Quality Of Spare Parts Research Articles

A general inspection and replacement policy for protection systems subject to shocks with state dependent effect

This paper proposes a new maintenance policy for protection systems which fail due to competing causes: internal deterioration and fatal external shocks. The study is motivated by a real problem in a power distribution company, in which a circuit breaker is designed to protect an electrical network from critical events such as overloads and short circuits. The failure of the system is hidden and can lead to a disaster if it is not replaced before a demand is received. So, to improve its readiness, we have developed a new two-phase (inspection & replacement) policy for a protection system with a heterogeneous population. Heterogeneity reflects factors such as variability in the quality of spare parts or in the installation of the components, which can be poorly or properly executed, resulting in some having a short life, while others may achieve a long life. Inspections are imperfect, which induces misclassification. The deterioration process is modeled via the delay-time concept. Furthermore, the shock rate depends upon the state of the system and follows a non-homogeneous Poisson process. Thus, using a numerical approach, the objective of this study is to determine the number of inspections during the first phase, the interval between consecutive inspections, and the age for scheduled preventive replacement. We compared this policy to two other classical policies via a case study and found that it has significant cost-saving potential. Generally, our results indicate when inspections should be prioritized over age-preventive replacement, and vice versa. Multi-phase policies are particularly effective for components with different characteristic lives, with inspections being crucial for maintaining readiness, often requiring investment in quality assurance to prevent misclassification. Conversely, age-based policies are more advantageous for strong (long-lived) components or when the probability of misclassification is high.

УПРАВЛЕНИЕ РЕЗЕРВАМИ ЗАПЧАСТЕЙ В МНОГОУРОВНЕВОЙ СТРУКТУРЕ ОБЕСПЕЧЕНИЯ НАДЕЖНОСТИ ТЕХНИЧЕСКИХ СИСТЕМ

The processes occurring in production systems are limited by agrotechnical requirements. The determining factor of the technological reliability of the system is the time of replacement of the failed element. The reliability of the system depends significantly on the ratio between the time of replacement of the failed element with a workable spare part and the allowable downtime in the operation of the production system. A set of spare parts and accessories should be considered as a kind of unloaded reserve. (Research purpose) The research purpose is formalizing the dependencies between the performance indicators of the spare parts supply system and optimizing the flow of applications for spare parts, taking into account their quality. (Materials and methods) It was noted that in order to assess the quality of spare parts and accessories on a certain date, it is advisable to fix three parts of the purchased batch of spare parts. The task of assessing the reliability of spare parts and accessories at an early stage of their use was formulated. (Results and discussion) It was found that for a batch of spare parts and accessories of poor quality, it is possible to make prompt decisions on complaints to the manufacturer of spare parts and their replacement. (Conclusions) It was stated that the processes of spending spare parts are stochastic. It was established that a set of spare parts and accessories is a kind of resource designed to improve the reliability of the functioning of technical systems. The availability factor of spare parts and accessories was proposed, taking into account the intensity of their failures during storage. The general reliability model should take into account: the strategy of replenishment of spare parts, the type of structure of the supply system, the type of failure model. Proved that the strategy of continuous replenishment of spare parts and accessories is effective. It provides, other things being equal, a higher value of the availability factor of spare parts and accessories.

Evaluation of Centrifugal Pump Availability Trends and Analysis

Centrifugal pumps are essential elements in industrial systems, facilitating fluid transfer and pressure generation across various applications. This study explores the vital task of evaluating centrifugal pump availability trends, focusing on three United Pumps crude delivery centrifugal pumps (P-90A, P-90B, and P-90C) over a span of seven years (2009-2015). With the use of derived equations and annual run-hours data from the facility's operations and maintenance database, the study ascertained the availability of the pumps. The findings and analysis showed that pumps P-90A and P-90B had significant decline in availability over the evaluation period (2009-2015), with P-90A finally failing in 2014. P-90C on the other hand, demonstrated relatively higher availability levels even though it was trending downward. The main cause of the decline in availability is attributed to the Original Equipment Manufacturers' decision to discontinue production of the pump model and its spares, which led to the substitution of locally made components for OEM parts. The study highlights the critical role, OEM support and its genuine spare parts play in optimising pump availability, reliability, and continuous operation—all of which prolong the pump's operating lifespan. It suggests improved methods, regular inspections, preventive maintenance, re-evaluating the quality of spare parts, and investigating replacement options. The study provides recommendations for improving pumping station performance and efficiency, based on empirical data and analysis, to industry stakeholders involved in crude oil delivery operations.

