Applied Mechanics and Materials Vols. 809-810

Abstract: In this paper, problem of sequencing of production orders in mixed-model assembly systems is being analysed. The sequencing in such system is mostly addressed as a CSP problem (Car Sequencing Problem) and due to the fact that no optimal method of solution has yet been found it belongs to the NP-hard problems [1,2]. The NP-hardness of the problem has been proven in [3]. The problem connected with proper sequencing arises from the fact that nowadays it’s the clients who have the biggest influence on the sellers offer. The possibility to customize almost each and every product complicates the production management, as instead of having 10 different products, the number of them may grow up to few hundreds [4]. The problem may be especially observed in automotive industry, however recently it may be also met in household appliances industry, as mass customization can be also observed on that market. Each product may differ in labor-effectiveness, and due to the fact of carrying the assembly in linear assembly systems, each unevenness, each transgression of takt time on a single work-station may lead to the line stoppage.

Abstract: The ring frame is the last machine in the technological process to obtain a high quality yarn. The existing machines in textile industry of our country are equipped with drafting assembly suitable for a series of adjustments. Besides this, the ring frames ensure high draft. The efficiency of this high drafts can be justified through their influence on ring frame production. Another technologic parameter that is related on one hand to the yarn quality and on the other hand to the production is the spindles speed. In this paper it is presented a solution for spinning process optimisation for a yarn Nm 52 made by 45% wool and 55% polyester.

Abstract: Maintenance service is the necessary organizational structure in the modern manufacturing company. Everyday maintenance services operation would be greatly impeded without a computerised maintenance management systems (CMMS) software. CMMS allows to manage company’s equipment, planning inspections and maintenance and management supervision procedures and service documentation. The aim of this study is to present the analysis of the manufacturing company in the maintenance department, the main objectives of the company related to the maintenance, a pre-implementation analysis (objectives, assumptions, hard results, ABC analysis), and proposals to choose computerised maintenance management systems, which will allow to reduce failures, downtime and maintenance costs.

Abstract: A single reliable-machine manufacturing line with finite buffer capacity is considered, in which each idle period is preceded by a random closedown time, and each busy period is preceded by a random setup time. The stream of arriving jobs is described by a simple Poisson process, while processing (service), closedown and setup times are generally distributed random variables. A system of Volterra-type integral equations for the transient queue-size distribution conditioned by the initial level of buffer saturation is found by using the Markov property of successive service completion epochs and the continuous version of total probability law. A parallel system written for Laplace transforms is obtained and written in a specific form. The solution of the latter system is derived in a compact-form applying the linear algebraic approach. The final representations are found in terms of “input” system parameters (transforms of processing, closedown and setup times’ distributions) and certain sequence defined recursively.

Abstract: Warehousing enables the consolidation of shipments to clients by assembling full truck loads from goods stored in warehouse or distribution center. Storage can be efficiently replenished by ordering full truck loads from suppliers. In order to reduce freight storage and handling costs from distribution centers, cross-docking technique represents a logistic solution which is more and more used. Thus, the optimization of simultaneous unloading/loading operations constitutes an important issue for the distribution center owner/administrator. This paper presents a model based on genetic algorithms optimization techniques for solving the problem of unloading/loading ramps allocation. The efficiency of a cross-docking center is conditioned practically by finding an allocation and an optimal arrangement of ramps. This implies the allocation of destinations to unloading/loading ramps of distribution centers to minimize the total distance performed by the the cargo handling equipment. The case study presents a cross-docking platform with single handling equipment which is assigned to 10 unloading/loading ramps. By applying the solution of the ramp allocation generated through simulation, the total distance performed by the handling equipment is reduced which means lower handling cost for the distribution center owner/administrator.

Abstract: Nowadays, sustainability is the new trend in product design and treats the environmental issues in a more spherical manner. This is achieved by considering the whole lifecycle of the product in advance. When design is implemented, this approach becomes the conceptual base for developing a great deal of products and services. Many ‘design for X’ methodologies have been developed, refined, and now they are commonly used. The current paper reviews a series of available design methodologies. It classifies them based on the life cycle stage that they are implemented. The vast majority of them have a strong focus on manufacturing issues. Even when they focus on the product-use phase, they are dominated by the manufacturer’s decisions. The users’ interaction with a product may strongly influence its environmental impact, and for this reason designers should put extra effort in order to influence this behavior. Based on this demand there is a necessity for the development of novel methodologies and tools, which would be directly related to the use phase of the products. In recent years, a design methodology called User-Centered Design (UCD) is under consideration with an aim to understand the users’ needs, goals, limitations, possibilities, previous experiences and how they are affecting the user interaction with objects. The present paper proposes a new methodology named Design for Green Usability (DfGU), which is directly linked to the user requirements during the use phase of the product.

Abstract: Companies must respond quickly to customer needs and ensure the desired quality and low price in order to remain competitive in a market. It becomes necessary to create new concepts of production systems that meet all requirements imposed by consumers. The increase of reliability of machines and equipment, staff competence and forecasting a size and subject of demand increase the ability to react quickly to changes in the business environment. Therefore, the objective of this paper is to estimate the agility characteristics of a company (size of demand, interarrival time of orders and reliability of machines) and to verify its production capacity and rapid response capabilities. The characteristics are estimated for three variants of the production system: self-operating company, companies operating in cooperation, company buying additional machine.

Abstract: The article is dealing with two problems regards the quality management in automotive industry such as: human resources management and processes monitoring. This connection is really difficult because of entrepreneurs generally have a problem with processes monitoring. Additionally human resources management is unmeasurable, so measurement must often be done using qualitative criteria, rather than quantitative. Furthermore the regulations of the new ISO 9001 include evaluate the performance of processes. It emphasizes the importance of the problem. The study provides examples of ways to monitor the process of human resource management in small and medium-sized enterprises automotive. Examples were evaluated for suitability to assess the effectiveness of the process and to generate guidelines for improvement. The form of keeping and visualization in order to use the information for periodic reviews of the management was discussed.

Abstract: Critical Chain Project Management (CCPM) is based on a network planning and the Theory of Constraints. The importance of management of uncertainty and deviations that occur during a project is emphasized. The probability of the project completion in a predefined time limit, or even before the time limit is increased. Literature analysis indicates that other types of buffers must be applied (buffer supporting a project, buffer reacting on a critical path, buffer reacting on a non-critical path) apart of feeding, resource and project buffers. Applying the additional buffers keeps the critical path in the same position and maintains the unchanging due date of the project. Methods estimating size of feeding and project buffers are identified: half of the chain method, square root of fault method, modified method of square root of fault, method taking into account due date of the project. In this paper, a new method estimating a size of resource buffer and selecting a location of resource buffer based on the theory of probability is presented. In this paper, the CCPM method is applied to estimate due date of the mining machine production project.

Abstract: The article addresses the issue of using innovative high performance technology, integrated into a unitary concept for (re)manufacturing of various types of industrial products, respecting the concepts of circular economy. This article is focus on methods and applications of remanufacturing concepts at company and inter-company level, applied in the lifecycle management of industrial products, used as resources in circular economy.