely or incomplete support, such as the lack of spare parts when required, is likely to cause unexpected downtimes, which in turn often lead to incompensatable losses. Therefore the importance of predicting the correct support to keep the system functionally available needs to be emphasized. Required number of spare parts could be obtained based on technical and life parameters. This paper seeks to examine the system reliability and operating environment, which are the two parameters to be considered in this article.Design/methodology/approach – A model is provided in this paper to determine the number of required spare parts with respect to the effect of the external factors, except time, on the reliability charac...

Operating environment-based spare parts forecasting and logistics : a case study

In today’s highly dynamic and constantly changing industrial environment, issues relating to product support are becoming increasingly important. However, the extent of attention given to these issues varies considerably depending on the perspective of the interested person or profession. These are likely to vary from design engineers at the conceptual stages of product development to manufacturers and users in the latter stages. Additionally, the make up a particular product support package varies according to type of system/mission, application and stages of machine/system life. The lack of timely or incomplete support is likely to cause unexpected downtimes, which in turn will lead to losses for which one is unable to compensate. Falling within the definition of product support items are spare parts. The lack of a critical spare part can cause untimely stoppage of machine/system. Forecasting of product support and spare parts requirements based on reliability and maintainability (R&M) characteristics of system/components together with system operating environment(s) is one of the most effective strategies for prevention of unplanned stoppages. In this paper the effects of environmental factors on hydraulic brake pump used in mine loaders are presented and analysed. The reliability of this non-repairable part and its operational impact are assessed for both when the environmental factors are considered and when they are ignored. From the study, it is found that the forecasting for brake pump inventory is more accurate when environmental factors are included in the calculations. These results demonstrate the value of the inclusion of environmental factors data in the product support logistics’ optimisation process.

Reliability analysis of drum shearer machine at mechanized longwall mines

Purpose – Longwall mining is a special mining method with high productivity and smooth operation and the drum shearer is known as the most important component in longwall mines due to its direct role in the coal cutting and production process. Therefore, its reliability is important in keeping the mine production at a desired level. Hence, reliability analysis is essential in identifying and removing existing problems of this machine in order to achieve a better production condition. This paper seeks to learn about the reliability of the shearer machine in order to locate critical subsystems. The improvement of the reliability of the critical subsystems, to enhance the optimum operation of the shearer machine, is the main objective of this research.Design/methodology/approach – A basic methodology was used in this paper for the reliability modeling of the shearer machine. First, failure and performance data from a two‐year period at the Tabas Coal Mine‐Iran was classified and sorted. The tests for validat...

Product support improvement by considering system operating environment : a case study on spare parts procurement

Purpose – The ongoing availability of existing industrial systems/machines depends to a great extent on the form and level of product support. Product support, or the after sale service of a product, is important because it assures the expected function of the product in its operational phase. Product support is affected by a number of factors, including system reliability and maintainability characteristics and the operating environment. The purpose of this paper is to analyze the influence of time independent external factors of industrial systems on product support requirements and spare parts need.Design/methodology/approach – This paper, after discussing the factors influencing product support, describes a method to estimate spare part requirements based on estimation of the actual reliability of a product under the influence of the product‐operating environment using a proportional hazard model. A spare parts estimation software, Spare Management Software (SMS), is used to check the results. Then a ...

Spare parts estimation and risk assessment conducted at Choghart Iron Ore Mine: A case study

Purpose – Spare parts needs are dependent on the characteristics of the product in question, e.g. its reliability and maintainability, and the characteristics of the environment in which the produc ...

Reliability analysis of the cable system of drum shearer using the power law process model

In this article, the reliability of the cable system of a drum shearer machine was studied and analysed using operation and maintenance data from an Iranian mine for a period of two years. The tests for trend and serial correlation show that the times between successive failures for the cable system are not independent and identically distributed. A goodness-of-fit test shows that the power law process model provides a good fit to the failure data of this system. After parameter estimation for the power law model, reliability and failure rate plots were obtained. Based on analysis and results, a period of 125 h was defined as the reliability-based maintenance interval for the cable system of the shearer. The analysis shows that, by using this strategy, the reliability of the system will improve by at least 50%.

Downtime analysis of drilling machines and suggestions for improvements

Purpose – The purpose of this paper is to analyse and compare the downtime of four drilling machines used in two underground mines in Sweden. The downtime of these machines was compared to show what problems affect downtime and which strategies should be applied to reduce it. Design/methodology/approach – The study collects failure data from a two-year period for four drilling machines and performs reliability analysis. It also performs downtime analysis utilising a log-log diagram with a confidence interval. Findings – There are notable differences in the downtime of most of the studied components for all machines. The hoses and feeder have relatively high downtime. Depending on their downtime, the significant components can be ranked in three groups. The downtime of the studied components is due to reliability problems. The study suggests the need to improve the reliability of critical components to reduce the downtime of drilling machines. Originality/value – The method of analysing the downtime, ident...

Reliability and spare parts estimation taking into consideration the operational environment — A case study

Spare parts provision is a complex problem and requires an accurate model to analysis all factors that may affect the required number of spare parts. The number of spare parts required can be effectively estimated based on the reliability performance of the item. The reliability characteristics of an item are influenced not only by the operating time, but also by factors such as the operational environment. Therefore, for spare parts provisioning to be effective, the impact of these influence factors on the reliability performance of the item should be quantified. Hence, the statistical approach selected for reliability performance analysis must be able to handle the effect of these factors. One of the important models for reliability performance analysis that takes influence factors into account is the proportional hazard model (PHM), which has received less attention in the field of spare parts provisioning. In this paper the application of PHM to spare parts provision is discussed and demonstrated by a case study.

AN APPROACH FOR RISK ASSESSMENT OF RAIL DEFECTS

Rail defects appear in a greater variety and frequency due to higher axle loads and increasing traffic density in passenger and freight trains. Many of these rail defects, if left undetected, can develop into rail breaks, which may lead to train derailments. Reduction in the number of such catastrophic events requires huge investments on inspection and maintenance activities. Therefore proper maintenance planning and risk assessment is required to reduce the rail maintenance cost without compromising safety. In this paper, an approach has been developed for risk assessment of rail defects to support the decision-making process during scheduling of rail inspection and grinding frequency, based on the type of defect and its risk of occurring and developing into a rail break. The approach will help in increasing the safety of passengers and rolling stock as well as reducing the overall rail maintenance cost, as it helps in making effective decisions related to inspection frequency (i.e. resource allocation according to the need). The approach is presented with the aid of a case study from the Swedish National Rail Administration (Banverket). Both, quantitative and qualitative analysis technique has been used in this paper to assess the risk of occurrence of a rail defect and its development into a rail break.

Activity-based life cycle cost analysis as an alternative to conventional LCC in engineering design

Petroleum exploration and production in the Arctic region is becoming of increasing interest as the world needs more energy. However, since there is little experience and data on Arctic oil and gas production, the design of production facilities and equipment to be used in the Arctic region is fraught with high cost and risk. Conventional life cycle costing (LCC) approaches have been discussed in literature for many years, but it is difficult to perform such analysis due to the need for a large amount of data and the inherent uncertainty in the results. There is also little evidence in the literature on the practical usage of LCC. In this paper we discuss the differences between conventional LCC and activity-based LCC (AB-LCC) cost systems. Moreover, based on an analytical comparison between the two methodologies we find that the AB-LCC methodology may be a better alternative to use for cost analysis in the design of production facilities to be used in unfamiliar environments such as the Arctic. A simple example is used to demonstrate the differences between conventional LCC and AB-LCC analysis.