Ergonomic Work Analysis: A Study in a Sawmill Located on Southern of Brazil

Ergonomic Work Analysis: A Study in a Sawmill Located on Southern of Brazil

The wood and related products has a great economic and social importance on worldwide market. In the particular case of Brazil the sawmills present wide range of possibilities for ergonomic demands improvement. In this sense, the present study aims to investigate ergonomic conditions in a sawmill located on southern of Rio Grande do Sul, a Brazilian state. To this end, the study methodology consisted in application of field surveys, on-site observation and ergonomic analysis techniques. The results show the most critical job is the Hydraulic Carriage Drive (HCD)'s control, which demands an immediate improvement of postural conditions. Furthermore, we identified a few minor improvements necessaries on the work environment, including thermal comfort, noise and human-machine interface.

Keywords: RULA method, sawmills, ergonomic conditions

A company that wants to be competitive today need to focus their strategies for differentiating their products and processes without forgetting the concern with the quality of life of its employees, a fact essential for the company to achieve its goals. A particular case that deserves special attention is the timber industry due to its importance to the economy in the State.

The wood and its processing have always had economic importance for society. Despite the emergence of alternative materials and supplies, wood and its derivatives are even used widely and in important points of daily life in present societies (MARTINS e VIEIRA, 2004). The movement of the timber and related products markets has reached the 90 in the total value of $ 98 billion annually, of which 15% came from developing countries. This increase occurs both in products of lower value, such as the use of products that make greater use of technology. This growth trend, however, is more evident in products with higher technology and value. (NAHUZ, 2010). In this context, the Brazil is one of largest producers of wood, occupying the sixth position in reforested area and fourteenth position in forest cover, totalling approximately 540 millions of hectares. This gives it great advantages in the production of pulp, coal, lumber and wood panels, since it employs the advanced technology of cultivation, management and exploitation. It also has advanced technology in the planting of forests and a huge massive native forest with potential for economic exploitation. [15]. According to Brazilian Association of Planted Forest Producers (ABRAF – Associação Brasileira de Produtores de Florestas Plantadas) [1], in 2009 the florestal production of Brazil timber wood, sustainable forest production of timber in Brazil, originated from eucalyptus and pine forests, reached an estimated 250.3 million cubic meters / year. Between the two groups of tree species planted, eucalyptus represents 73% of the total sustainable production of timber while the pine is 27%. In Brazil, the total volume of wood produced in the forestry sector totaled around 100 million cubic meters, meaning an increase of 13 million cubic meters (15%) increase compared to reports in previous years. Regarding the state of Rio Grande do Sul the amount of timber produced is about 35 cubic meters per hectare per year. The particular case of Bagé city, the region covered in this study, data regarding the extraction of timber are 512 cubic meters per hectare per year [5].

The technique and art of woodworking have evolved over the years since the manual process and primitive to the vast and ingenious modern industry. Wood has always played an important role for society, since it was one of the first materials used by man for his defense, for warmth, cooking, shelter and even the construction of the first boats. Although the development of production technologies bring new materials, the use of wood and its derivatives continue to be used widely and in important parts of daily life in contemporary societies [10]. In this way, the present study aims to investigate ergonomic conditions in a sawmill located on southern of Rio Grande do Sul, a Brazilian state. Still, it carried out a discussion regarding the possibility of making improvements in working conditions and of process production performance under investigation.

A Wood and the Ergonomics
Many work situations and everyday life can bring harmful to health risks, among which we can mention the diseases of the musculoskeletal system, especially back pain, and those of psychological nature which together constitute the most important causes of absenteeism and of disability from work [3]. As causes for these prevalences are factors such as, for example, projects that ignore the human factor or incorrect use of equipment, systems and tasks. Such factors are addressed, and addressed by the Ergonomics and we can reduce them through this and so, improve working conditions and to obtain performance improvements. Finally, planning, design and evaluation of tasks, jobs, products, systems and environments is essential in order to make them more compatible and consistent needs, abilities and limitations of humans, thus being able to receive significant contributions from Ergonomics professionals.

The playing field of science in business is very broad, because where there is a human Ergonomics is present, and by analyzing the working conditions in areas that relate to physical, thermal, noise, lighting, vibration, posture, wear energy, stress, training, teamwork, organizational culture, workloads, aspects of materials handling, process or physical arrangement. In the specific case of labor activity, Iida [8] states that an employee can take hundreds of different positions, and each one a different muscle group is requested. It is the mobilization of these muscle groups that you get the strength to adopt a body posture or perform a movement. The ligaments, in turn, serve an auxiliary function, and the joints allow the displacement of parts of the body relative to the other (ULD and WEERDMEESTER, 2004).

