International Refereed Journal of Engineering and Science (IRJES) ISSN (Online) 2319-183X, (Print) 2319-1821 Volume 2, Issue 6 (June 2013), PP.10-21 www.irjes.com
Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop A of the Company X Álvaro Manoel Santos Pinheiro1, Henrique Alves Muniz2, Guilherme Bernardes3, Raíssa Márcia de Souza Soares4 and Suélio da Silva Araújo5 1
Engineering student at the Faculty of Technology, University of Brasilia, Distrito Federal, Brazil. Engineering student at the Faculty of Technology, University of Brasilia, Distrito Federal, Brazil. 3 Engineering student at the Faculty of Technology, University of Brasilia, Distrito Federal, Brazil. 4 Engineering student at the Faculty of Technology, University of Brasilia, Distrito Federal, Brazil. 5 Masters Degree in Civil Engineering from the Federal University of Goiás, Brazil (2011), Civil Engineer, Technologist Planning and Building Construction and Master Research by the National Council of Scientific and Technological Development. Professor at the Faculty of Technology, University of Brasilia, Distrito Federal, Brazil. Rua A, Número 141, Bairro Mato Grosso, CEP: 76.200-000, Iporá, Goiás – Brasil. 2
ABSTRACT: - This paper presents an analysis from the point of view of Course Hygiene and Safety on the Activity of manufacture of parts through the aluminum smelter in the Workshop A of Company X. It also presents a brief case study about the accident at that workshop. Keyword: - Working; Manufacturing; Parts; Foundry; Workshop A; Company X.
I.
INTRODUCTION
1.1 CASTING WITH MOLD SAND The metal casting process is quite old, having its origins in the smelting of iron and copper already used in 3000 BC and developed significantly from the year 1340 with the invention of the oven streaming. To enable the manufacture of pieces with different geometries has developed a casting mold, wherein the mold with the shape of the part to be manufactured is filled with molten metal. The foundry sand mold allows the manufacture of parts with very complex geometries, but is an initial method of manufacture, and is usually followed by machining and heat treatments to achieve the desired result. The weaknesses of manufacturing by using foundry sand mold include high tolerances and embrittlement part due to the changes incurred in the grain structure of the metal by heating and phase change. The sand mold casting is used extensively in the steel industry for the manufacture of billets and rods. It is from them that all other geometries are manufactured marketed, such as pipes and plates. In automotive casting is of vital importance because it is the method currently used in the manufacture 100% of the blocks of combustion engines, these are aluminum or cast iron. Figure 1 shows a block motor Ford Mustang V6 3.7 L made of cast aluminum.
Figura 1 - Bloco de motor do Ford Mustang V6 3,7L fabricado em alumínio fundido
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop‌ 1.2 STEPS In sand mold casting are adopted the following basic steps for making a part: 1) Construction of the model: It is necessary to make a model of the part to be cast, which is usually done using wood, resin or foam, depending on the complexity of the form, available resources and the desired accuracy. Figure 2 shows an example of construction of a model to be fused.
Figure 2 - In sand mold casting are adopted the following basic steps for making a part 2) Construction of the mold: From model manufactured, is necessary to build the mold. Green sand is generally used at this stage because of their favorable properties, such as its high rigidity required for molding. There is a need to shake the sand in a pre-mixer to reach an acceptable grain size. For construction of the mold are used two boxes filled with steel molding green sand. The model is introduced in molding boxes and must fill the place formerly occupied by sand molding boxes. For obtaining a good mold is to compact the sand, removing the voids. After filling in both boxes are made in the mold runners for the passage of molten metal and the template is removed. Figure 3 shows examples of molds used in the Workshop A of the Company X.
Figure 3 - Examples of molds used in the Workshop A of the Company X 3) Casting: The metal chosen, in this case aluminum is melted in a gas oven. The solid aluminum pieces are introduced into a "crucible" which is taken to the furnace. The oven should be able to reach temperatures above 700 °C to carry out the casting of aluminum, whose melting point is around 660 °C. To facilitate the release of gases desgaiseficante a powder is added to the aluminum being cast. Figure 4 shows an example of a metal that will melt.
Figure 4 - Example of molten metal to be
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop‌ 4) Filling: After casting metal, it must be introduced into the mold for the effective part manufacturing. The crucible and molten aluminum is removed from the oven with the aid of a claw and is then poured into the sprue of the mold, filling it completely. Figure 5 shows an example of filling the mold with molten metal.
