The planing and moulding sector of the timber industry is a complexmachining environment. The production process is hampered by short toollife, frequent job changes and long…
Abstract
The planing and moulding sector of the timber industry is a complex machining environment. The production process is hampered by short tool life, frequent job changes and long set‐up times with a concomitant machine utilization of as little as 30 per cent. Investigates the requirements for finished timber section production and develops a strategy for alleviating the most significant production bottlenecks to reduce downtime. The proposed scheme offers a considerable reduction in downtime via the efficient control and passage of machining data and embodiments of machine setting aids. This provides a platform for successful CIM implementation.
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J. Brettle and S. Orman
Introduction The ever increasing demands made on materials by advanced technology has led, in recent years, to a greater awareness of the importance of mechano‐chemical behaviour…
Abstract
Introduction The ever increasing demands made on materials by advanced technology has led, in recent years, to a greater awareness of the importance of mechano‐chemical behaviour. These may be defined as the synergistic effect of mechanical forces and chemical reactions on the material. Although possibly interrelated, three classes of mechano‐chemical reactions have been identified as; stress‐corrosion (SCC), corrosion fatigue (CF) and hydrogen embrittlement. SCC has become one of the ‘in’ subjects of corrosion science during the last decade, while the importance of CF has emerged comparatively recently. In a review of the national corrosion and protection scene in 1970, it was revealed that 62 postgraduate research workers, representing 21% of the total effort in the corrosion and protection field, were involved in mechano‐chemical corrosion studies1. The bulk of these were working on SCC. This large research effort has not resulted in a standardisation of test methods nor, despite several attempts, in a unifying theory for SCC2. The newcomer to the field is faced with a bewildering variety of tests of varying complexity and validity. The supporters of each type of test tend to make exaggerated claims particularly when the test they are advocating is the only one which has caused a particular alloy‐environment system to exhibit SCC.
Although the wind of change is blowing strongly through the gas industry a substantial proportion of the gas, for some time to come, will be made by coal carbonisation and by…
Abstract
Although the wind of change is blowing strongly through the gas industry a substantial proportion of the gas, for some time to come, will be made by coal carbonisation and by carburetting water gas. Even these more conventional methods will be subject to change such as the choice of lower‐rank coals to produce reactive smokeless solid fuels and the use of light Hydrocarbon oils, such as primary flash distillate, in place of gas oil. This article deals with some of the corrosion problems that arise in these more established types of plant.
Chukwudi C. Olumba, Cynthia N. Olumba and Chukwuma Ume
Taking a gender-sensitive approach, this study examines the socio-economic and institutional drivers of household vulnerability to the shocks occasioned by the COVID-19 pandemic…
Abstract
Taking a gender-sensitive approach, this study examines the socio-economic and institutional drivers of household vulnerability to the shocks occasioned by the COVID-19 pandemic. The study employs country-level panel data for Nigeria. Data collected were analysed using descriptive statistics, Pearson's chi-square, and ordered logistic regression. The study found significant heterogeneity in vulnerability to the COVID-19 shocks between the male-headed households (MHHs) and female-headed households (FHHs) (p < 0.1). The econometric results reveal that in the MHHs, the geographical location, livelihood diversification, and ownership of television were the significant drivers of vulnerability to COVID-19–related shocks. In the FHHs, credit constraints, household size, value of the household assets, geographical location, ownership of television and radio, and experiences of previous shocks were found to be significant drivers of vulnerability to COVID-19–related shocks. This study provides insights for designing inclusive social protection interventions and gender-sensitive COVID-19 recovery policies.
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Certain classes of organic chemicals that can behave like carbon black in protecting polythene from thermal degredation have recently been developed at Bell Telephone laboratories…
Abstract
Certain classes of organic chemicals that can behave like carbon black in protecting polythene from thermal degredation have recently been developed at Bell Telephone laboratories in the U.S.A. Mrs. A. Worthington and Dr. W. L. Hawkins described their discovery at a recent meeting of the American Chemical Society in New York. They demonstrated that a number of compounds containing alternating unsaturated bonds provide excellent thermal anti‐oxidant properties in combination with previously reported sulphur‐bearing compounds.
Mustafa Graisa and Amin Al‐Habaibeh
The purpose of this paper is to investigate maintenance and production problems in the cement industry in Libya, with particular emphasis on future implementation of total…
Abstract
Purpose
The purpose of this paper is to investigate maintenance and production problems in the cement industry in Libya, with particular emphasis on future implementation of total productive maintenance (TPM).
Design/methodology/approach
The paper presents the use of case study approach of production data and history, field visits, a survey methodology using a detailed questionnaire with employees and interviews with top and middle managers in four cement factories.
Findings
It has been found that the four factories under investigation have low productivity and production levels when compared with the design values. There is no clear TPM strategy and also it has been found that the lack of training and personal development is the main cause of this problem. In addition, employees are found not to be motivated as a result of the lack of a management strategy and reward structure.
Research limitations/implications
Based on the findings, a new framework for TPM has been developed. This TPM strategy could be implemented in other Libyan factories as a result of the potential similarities in the cultural and environmental aspects.
Practical implications
The current challenges have been identified and comparative analysis is developed into a model for the implementation of TPM.
Originality/value
The paper highlights limitations in some of the cement factories in Libya in relation to TPM and production strategies. The importance of adopting a realistic strategy and framework by managers is discussed. This work is developed as collaboration between academia and one of the Libyan cement companies to solve productivity problems and develop a strategic framework of TPM for improving Libyan industry.
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Girish Hariharan and Raghuvir Pai
This study aims to investigate the performance characteristics of an externally adjustable bearing with multiple pads in steady state conditions. The proposed adjustable bearing…
Abstract
Purpose
This study aims to investigate the performance characteristics of an externally adjustable bearing with multiple pads in steady state conditions. The proposed adjustable bearing geometry can effectively control the hydrodynamic operation in bearing clearances by adjusting the pads in radial and tilt directions. These pad adjustments have a significant role in improving the bearing characteristics such as load capacity, attitude angle, side leakage, friction variable and Sommerfeld number, which will be analysed in this paper.
Design/methodology/approach
The adjustable bearing is designed with circumferentially spaced four bearing pads subjected to similar radial and tilt adjustments. Tilt angles are applied along the leading edges of bearing pads. A modified film thickness equation is used to incorporate the pad adjustments and accurately predict the variation in film profile. Finite difference approximation is adopted to solve the Reynolds equation and discretize the fluid film domain.
Findings
For negative radial and tilt adjustments, higher hydrodynamic pressures are generated in bearing clearances, which increases the bearing load capacity at different eccentricity ratios. From comparative analysis for different pad adjustments, superior bearing performance is observed for bearing pads under negative radial and negative tilt adjustments.
Originality/value
This research presents a detailed theoretical approach to analyse the performance capability of a four pad adjustable bearing geometry, which is not available in literatures. Improved bearing performances with negative pad adjustments can attract bearing designers to implement the proposed adjustability-bearing concept in rotating machineries.
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Last month Dr. Parkins described the various types of pitting corrosion which may appear in steam boilers. In Part 2 corrosion associated with high concentrations of caustic soda…
Abstract
Last month Dr. Parkins described the various types of pitting corrosion which may appear in steam boilers. In Part 2 corrosion associated with high concentrations of caustic soda (caustic cracking), corrosion fatigue and the deterioration due to local overheating are discussed.