Weerdmeester and Dull (2004) also emphasize that the understanding of posture and body movement is very important in ergonomics correction. Both at work and in everyday life these are determined by the nature of the task and the workplace. However, to remain at the same position for a prolonged period of time may cause localized pain in muscles and joints.

When looking at the particular case of the timber industry, you can find the working conditions that are inadequate for workers and leading to numerous instances of problems related to ergonomics. According to Souza et al. (2002), these processing industries occupy a prominent position on the frequency and severity of accidents, especially the type of damage caused to the worker, often permanent injuries, deaths and the long period of absence from work. The same author states that the wood industries are responsible for the third highest coefficient of frequency of fatal accidents in Brazil, second only to the industries of mining and construction industries. These coefficients can be easily reversed with the subsequent implementation of appropriate measurement and ergonomic analysis.

Any growth of wood-based production is based mainly on the improvement of the processes of industrialization of wood with increasing levels of technology, productivity, product quality and value. Some of the main industrial activities that use wood in general and in particular, and generate value-added products, technology and quality are in traditional activities, but which have great potential for improvement (NAHUZ, 2010).
The transformation of raw wood stemmed from planted forests as logs and is the main process performed by the timber, and these sites is to generate a large amount and diversity of waste. These, in most cases they are not used by the industry of primary processing (sawing) and secondary (processing) of wood, due to technological limitations or restrictions on the market. In the primary processing normally transforms the raw wood veneer on wood veneer. At this stage of processing, step sawmill has as the most characteristic products semiblocos, blocks, plates, beams, planks, and shingles. To obtain these products is used for circular saw, band saw or the like, to unfold, destopo or trim. In the second stage of processing using the products obtained in the primary processing for processing, such as the manufacture of gates, fences, windows, and similar materials.

In the cases cited above ergonomics correction can be applied aiming to solve security issues, excessive fatigue, illness of the employee, the quantity and quality in production. Many measures can be low cost and ease, such as postural changes, including security devices and increase in lighting, others may already be more complex and more expensive as a reduction in mental workload or replacement of machinery noise and inadequate (PRATES , 2007).

The great problem of the timber and furniture industries in terms of safety, according to Veras (2006), is the lack of investment by the company's adequate protection of machines. He explains that the legislation prohibiting the sale of machines without protective equipment has been breached as a way to reduce the costs of acquisition. For him, the argument does not justify the difficulty of importing, because there are already domestic machinery safe. Another critical point of the timber industry is related to lack of qualification, and most employees are trained by professionals older.

The union of these problems results in high rates of accidents, which according to Veras (2006) occur either because the worker is inexperienced, as in cases where accidents are caused by over-reliance on labor activity. The official statistics of occupational accidents in Brazil totaled 12,548 accidents between the years 2007 and 2008. In the division of economic activity relative to the unfolding of wood that cover the manufacture of lumber, veneer, plywood, pressed and crowded and wood products for construction, packaging, industrial, commercial and domestic, occurs at a rate of 137 accidents related to occupational diseases such as Repetitive Strain Injury and Work Related Musculoskeletal Disorders (RSI / WMSD).
The attribution of the fatality accidents is justified by ignorance or partial knowledge of the owners or leaders of the risks inherent to the activities, because it can be said that no fatal accident occurs. Accidents are caused by unsafe acts, unsafe conditions or by both factors together. Unsafe acts are practical procedures that contradict the safety standards, creating conditions for the accident happen. Accidents often result from inappropriate interactions between man, the task and its environment.

The particular case of occupational diseases, especially RSI and MSDs in the timber industry are serious problems, but the mutilation of fingers for lack of use of Personal Protective Equipment (PPE) and Equipment Collective Protection (EPC's) are the vast majority of accidents affecting many workers in this sector. One of the biggest causes of these accidents occur due to the pressure for productivity, which causes an increase in working hours and consequently mental and muscular fatigue (Veras, 2006).

Studies in the industry of sawmills in relation to health and worker safety in their work activities daily show, for example, it is important the leadership be aware of the importance of the use of PPE by employees, but only make them available not is enough since it is necessary to make them aware of the importance they have for their occupational health. Santos (2006), for example, mentions that the ratio of corporate social responsibility goes beyond meeting the legal requirements, to promote awareness of the employee and the employer to improve working conditions. He reports that awareness by owners in respect of PPE is critical, since they must have knowledge of labor legislation. Still, as shown Andrade et al. (2009), a major challenge in these locations is still just able to prevent, since in fact there are discrepancies between perceived health risks from the viewpoint of the employee and the employer.