Figure 5 - Example of filling the mold with molten metal 5) Demoulding: After cooling the workpiece is held within its removal from the mold. The sand mold is destroyed, and the sand recycled and part is removed for its cleaning is performed with abrasive jets and subsequent work piece by machining in order to obtain adequate tolerances and finishing. 1.3 MATERIALS To carry out the work of casting need the following materials and tools: - Gas oven - Refractory crucibles - Green sand - Molding boxes - Mixing sand - Pestle - Sieve - Powder desgaseificante (lycopodium) - Claw - Aluminum To ensure the safety of the work requires the following personal protective equipment: - Glasses - Hoses - Gloves - Apron - Boots - Pants - Mask
II.
RISK ANALYSIS
2.1 METHODS OF RISK ANALYSIS The identification of the risks involved in work activities is of utmost importance. It is through the identification of risks that can develop a plan of risk control and eliminate hazards. There are several ways to identify risks, such as risk maps, checklists, safety inspections, accident investigations and flowcharts. From the identification of risk analysis is conducted of these, thus enabling its categorization according to probability of occurrence and severity of impact. To perform risk analysis have been developed several methods, the most notable being the Preliminary Risk Analysis (PRA), the Fault Tree Analysis (FTA) and the method HAZOP (Hazard Operability Analysis). This work will be addressed only the first two methods.
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop… 2.2 PRELIMINARY RISK ANALYSIS (PRA) The preliminary risk analysis is a method of initial analysis, involving a detailed analysis of all procedures covered by a given operation. It is usually performed in the design phase or development of a system and aims to determine the risks involved in each stage of the process and determine the preventive measures to be adopted. Looking closely at the process of manufacturing parts for casting sand mold was possible to identify all the processes involved in manufacturing and the risks involved in each. With the risks identified was constructed table preliminary risk analysis, which presents risks categorized by type, its causes, effects and preventive measures adopted category. A complete table of preliminary risk analysis is presented in APPENDIX I. 2.3 ANALYSIS OF FAULT TREE (AAF) The fault tree analysis was developed based on an accidentin in the Workshop A of the Company X. This accident incurred severe burns technician manipulating the apparatus as well as moderate burns in two and a third light. The activity performed involves considerable risks and considering that occurred during the execution of work involving about 12 people, the consequences were severe, but could have been more severe, such as loss of vision as a result of a burn on the eyeball. All activity was filmed by one of the people involved, which allowed the careful analysis of the accident, including serving as an example for the Department of Safety and Hygiene at Work for a great company in the field of aluminum. By analyzing the accident, rose two hypotheses for the accident. The first involves the lack of hygiene and inspection of equipment used. The ingot in which the leftover liquid aluminum was deposited had not been properly sanitized and contained solid particles from welding or other activity involving steel performed in the same physical environment. These particles reacted with molten aluminum at high temperature (between 700 ºC and 800 ºC), causing the violent expulsion of the liquid metal. Another hypothesis to be considered is the cooling sudden liquid aluminum when in contact with the ingot due to the high coefficient of heat transfer due to the temperature difference between the liquid aluminum (between 700 ºC and 800 ºC) and the ingot at room temperature (between 20 °C and 25 ºC) and also the material ingot high thermal conductivity (carbon steel). Another important point to be noted is the lack of use of Personal Protective Equipment (PPE) while performing the activity, which could have prevented the burns experienced by the technical workshop and also by people. The fault tree analysis is found in APPENDIX II.
III.
ERGONOMIC ANALYSIS
3.1 ERGONOMIC ANALYSIS Ergonomics at work is governed by a Regulatory Norm NR-17 which aims to establish parameters for adapting working conditions to the psychophysiological characteristics of workers, thus providing maximum comfort, safety and performance on the tasks. The ergonomic analysis was performed with the aid of Software "Ergolândia", which enables the investigation of work by several analysis methods in the literature. All parameters used for ergonomic analysis were based on observation of the workshop in which is performed the aluminum smelter, as well as the analysis of the video made that shows the accident mentioned in the analysis of the fault tree. 3.2 ANALYSIS NIOSH Factors that can be improved and consequently improve ergonomics during task execution. The approach employed to decrease the load the distance traveled by him between the origin and the place of deposition, using a counter to store the charge to a maximum height of 75 cm, the decrease of the angle of twist of the trunk of the operator, improving the quality of the handle with the use of pliers more anatomical hands, reducing the weight of the crucible to deposition of liquid aluminum, are factors that improve the index survey, therefore, would be more comfortable and less physically demanding from the point of view worker. Figure 6 shows part of the Database - Method NIOSH, in the role of Technical in the Workshop A of the Company X.