Joint Decisions of Components Replacement and Spare Parts Ordering Considering Different Supplied Product Quality

In addition to equipment maintenance decisions, spare parts ordering decisions from different suppliers play a key role in reducing related costs (e.g., maintenance, inventory and ordering costs). Since suppliers may use different production technologies and materials, spare parts (or products) from different suppliers can be different in quality. Nevertheless, in recent studies, the quality of spare parts is rarely considered to incorporate both equipment maintenance and spare parts ordering. In this paper, we investigate the joint optimization of condition-based maintenance and spare parts provisioning policy under two suppliers with different product quality. We formulate a sequential-decision problem with a Markov decision process and consequently obtain an optimal maintenance and ordering policy by an exact value iteration algorithm. To improve computation efficiency, based on the principle of sequential optimization, we develop heuristic methods. Extensive numerical experiments are conducted to assess the overall performance of the developed heuristic methods. Compared to the optimal method, results showed that the average cost gap is about 2% and computation time is reduced by 94% on average under the proposed heuristic method. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This paper is motivated by the observation that automobile industries tried to integrate emergency suppliers from which spare parts have different quality into maintenance schedules to avoid stockout and reduce equipment failure during the Covid-19 pandemic. Specifically, the article focuses on balancing the trade-offs between condition-based maintenance and inventory management from two suppliers with different lead times and spare parts quality for multi-unit systems. On the one hand, effective maintenance scheduling relies on spare parts for replacement to ensure the stability of production. On the other hand, inventory management needs to select the supplier with appropriate lead time and product quality to reduce the ordering cost and avoid stockout based on the degradation states of equipment. The joint optimization of these two aspects serves to reduce the total maintenance and ordering cost. Nevertheless, most existing research aims to optimize them separately. In this paper, we formulate the joint decision problem considering the two aspects based on a Markov decision process. We obtain an optimal maintenance and ordering policy by an exact value iteration algorithm and present heuristics to improve the computation efficiency when the system contains multiple machines. Practitioners can implement the proposed methodology to make condition-based maintenance and inventory management when spare parts with different qualities are ordered from two suppliers. To balance cost and computational efficiency, it is suggested to implement the optimal policy by an exact value iteration algorithm when the number of machines is small in the system and use the heuristic methods when the number of machines is large (i.e., usually larger than 3).

Methodology for determining effect of starting modes of internal combustion engine on change in engine performance characteristics

Introduction. As part of solving the urgent problem of forecasting technical impacts and residual life depending on operating time, a method for determining the effect of the starting mode on a change in the structural parameter determining reliability is presented. The essence of this technique and its novelty consists in combining two full-factor experiments to determine the effect of operating conditions on changes in the structural parameters of the engine. The purpose of the scientific study is to determine the effect of the starting internal combustion engine on the change in the performance characteristics of the engine.The novelty of the article lies in the combination of two full-factor experiments to determine the effect of operating conditions on changes in the structural parameters of the engine that determine its reliability.The reliability of the car (individual reliability properties or technical readiness) is influenced by the following factors: operating modes, operating conditions, quality of spare parts, qualifications and experience of drivers, etc. These factors show the direction and degree of the influence on the car and its reliability (technical readiness). The paper examines the influence of each factor on the reliability of the car.Methods and materials. To determine the effect of the starting mode of an internal combustion engine on a change in the structural parameter during forecasting, it is necessary to develop a methodology for determining the effect of the starting modes of internal combustion engines on changes in the structural parameters of the engine that determine its reliability. This technique involves conducting a full-factor experiment with four factors, i.e. 16 experiments. The combinations of different levels of factors are accepted as operational modes.To measure the magnitude of the influence of each factor on reliability, the article considers their measured values - indicators of the factor. There are from one to several indicators per factor. The values of the indicators are not constant, but change in accordance with changes in external influences (factors). Indicators are calculated based on the values of certain indicators of the direction of the influencing environment that a particular indicator describes.The total duration of the tests is assumed to be equal to the resource before major repairs.Results. The authors propose a method for determining the effect of starting modes of internal combustion engines on changes in the structural parameters of the engine that determine its reliability.The starting modes of the internal combustion engine and the dependence of reliability properties on external factors affecting the car at the time of engine start are considered. It is established that the degree of influence of factors is measured by the values of their indicators.Conclusion. As a result of using the proposed methodology for determining the effect of starting modes of internal combustion engines on changes in the structural parameters of the engine that determine its reliability, the principal possibility of an integrated approach to determine the effect on the structural parameters that determine reliability in the course of one series of experiments of both the influence of operating modes and engine starts, as well as the possibility of determining the influence and extreme values of factors is shown for reliability.Thus, the calculation of the values of one or another indicator enables to obtain the final values of the components of reliability (technical readiness). Indicators enables to determine the variability of factors affecting the components of reliability (technical readiness).