Observing the timber industry, it identifies several working conditions inadequate to employees, and that leading to ergonomics problems occurrences. In this sites it can be verify the occurrence of occupational diseases, whereas RSI (Repetitive strain injury) and work-related musculoskeletal disorders (WMSD) are the most serious and frequent incidence. There are also the cases of mutilation of fingers due to absence or inadequate use of Personal Protective Equipment (PPE) and Collective Protection Equipment (CPE). These patterns of accidents are occurring more frequently with the workers of this sector. The pressure of productivity is the most frequent cause for accidents occurrence, as well as of the increase in working hours and also, of mental and muscular fatigue [17].

As causes for this prevalence it is verified factors as projects that ignore the human factor or the incorrect use of equipments, systems and tasks. These factors are treated and covered by the Ergonomic, which offers support to reduce them and thus improve the working conditions and it performance. In this sense, a critical point in wood industry, and specially sawmills, is lack awareness of the leaders about the importance to stimulate the use of PPE by the employees. Usually, the employer provides these devices only but do not explain to employees the importance of its use. Thus, social responsibility of business goes beyond complying of the legal requirements considering that, the owners' awareness in relation to PPE is a critical element [14]. In this way, one of the great obstacles in these companies is to provide incentives to the prevention, since in fact there are discrepancies between the health risk perception from the viewpoint of the employee and employer [2].

In this way, many actions can present a low cost and easy, for example, changes in posture, simple safety devices and increased lighting. Other cases may be more complex and result in increased costs as a reduction of mental fatigue, noise reduction and machines acquisition [13]. The great problem on wood industries in terms of safety, is the modest investment by the company in the adequate protection of machines, and the low-skilled worker. The combination of these problems, ultimately result in high levels of accidents [17].

In fact, the wood processing industries are characterized by the high frequency and severity of their accidents. These industries are responsible by the third highest rate of frequency of fatal accidents in Brazil, second only to the industries of mining and the civil construction industries [16]. These coefficients can be easily reversed using the performance measurements and the appropriate ergonomic analysis. However, despite the economic importance of this sector and the possibilities for performance improvements related to the implementation of ergonomic solutions, the implementation of improvements should be done sparingly so as to achieve adequate results with regard to adapting work to man. In turn, Guérin [4] states that such actions can be converted into gains by reducing of energy waste, quality improvement, cost reduction and increase of competitiveness. And, the planning, design and evaluation of tasks, jobs, products, environments and systems in order to make them compatible with the needs, abilities and limitations of people, are initiatives that can receive significant contributions from ergonomic professionals [7]. Thus, a study covering the analysis and understanding of work conditions in sawmills, can provide bases for future applications to improve the wellbeing workers and the performance of companies related to the wood industry.

Methodological Procedures
This study was carried using a Ergonomic Work Analysis method [4], which is applied for to analyze the tasks and activities, through of observational stages. Although this method is only suggested during the Ergonomic of correction of existent problems [8], in this study it application was utilized to support proposed improvements in Ergonomic Design. Therefore, we chose to use the phases:
1ª - Initial exploration and survey of ergonomic demands: Making the first visit to the company's locations, where it was possible to know the physical structure of the site, its key processes, mission, vision and values. In this step were approached both the business owner, and local the employees.
2ª - On-site observation: Were carried out at business place five visits utilizing random days and times. In these opportunities were collected images (photos and movies) and were applied unstructured interviews at owner e employees.
3ª - Postural analysis: Analysis of information obtained using mainly RULA (Rapid Upper Limb Assessment) method. This method allows us to observe and evaluate scores via appropriate tables with classification of problems related to neck, legs, trunk and upper limbs. Postural evaluation performed by this method begins by assessing the employee performing the work cycles several times. The score of the evaluated posture can be attributed considering the duration of the procedure, or taking into account the worst position maintained by the employee in performing the task [9].
4ª - Workplace job analysis: Concurrent with the on-site visits and postural analysis, was also observed and analyzed the layout of the place under study. At this stage it was defined the arrangement of processes, materials, equipment and personnel, including even its physical structure and its visual appearance to then relate it to working conditions.
5ª - Improvement proposes: Improvements were proposed at this stage, which were made available to the company through a report containing the study data. This document contained details of the suggestions for improvement, with guidelines for implementation.

