Tahir Ayar

Maintenance in Manufacturing Environment: An Overview

Maintenance is one of the major activities in manufacturing as it highly influences production quality and quantity and directly affects production cost and customer satisfaction. As new manufacturing technologies emerge and global communication advances, new maintenance practices are developed to cope with these changes. The role of maintenance in maintaining asset value over time is getting more visible at the business level with the increase in its acquisition and maintenance costs. In this chapter, various manufacturing systems are introduced along with their distinctive features that influence maintenance strategies and practices. Maintenances management concepts, philosophies, policies, and practices in manufacturing are briefly described and discussed in this chapter.

Laser welding: the first and second law analysis

Thermal efficiency analysis can be used to minimise the energy losses in laser welding. In the present study, laser welding and efficiency analysis are considered. The first and second law efficiencies for the welding process are formulated and quantified for new parameters associated with the welding geometry. These parameters include excess mass ratio, loss mass ratio, and heat loss ratio. It is found that the first and second law efficiencies improve gradually with increasing excess mass ratio. However, the first and second law efficiencies reduce with increasing loss mass ratio and heat loss ratio, provided the decrease in efficiencies with increasing heat loss ratio is gradual.

Efficiency analysis of laser hole cutting

The efficiency analysis of laser cutting of holes into Kevlar plates is carried out and the specific energy requirement for cutting is computed for different cutting speeds and laser output power levels. The maximum laser scanning speed required for cutting Kevlar plates of different thicknesses is determined. It is found that the minimum specific energy requirements decrease with increasing hole diameter. The energy and exergy efficiencies predicted are related to the resulting cut quality and it is concluded that cutting quality improves significantly at high energy and exergy efficiencies.

Integrated Maintenance Planning

Maintenance planning and scheduling require utilization of resources at a maximum level. Integrated maintenance planning is an approach in planning that takes into consideration global production systems at the business level. It considers the expectation of all internal and external stakeholders of the maintenance function to secure the maximum benefits from the whole system. In this chapter, the process of high level (strategic) planning that links maintenance strategies to business and production strategies is described. The traditional low level (operational) planning and scheduling linked with the strategic level plan is also described.

Thermodynamic Optimization of Irreversible Radiation-Driven Power Plants

AbstractA second-law thermodynamic analysis is carried out for a solar-driven power plant subjected to radiation and convection heat transfer. The collective role of radiation and convection modes of heat transfer is investigated. Heat transfer from a hot reservoir is assumed to be radiation dominated, whereas convection heat transfer is assumed to be the primary mode of heat transfer to a low temperature reservoir. The irreversibilities resulting from these finite rates of heat transfer are considered in determining the limits of efficiency and power generation that are discussed through varying process parameters. The upper limit is found to be a function of both the functional temperature dependence and of heat transfer and relevant system parameters.

Laser Cutting of Ceramic and Thermal Efficiency Analysis

Laser cutting of ceramics offers considerable advantages over the conventional cutting methods. Some of these advantages include precision of operation, high speed processing and low cost. In addition, cutting process is independent of the mechanical properties of the ceramic material such as hardness and fracture toughness. Alumina is one of the widely used ceramics in industry due to their resistance to harsh environments. Laser cutting of alumina requires high laser power due to high latent heat of melting and elevated melting temperature. In efficient laser cutting process, the low laser power is required. Consequently, for optimum laser cutting conditions of alumina tiles, the thermal efficiency of the cutting process may not be a maximum. The optimum laser cutting parameters provide crack free and parallel edge cuts. Therefore, investigation into laser cutting of alumina ties and the efficiency analysis becomes essential. In the present study, laser cutting of alumina tiles with 3 mm thickness is carried out and thermodynamic analysis associated with the efficiency analysis is introduced. The lump parameter method is incorporated in the thermodynamic analysis. The optimum cutting conditions are then related to the first and second law efficiencies.

9.11 – Laser Cutting Efficiency and Quality Assessments

Thermal analysis of laser cutting process is carried out and the first and the second law efficiencies of the cutting process are formulated. Thermal efficiencies are predicted for various laser scanning speeds and laser output power levels. The experiment is conducted to examine the resulting cutting sections. The F-test is conducted to assess the end product (cutting section) quality and, later, the thermal efficiencies are related to the end product quality. It is found that increasing laser output power lowers the first and the second law efficiencies of cutting, which is more pronounced with reducing the laser scanning speeds. The end product quality improves for low laser output power levels and high laser scanning speeds as similar to the thermal efficiencies.

Laser Drilling and Efficiency Analysis

In this chapter, the first and the second law efficiency analyses of laser cutting of holes are carried out and specific energy requirement for cutting is computed for different cutting speeds and laser output power levels. Maximum laser scanning speed required for hole cutting of different workpiece thickness is determined. It is shown that the minimum specific energy requirements decrease with increasing hole diameter. It is also shown that the exergy efficiency is lower than the energy efficiency. The energy and exergy efficiencies predicted are related to the resulting cut quality. As an experimental case study, Kevlar plates are considered and it is shown that cutting quality improves significantly at high energy and exergy efficiencies.

Health, Safety and Sustainability in Maintenance

Maintenance is one of the key issues for retaining values of assets and achieving the desired performance. However, maintenance is also a major element in providing and maintaining a safe and healthy working environment for the people within the manufacturing facility and in its neighborhood. Ill-maintained asset, machinery, or structure is a potential source of serious health problems and accidents. In this chapter, health and safety issues related to the maintenance itself and to its impact on the work environment are presented in the manufacturing setting.

Recent and Future Trends in Maintenance

Maintenance is globally important to sustain equipment, process, and measures. It has also multidisciplinary features combining almost all engineering fields, mathematics, statistics, information sciences, and management. In this chapter, recent developments and future trends in maintenance in relation to all the above fields are briefly presented.