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop…
Figure 6 shows part of the Database – Method NIOSH
Figure 6 – Part of the Database - Method NIOSH 3.3 ANALYSIS OWAS (Orko work posture analysystems) The position of the back bent and knees flexed need to be reviewed and changed to ensure greater physical comfort while performing the task of lifting the crucible and dump the liquid aluminum sand mold. Regarding the position of the arms, are not necessary corrections in posture and / or changes in the working height of these members. Figure 7 shows part of the Database - Method OWAS, in the role of Technical in the Workshop A of the Company X.
Figure 7 shows part of the Database - Method OWAS
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop…
Figure 7 – Part of the Database - Method OWAS 3.4 ANALYSIS MOOR AND GAR The Strain Index (SI) is calculated by multiplying the parameters directly from FIT, FDE, FFE, FPMP, FRT and FDT. The SI of this activity is below 3,0 indicating that the activity is safe. As a suggestion of comfort for the worker who performs the task, it is suggested that the decrease in exercise time (FDE) and improves the position of the hand and wrist (FPMP). Figure 8 shows part of the Database – MOOR and GAR.
Figure 8 shows part of the Database – MOOR and GAR 3.5 CHECK LIST OF COUTO This method is a simplified assessment of biomechanical factor for risk assessment of workrelated upper limb. Sum of points equal to nine means a biomechanical factor of moderate importance, considered a risk unlikely but possible. Figure 9 shows part of the Database – CHECK LIST OF COUTO.
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop‌
Figure 9 shows part of the Database - CHECK LIST OF COUTO
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop…
Figure 9 – Part of the Database - CHECK LIST OF COUTO 3.6 ANTHROPOMETRY Anthropometry is defined as the set of methods to perform the measurements of the human body. It is essential to the design of workstations with sizes suitable to the employee. The software provides estimated measures of the human body based on height selected and recommended distances for work, such as arm's length and seat height. Figure 10 shows part of the Database – ANTHROPOMETRY.
Figure 10 shows part of the Database – ANTHROPOMETRY
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshop… IV.
CONCLUSION
The analysis presented in this work from the point of view of the Course Health and Safety at Work shows how extremely important to identify the risks involved in work activities. For it is through this identification that can map out a plan of risk control and eliminate hazards. From the identification of risk analysis is performed that allows categorization of the same, according to the occurrence probability and severity of impact. And to make this risk analysis, several methods have been developed, the best known being the Preliminary Risk Analysis (PRA), the Fault Tree Analysis (FTA) and the method HAZOP (Hazard Operability Analysis). In this work, we employed only the first two methods. Looking closely at the process of manufacturing parts for casting sand mold was possible to identify all the processes involved in manufacturing and the risks involved in each. With the risks identified was constructed table preliminary risk analysis, which presents risks categorized by type, its causes, effects and preventive measures adopted category. The fault tree analysis was developed based on an accident in the Workshop A of the Company X. This accident incurred severe burns technician manipulating the apparatus as well as moderate burns in two and a third light. By analyzing the accident, rose two hypotheses for the accident. The first involved the lack of hygiene and inspection of equipment used. The ingot in which the leftover liquid aluminum was deposited had not been properly sanitized and contained solid particles from welding or other activity involving steel performed in the same physical environment. These particles reacted with molten aluminum at high temperature (between 700 ºC and 800 ºC), causing the violent expulsion of the liquid metal. Another hypothesis to be considered, was cooling sudden liquid aluminum when in contact with the ingot due to the high coefficient of heat transfer due to the temperature difference between the liquid aluminum (between 700 ºC and 800 ºC) and the ingot at room temperature (between 20 ºC and 25 ºC) and also the material ingot high thermal conductivity (carbon steel). Another important point to be noted was the lack of use of Personal Protective Equipment (PPE) while performing the activity, which could have prevented the burns suffered by the technical workshop and also for other people. Ergonomics at work is governed by a Regulatory Norm NR-17 which aims to establish parameters for adapting working conditions to the psychophysiological characteristics of workers, thus providing maximum comfort, safety and performance on the tasks. The ergonomic analysis was performed with the aid of Software "Ergolândia", which enables the investigation of work by several analysis methods in the literature. Finally, the use of materials and techniques appropriate for each work activity can prevent many accidents.