The process under study
The site chosen for this study consists of a small sawmill that compared to patterns found sawmills in the region, has a competitive advantage in terms of technology. It was observed in the studied site that the job with a higher propensity for to occur postural ergonomic demands was the control operating of the Hydraulic Carriage Drive (HCD). This place centralizes the key processes performed of the company, which makes it the main equipment. Its physical structure is composed of electronic panel gauges, traction system to gauge of the wooden with 3CV motor-brake, pneumatic vacuum and wheels rolling. The segments taken from each timber log serve to give rise to different types of processing, resulting in products such as semiblocos, blocks, plates, beams, boards and battens. The waste is recovered to give organic fertilizers, firewood, and marketed for the manufacture of plywood. The function of the operator in this job is to operate the HCD using a step sequence is repeated several times until obtained the completed cut of the log.

The use of HCD allowed the process to be more productive and eliminated some of effort inherent in it. However, still remains in this workplace some risks to the health to the operator in his daily routine. Are examples, the monotony, the presence of unwanted noise, lumbar back pain and other muscular pains caused by injuries how tendinitis.

Ergonomic job analysis
By analyzing the job under study it was identified that the operator used predominantly the right side of his body to control operation of tge HCD. The main control of the machine is allocated on the right side. The commands of the equipment are not distributed uniformly and induce the operator to keep his body leaning forward and resting on your right. These factors strongly influence the occurrence of back pain, which in turn, often result from improper use of biomechanics and the ignorance of the limitations of the spine.

Postures as those seen in the position under study, can lead to anti-ergonomic conditions in the workplace, such as back pain (lumbar pain) and back pain (pain in the dorsal region), since many of these problems stem from incorrect use of biomechanics of the human machine and ignorance of the limitations of the spine. The main problem with this form of work, however, is not load on the muscles, but especially the wear of the spine, particularly in the lumbar intervertebral discs with the increased risk of disturbances.

In addition, there is no seat available to the operator, and he needs to use use a piece of tree trunk to sit in front of the panel. As a result, he needs to keep your torso (cervical and lumbar) in Isometric Muscle Contraction (IMC) and at angles that can lead to the occurrence of severe pains at the end of the workday. Nevertheless, the arms and forearms are also suspended during the entire period of operation of the machine, forcing the operator to make constant change of their positions to minimize the discomfort caused by IMC. The operator also stressed that he would feel better if I could perform the operation of the HCD lying in a plane approximately 50 cm above the plane of the rails where to move the logs. As aggravating postural conditions which the operator is subject, the conditions of the workplace also bring some significant challenges with regard to comfort, it is interesting for all companies to build sites that provide motivation and cooperation among its employees.

The ergonomic analysis using the RULA method revealed a significant wear of the operator according to their positions. The body side most compromised during their work activities is the right, which is the same of the operate control of HCD. The RULA analysis also reveals that while in the upper left side of the operator never reaches a score that requires postural changes (score 5 or more), the right limb most of the time (64%) requires postures that require urgent action. As an aggravating, the operator remains during most of the time that operates the machine (65%) under potentially harmful postures of the trunk, with scores between 4 and 6. The set of images in Figure 2 provides some examples that represent the postures imposed during operation of HCD.

When performing the joint analysis considering the limbs and trunk, according to the complete protocol provided by the RULA method, it was noted that the unfavorable trunk postures lead to a significant increase in the severity of the conditions imposed to the operator. In this case, and observing only the right side, it was noticed that at least 11% of the time the operator remains in postural conditions that require immediate action to improve its working conditions. 60% of the time during of their stay in station the operator keeps on conditions with class 2 or higher, and 40% of the time he is in a condition of class 3 and class 4, ie conditions which require carrying out investigations and immediate changes. A detailed analysis of the data reveals that the maintenance of trunk posture in IS is the main cause of the high scores identified by RULA. Even when viewing the left side, which proved to be less critical, the combined result of the combination trunk and limbs reveals the need for improvement actions. The graph in Figure 3 summarizes the results obtained by the RULA analysis.

Improvement proposals
According to the aspects identified during the research application is a clear need to carry out some actions to achieve improvements not only in the field of occupational biomechanics, but also related to the physical space and safety in the workplace.
Regarding the layout of the studied site and the general working conditions, it was observed that the space is ample facilitating the displacement of employees. However, the site is totally open and weakly protected from the wind, rain and excessive heat, which makes the environment uncomfortable for the worker. A suggested simple and low cost is to take advantage of the wood processed in the company itself to close part of the workspace and using the guidance of an expert, providing more comfort to employees, while protecting the logs preventing some are fully exposed to deteriorating agents such as variations in temperature and rainfall.

