Stemming plugs are one of the widely used accessory in surface mining operations. Stemming plugs assist conventional stemming material in gas retention and help in better fragmentation and explosive utilization. Effective use of the stemming plugs results in economic benefits and enhance the efficacy of the project. Economic and productive viability of stemming plugs have been conducted in depth by different researchers. Addition of stemming plugs to a new system requires ergonomic challenges for operators conducting drilling and blasting operation. Induction of a newer product in already established system is subject to overall positive feedback. This work investigates ergonomics of three different stemming plugs introduced to a limestone quarry in Pakistan. The stemming plugs were evaluated based on extra time needed, workers feedback, failures during operation, recovery time after failure and number of extra equipment required to carry out the operation. Points based matrix was established with likeliness of each plug and based on overall scores stemming plug 1 was most acceptable followed by stemming plug 3. Stemming plug 2 was disliked by operation and did not reach the level of acceptability of operators. This work will help stemming plug making industry in adapting to best practices by incorporating ergonomics of plugs in designing. Literature shows no previous work on ergonomics of stemming plugs.
The scope of this work focuses on the aspects of quality and safety assurance of the iron cast manufacturing processes. Special attention
was given to the processes of quality control and after-machining of iron casts manufactured on automatic foundry lines. Due to low level
of automation and huge work intensity at this stage of the process, a model area was established which underwent reorganization
in accordance with the assumptions of the World Class Manufacturing (WCM). An analysis of work intensity was carried out and the costs
were divided in order to identify operations with no value added, particularly at individual manufacturing departments. Also an analysis
of ergonomics at work stations was carried out to eliminate activities that are uncomfortable and dangerous to the workers' health. Several
solutions were proposed in terms of rationalization of work organization at iron cast after-machining work stations. The proposed solutions
were assessed with the use of multi-criteria assessment tools and then the best variant was selected based on the assumed optimization
criteria. The summary of the obtained results reflects benefits from implementation of the proposed solutions.
The article presents the issues of costs analysis of iron casts manufacturing using automated foundry lines. Particular attention was paid to departmental costs, conversion costs and costs of in-plant transport. After the Pareto analysis had been carried out, it was possible to set the model area of the process and focus on improving activities related to finishing of a chosen group of casts. In order to eliminate losses, the activities realised in this domain were divided into activities with added value, activities with partially added value and activities without added value. To streamline the production flow, it was proposed to change the location of workstations related to grinding, control and machining of casts. Within the process of constant improvement of manufacturing processes, the aspect of work ergonomics at a workstation was taken into account. As a result of the undertaken actions, some activities without added value were eliminated, efficiency was increased and prime costs of manufacturing casts with regard to finishing treatment were lowered.
The paper presents a practical example of improving quality and occupational safety on automated casting lines. Working conditions
on the line of box moulding with horizontal mould split were analysed due to low degree of automation at the stage of cores or filters
installation as well as spheroidizing mortar dosing. A simulation analysis was carried out, which was related to the grounds of introducing
an automatic mortar dispenser to the mould. To carry out the research, a simulation model of a line in universal Arena software
for modelling and simulation of manufacturing systems by Rockwell Software Inc. was created. A simulation experiment was carried out
on a model in order to determine basic parameters of the working system. Organization and working conditions in other sections of the line
were also analysed, paying particular attention to quality, ergonomics and occupational safety. Ergonomics analysis was carried out
on manual cores installation workplace and filters installation workplace, and changes to these workplaces were suggested in order
to eliminate actions being unnecessary and onerous for employees.
The paper presents a practical example of improvement of foundry production systems in terms of post-finishing of nodular iron castings
produced in the conditions of bulk production for automotive industry. The attention was paid to high labour-intensive efforts, which
are difficult to be subjected to mechanization and automation. The times of actions related to grinding processing of castings in three
grinding positions connected with a belt conveyor were estimated with the use of a time study method. A bottleneck as well as limiting
factors were specified in a system. A number of improvements were proposed, aimed at improving work organization on the castings postfinishing
line. An analysis of work ergonomics at the workplace was made in order to eliminate unnecessary and onerous for the employee
actions. A model of production system using the Arena software, on which a simulation experiment was conducted, was drawn up in order
to visualize the analysed phenomena. The effects of the project were shown on graphs comparing times, costs, work ergonomics and
overall efficiency of production equipment indicator.
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