Product Quality Optimization by Applying the Six Sigma Methodology: DMAIC in CV XYZ (A Case Study of an Indonesian Subcontractor Company)

Reflecting the increasing demand in the motorcycle industry, it requires brands to sustain their product quality to meet customer satisfaction. The quality of the end product depends on the quality of spare parts. Hence, local suppliers were critical in ensuring the product quality is fulfilled. This research is limited only to CV XYZ which is known as a motorcycle spare part third-party supplier that is based in Cimahi, Indonesia. Recently, they faced decreasing customer trust because they obtained a “D” score in Performance Quality written in the Performance Supplier Report January 2023 that is sent by one of their customers. This research aims to identify solutions for the improvement of product quality. The Six Sigma Methodology DMAIC is the basis of this problem-solving research. The author utilizes historical data and undertakes the recommendation given by the previous study in literature reviews. The analysis proved that the process needs repair according to Performance Supplier Report. Three root causes of the issue with the shaper tools were overused, hasty working behavior, and lack of a monitoring system. Currently, these root causes were improperly handled. So, solutions proposed include reconditioning and scheduling, job rotation procedures, and the Poka-Yoke: Cleaning Numerator.

Analysis of the quality of manufacturing holes for sprockets of chain drives of agricultural machinery

The article has devoted to solving an urgent problem related to the analysis of the quality of manufacturing sprockets for chain drives of agricultural machinery. For the conditions of a technical service enterprise specializing in the maintenance and repair of agricultural machines, an experimental assessment and analysis of the quality of spare parts - sprockets, which have a fit on the shaft of the H090 gearbox of the Mosselmash plant. It had revealed that the factory set the requirements for the inner diameter of the sprocket Ø30H7(+0.021). Measurements of the hole of 100 stars had carried out, as a result of the analysis of the experimental data obtained, the following had established: scattering parameters and quality parameters for manufacturing controlled dimensions. Using empirical data, a histogram and a theoretical curve for the distribution of the internal diameters of the sprocket had constructed. It had revealed that the probability of the appearance of suitable parts is 83%, parts with a correctable defect − 8%, with an unrecoverable one − 9%. On the basis of the obtained data, in order to improve the quality of manufacturing chain sprockets, appropriate recommendations had made to the manufacturer.

Research on the Comparison between the Different Policies by Service Level and Inventory Level Performance of Auto Parts in N.A.C.C. (North Automobile Components Company)

As after sales services become more and more popular, particularly preventive or corrective maintenance, the intervention and repair of the customer’s goods in a timely and efficient manner ensure customer satisfaction and contribute to the establishment of brand image in the market of the suppliers. The availability and quality of spare parts are key elements of this strategy while ensuring minimal management costs. The reuse of spare parts retrieved from customer systems is a growing maintenance strategy practice which impacts the traditional spare parts supply chain. This reuse is primarily driven by extending the economic life of goods, initially regarded as waste and therefore without added value, by transforming them into valuable spare parts that can be reused; secondly, for environmental or regulatory reasons, demanding responsibility for the treatment of products at the end of their life; and thirdly, to improve the availability of parts for maintenance, especially parts that the organization can no longer purchase or that are impacted by other issues. It also involves the analysis of their condition and their eventual return to working order as they are retrieved from the customer’s systems in a defective condition. In this paper, we will identify and classify the different customers and spare parts by estimating the critical level of rationing policy based on forecasts, identify the thresholds of inventory management policies, and finally, compare the different policies by service level and inventory level performance for the N.A.C.C. company.

Analisis Aktivitas Bongkar Muat Kapal Untuk Eliminasi Pemborosan di PT. Pelayaran Timur Asri Laut

PT. Pelayaran Timur Asri Laut is the loading and unloading service company of various types of commodities. In the service process, operational performance is considered not optimal or there is waste which indirectly has an impact on the longer the berthing time of the ship, causing port congestion. The implementation of this study involves various activities such as identifying waste, analyzing the causes of waste occurring using the Lean Six Sigma method. The purpose is to analyze ship loading and unloading by identifying waste, analyzing the causes of waste and the factors causing demurrage in PT. Sea East Voyage. The results showed that the factors causing the highest waste category demurrage occurred in the Internal Equipment Breakdown, then using a fishbone diagram and FMEA for the factors causing of the problem to get the highest RPN value. The 5 highest causes of the RPN value are the Operator not in accordance with the SOP, short lifetime, monitoring has not been measured in real terms, the quality of spare parts is not good and the procurement of spare parts is not coordinated.