The environment under study offers daily a great number of risks to workers during the operation of machinery and equipment. The protection of these workers is legally required by the Brazilian regulatory norm NR 06 [11], which requires that the companies provide PPE to all employees. These equipments should be freely available, in perfect use condition and operation, and adequacy for the type of risk. The studied company fulfills its obligation, but not always the employees use the equipment. Thus, it is strongly recomend that the company not only complies with his duty, but that shows at their employees the importance of using the PPE.

The seat currently existing on site (trunk wood) should be replaced immediately because it does not have appropriate conditions (has no backrest, armrests, comfort and ideal height). According Dul and Weerdmeester [3], the seat height should have continuous adjustments and smooth rather than degrees adjusts. The optimum height is obtained when the thighs are well supported on the seat without crushing of the underside of thigh, and the feet are entirely supported on the ground. Thinking in this sense, according to the need of the operator, it is suggested that the company make the reuse of scrap wood crafting a chair for the employee's own timber, avoiding higher costs in purchasing materials. The ergonomic requirements are suggested: the backrest should provide support to the lumbar region (at the time of the abdomen), one should leave a clearance of 10 to 20 cm between the seat and backrest, the backrest should have a height of 30 cm (therefore the total height should be between 40-50 cm above the seat) one should not use the lumbar support to the back support in the case of a relaxed position, the lower backrest part (close to the seat) is to be convex to accommodate the curvature of the buttocks or may be hollow (the above recommendation, the size of the clearance must be adjustable between 10 and 20 cm between the seat and back).

For the human machine interface in the post studied, it is suggested to replace the current control lever for a more appropriate model. The adequate format of the command lever must include features that allow both large movements (low precision) and fine movements (high precision), occur so that does not require great effort by the operator, according the Figure 5. This change can be implemented easily by mechanical technician, it is not necessary constructive changes in HCD.

The function of the operator is of extreme importance in the company to require a lot of attention and responsibility on his part because it is the speed with which it controls the HCD that depends on the continuation of the work of other employees. If it is not being adequately controlled and if the operator fails to make the right decisions, it may be a serious accident involving several employees. This system of such complexity is known as Human-Machine System and means that the human and the machine maintains a reciprocal relationship. That is, a closed cycle where the human being has the key position, since it is he who makes the decisions. The process of information in the system are: the display conveys information about the progress of production, the operator must realize that information and understand it and read it correctly. Based on its interpretation and on previous knowledge gained, the human makes a decision. The next step is to communicate its decision to the machine through controls, and then processes the machine that was programmed. The control panel included key triggers and buttons that can continue to be driven by the fingers (low manual effort). However, the buttons and switches are arranged so that it can cause difficulties in interpretation and consequent risk of failure of operation. Thus, it proposes the use of logical ordering of space, using as reference the sequence of steps, HCD and process layouts.

Finally, the band saw is currently installed on the machine does not have any protection, being fully exposed to the worker, which creates a great risk of serious injury incidents. Therefore, it is proposed to construct a protective enclosure using wooden parts of the process itself. This is a low-cost and can be easily implemented by the company.

Discussion and Conclusions
The poll has a sample size of a medium sized timber consists of twenty employees who perform the procedure for processing of wood, with all its processes are semi automated control and requiring human strength, where a task is shared by a machine and a worker. It can be seen in the environment studied a number of peculiarities relating to respondents' perceptions of the risks. The responses highlight the need for attention to the sawmill industry in respect to the culture for occupational health and safety. In addition, activities aimed at raising awareness and training of workers in the region under study proved to be precarious.

As an aggravating factor, the implementation of efficient management programs in the productive sector of wood become difficult, mainly because of the low level of instruction of the population involved. In this sense, it is assumed that actions to improve cultural nature should be encouraged on a more comprehensive and collective communities connected with the timber companies in the region. This study contributes in this sense, showing that investments in ergonomics are important, since spending on sick employees, the loss of materialsthe delays in production and lack of motivation to work, due to working conditions and lack of training, are very significant in context of the business. Although it is often difficult to quantify the gains generated by the application of ergonomics in business, when a worker exposed to uncomfortable and embarrassing situations, harsh conditions that affect you physically or psychologically in their performance, and morale affected, resulting in impairment of the expected results.

By applying the suggested recommendations, it is estimated that the company will have the basic conditions for improving the working conditions of its staff and hence the productivity of their processes. With it, you can obtain the minimum conditions to improve their competitiveness and market positioning.

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