REFERENCES [1]. [2]. [3]. [4]. [5].
[6]. [7].
[8].
Araújo, Suélio da Silva. Slides e Notas de Aula da Disciplina Higiene e Segurança do Trabalho. Universidade de Brasília, Distrito Federal, Brasil. Mattos, U. A. O. Higiene e Segurança no Trabalho. Rio de Janeiro: CAMPUS/ABEPRO. 2011. Siqueira, Milton Luiz. Slides, Seminários e Notas de Aula da Disciplina Tecnologia Mecânica 2. Chiaverini, Vicente, Tecnologia Mecânica, Volume II. Alves, M.B.M., Arruda, S.M. COMO FAZER REFERÊNCIAS: bibliográficas, eletrônicas e demais formas de documentos. Universidade Federal de Santa Catarina. Disponível em: < http://bu.ufsc.br/framerefer.html >. ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 6023: Informação e Documentação Referências - Elaboração. Rio de Janeiro: ABNT, 2000. Instituto Nacional de Metrologia, Normalização e Qualidade Industrial, Vocabulário internacional de termos fundamentais e gerais de metrologia, 3. ed. Rio de Janeiro, INMETRO, 2003. 75p., ISBN 8587090-90-9. Yamane, Alexandre Kenji; Souza, Luiz Gonzaga. APLICAÇÃO DO MAPEAMENTO DE ÁRVORE DE FALHAS (AAF) PARA MELHORIA CONTÍNUA EM UMA EMPRESA DO SETOR AUTOMOBILÍSTICO. <http://www.abepro.org.br/biblioteca/ENEGEP2007_TR580442_0041.pdf>Acesso em 08/05/2012.
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshopâ&#x20AC;Ś APPENDIX I
Stage
Preliminary Risk Analysis in the Manufacture of Cast Aluminum Parts using Sand Mold Type of Risk Cause Effect Category Risk Risk
Sand mixer
Mechanical
Inhalation of particulate sand
Chemical
Compacting the sand
Mechanical
Handling the sand in the mixer with the blades running
Type the sand / Not using mask
Injury / Fracture hands / fingers
Silicosis
III
III
Preparing of the mold
Transportation of sand and mold
Aluminium casting
Mold filling
With drawal part
Ergonomic
Instruments warm (oven, container and claw)
Physical
Pour the molten aluminum
Physical
Inhaling fumes from aluminum
Chemical
Carelessness / Disability handling tool Very heavy mold / Lack of "car" Lack of use of EPI / Improper disposal of instruments
Mishandling / Equipment failure Detachment gas aluminum
Lesion
Use powder desgaseificante
Burns / Vision Loss / Damage to Equipment
Physical
Connections / Hoses deteriorated
Explosion
Ergonomic
Transporting the mold/ Piece
Ergonomic
Use of very heavy container Lack of a "car"
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Improve organization / Use EPI
III
Gasleak
Transport container
Investment in equipment
Damage to the respiratory system
Lesion
Incorrect handling / Equipment failure
I
Training / maintenance
Use of very heavy container
Physical
Operator training
III
Ergonomic
Pour the molten aluminum
I
Burns / Damage to equipment
Transport container
Chemical
Use sand, silicon and mask
III
Physical
Excess aluminum / Lack of cleaning waste in ingot
Handling the sand with the mixer off
Burns
Over heating aluminum
Reaction between aluminum ingot and waste
Carelessness of the operator / Incorrect use of the oven
Fracture hands / fingers
Measures
Burns / Vision Loss / Damage to equipment
Burns / Damage to equipment
Lesion
Lesion
IV
Use of EPI / Use of most modern furnace
I
Investment in equipment
IV
Preventive maintenance
IV
Checking and cleaning of equipment prior / Use EPI
III
Training / maintenance
I
Investment in equipment
I
Investment in equipment
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshopâ&#x20AC;Ś APPENDIX II
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Analysis of the Working of Manufacturing of Parts by Foundry in the Workshopâ&#x20AC;Ś
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