Developing a supplier selection model based on Markov chain and probability tree for a k-out-of-N system with different quality of spare parts

Spare parts management is one of the most important aspects in industrial systems where a large number of spare parts are stocked to replace with failed parts and reduce the system's downtime. In this study, it is supposed that the quality of spare parts can differ from the quality of the original parts since they might be supplied from different suppliers. This problem is modeled by using the probability tree and Markov chains approach to determine the optimal number of spare parts, their supplier, and appropriate quality, leading to minimization of the system's total cost and or system's total availability. Meanwhile, highly expensive parts cause large investment. In this study, a k-out-of-N redundant system is modeled in which by failing each part it is replaced by a stocked spare part if exists. Otherwise, in case of spare parts lacking the system continues to its operation with failed part(s) which reduces system performance. If the number of failed parts reaches a predetermined threshold level (N-k+1) it leads to system shutdown. All suggesting models are applied on numerical samples for to show the representation of the state and determine optimal spare parts supply strategies and inventory policies in large-scale industrial systems.

Analysis of the Aggregate Heuristic Planning for Planning and Controlling the Amount of Production to Minimize Costs

PT.XYZ is one of the companies engaged in the automotive manufacturing industy, where it produces spare parts for cars, motorcycles and trucks. Along with marketing and producing the products, PT.XYZ continues to implement customer satisfaction and the quality of spare parts produced. The company must anticipate the possibility of production capacity limitations; this must be done as well as possible at the minimum cost. For that, the aggregate heuristic planning is proposed for planning the establishment of a level for production capacity to meet the level of demand obtained from orders with the aim of minimizing total production costs. Aggregate Planning is a process of determining the level of overall production capacity to meet the level of demand obtained from forecasting and order with the aim of minimizing the total cost of production. In this study, three heuristic methods were tried, namely labor control method, subcontracting mixed method, and overtime mixed methods. Based on the results of the study it is known that the subcontracting mixed method is the best method with total aggregate cost of IDR 3,080,689,770, then the labor control method with a total of aggregate cost of IDR 3,080,798,198 and the overtime mixed method, with a total aggregate cost of IDR 3,081,815,315.

Preventive remanufacturing planning of production equipment under operational and imperfect maintenance constraints: A hybrid genetic algorithm based approach

Remanufacturing an equipment before the end of its life may generate substantial profits for both the user and the remanufacturer. However, the equipment operating conditions as well as the quality of maintenance actions undergone throughout the life of equipment largely affect the total life cycle costs from the user’s perspective, and the quality of the recovered equipment from the remanufacturer’s perspective. This research aims at investigating the remanufacturing opportunities of production equipment from the user’s perspective, used to produce a single product in order to meet deterministic and dynamic demands over a finite horizon. Preventive maintenance actions on equipment are assumed to be imperfect. Indeed, when performed, these actions can improve the equipment to reach a state between the “As-good-as-new” level and the “As-bad-as-old” level. It is assumed that the stakeholders (the equipment’s user and the original equipment manufacturer-remanufacturer) are interested by all remanufacturing opportunities. The objective of the present work is to develop an integrated approach to jointly optimize the production plan, the remanufacturing plan and the quality of spare parts used in each remanufacturing action.In order to minimize the total cost during the production horizon, a mixed-integer nonlinear program is developed. The optimization problem is solved using a hybrid genetic algorithm based on a fix-and-relax heuristic. A numerical experiment and a sensitivity analysis are presented to illustrate the applicability of the proposed approach.

Enhancing building maintenance cost performance with proper management of spare parts

Purpose – Scheduled building maintenance requires appropriate and adequate spare parts to replace existing parts on a regular basis. Management of spare parts is seen as an important criterion to ensure the efficiency of scheduled maintenance. The purpose of this paper is to identify the contributors of spare parts management and investigate the relationship between these contributors and maintenance cost performance. Design/methodology/approach – This research adopted a quantitative approach, which utilised questionnaire surveys to study the relationship between the contributors of spare parts management and maintenance cost performance. The data were analysed through descriptive analysis, correlation, and regression analysis. Additionally, a case study was examined to validate the results obtained from the survey. Findings – The results of this research demonstrated that the quality of spare parts (QSP), budget allocation for acquisition of spare parts, and level of stocks were significantly correlated to the maintenance cost variance (MCV). Moreover, the results of the regression analysis indicated that the QSP was the significant predictor of MCV. Originality/value – This research highlights the importance of spare parts management in building maintenance. It recommends that maintenance management set up a spare parts management department for updating stocks frequently. Meanwhile, the management should avoid ad-hoc acquisition of spare parts, as this is always more expensive. The management should also select spare parts based on quality instead of lowest cost. In addition, building managers should also apply the developed regression model in practice to predict and improve maintenance performance.

Improving occupants' satisfaction with effective maintenance management of HVAC system in office buildings

Office buildings are equipped with HVAC system to provide a comfortable working environment. However, the level of the occupants' productivity and comfort is highly influenced by the reliability of HVAC system's service. Thus, the proper maintenance of HVAC system is necessary to ensure the smooth operations of an organisation. This paper seeks to investigate the maintenance characteristics of HVAC system that affect occupants' satisfaction and subsequently establish a relationship between the characteristics and occupants' satisfaction through questionnaire surveys and interviews; and finally develop a regression model for prediction purpose. The findings reveal that the maintenance characteristics which influence occupants' satisfaction include the skill and knowledge of the manager, the skill and knowledge of the labourer, the quality of spare parts and materials, as well as the response level towards failure and downtime. The study concludes that an effective communication platform which involves all key participants in the maintenance activities should be developed by the management to improve the maintenance outcomes.

Preventive Maintenance Characteristics towards Optimal Maintenance Performance: A Case Study of Office Buildings

Lack of preventive measure is currently the problem that implicates poor building maintenance performance and issue on sustainability of buildings in Malaysia. Whereby, preventive maintenance is an effective approach to enhance the reliability and quality of a system and its components. This study seeks to investigate the characteristics of preventive maintenance towards the overall performance in building maintenance. Case study approach is adopted to identify the maintenance characteristics and aspects that lead to good performance. The research findings demonstrate that the most significant maintenance characteristics towards overall performance are skill and knowledge of maintenance labour, quality of spare parts and materials, length of predetermined maintenance interval, skill and knowledge of maintenance manager, capability to adopt maintenance equipment and technique, budget allocation for acquisition of maintenance data, reliability of maintenance data, as well as frequency of monitoring and inspection. As a conclusion, the significant maintenance characteristics must be taken into consideration to achieve optimal maintenance performance. In order to improve the effectiveness of maintenance strategy and the maintenance performance, the study recommends practice and provision of communication platform such as meeting and customer satisfaction survey that involves all the key participants from clients to customers.

The Effect of Maintenance Quality on Spare Parts Inventory for a Fleet of Assets

This paper considers the effect of fleet size on a joint policy of maintenance and spare parts inventory when spare parts are of varying quality. We consider N identical one-component systems subject to age-based replacement, and with a single echelon periodic review spare-parts policy. The joint policy is optimised with regard to the long-run total cost per unit time, where the cost components include both replacement and inventory related costs. In particular, we are interested in the effect of spare parts quality and the size of the fleet on the variability in the demand for spare parts. Furthermore, the effects of changing lead time, different failure characteristics, and simultaneous deployment of the N systems over a finite horizon on the optimal joint policy are investigated. We develop a stochastic simulation model to investigate these effects. We find that the scale effect varies with the quality of spare parts: the poorer the quality of spare parts, the smaller the scale effect. Our approach allows the value (e.g. cost of poor quality spare parts) in spare parts provisioning for maintenance to be quantified.

Status of Farm Mechanization in Ilocos Sur

This study sought to determine the status offarm mechanization in Ilocos Sur, specifically the socio-economic profile of the farmerrespondents, their mechanization patterns, their perception of the importance of farm mechanization, and their problems in the use of farm machines. The respondents of this study were 946 farmers from 34 municipalities of Ilocos Sur. A questionnaire checklist was used in data gathering. Frequencies, percentages, and weightedmeanswere used in data analysis. Majority of the farmer-respondents were male, middle-aged, finished high school, and had a monthly income below the poverty threshold level. They used farm machines in crop production, harvesting, and postharvest activities. The most common farm machines they used were kuliglig, four-wheeled tractors, water pumps, power sprayers, power thresher, tractor/jeep with trailer, and rice mill. They perceived that farm mechanization had much importance in all their farming activities. Although they accepted the use of machines infarming, they were doubtful whether or not they could buy their own farm machines because they were very expensive. The farmer-respondents had problems in maintaining their farm machines, high cost of spareparts and fuel, limited supply and low quality of spare parts, and difficulty in operating the machines. Government support particularly in purchasing and operating farm machines to be rented by the farmers was thefore most suggestion to solve these problems.

Nabavka i ocena kvaliteta rezervnih delova za potrebe Vojske Jugoslavije

Nabavka i ocena kvaliteta rezervnih delova za potrebe Vojske Jugoslavije

Improving the quality of spare parts, an important condition for increasing production effectiveness

Improving the quality of spare parts, an important condition for increasing production effectiveness