اصلاح گوی مکان نما بر اساس ارزیابی ارگونومیک: یک مطالعه موردی در جامعه شناسی ارگونومی در اسرائیل

In 2001, production technicians at Intel's facility for manufacturing semiconductors in Kiryat-Gat began complaining of wrist discomfort and pain while using trackball work stations, the primary equipment for inputting data to their production environment. The complaints were received with considerable seriousness, indicating that the Incident Free Culture—a proactive attitude towards ergonomic matters—that had been created at the plant when it was established in 1997 had firmly taken root. The author of this paper, the plant's ergonomics engineer (EE), was authorized to deal with the problem but within very strict constraints. Production of the silicon wafers could not be interrupted in any way and the clean-room environment had to be maintained. The EE contacted the Department of Industrial Engineering at Ben-Gurion University in nearby Beer-Sheva and a two-part investigation program was devised to determine, within the limitations imposed by Intel, the source of the workers’ complaints. The first part of the program, a pilot investigation based on a sample of 20 technicians, indicated the need for extending the workstation's trackball angle from 9° to 24° to enable the technicians to work with their wrist in a more neutral posture. These results were subsequently confirmed by the main study involving 62 technicians divided into control and test groups. These results led to the implementation of the new trackball angle on all 900 workstations on the plant-manufacturing floor and became part of the baseline for future designs of all Intel plants worldwide. Intel's Incident Free Culture, the involvement of academia, and the immediate response to the subsequent ergonomic problems are all relatively new phenomena in Israel and an indication of the state of ergonomics in the country. In addition to the impact upon Intel plants themselves, both in Israel and abroad, the lessons to be drawn from these phenomena are being closely scrutinized by Israeli industry as well as various state bodies for further, more extended application.

At Intel's semiconductor manufacturing plant in Israel, an occupational ergonomic program was designed to create an ‘Incident Free Culture’ (IFC) on a plant-wide basis at the time of the plant's establishment in 1997. The IFC was a major ergonomic landmark for Israel at the time. Unlike many other programs that Intel and other Israeli firms have implemented through the years, this program was not established as a response to a high level of local injury rates, but was integrated into day-to-day work procedures. This ergonomics-based approach to developing a risk-free environment involved a radical change in the way employees and management regarded themselves in the context of their immediate work environment. The approach, which embraced the totality of the plant's social and cultural structure, led to the development of a mindset in which all employees became aware of the necessity for caring for their own and each other's health and well-being (Morag, 2005). A demonstration of the ergonomic mindset that had developed among workers and a major test of management's commitment to the IFC occurred in 2001 when the Occupational Health (OH) unit began receiving a number of complaints about wrist and hand pains. An initial survey conducted by the plant's ergonomic division indicated an increase in complaints, from, an average of, two to six a month, and the possibility that the discomfort and pain might be correlated with the use of the industrial workstation trackballs. Following the survey, several meetings were held with manufacturing management and OH. All were sympathetic to the discomfort the workers felt and the EE was given the green signal to launch a full-fledged study of the problem. However, it was stressed in the strongest possible terms that production could neither be interfered with, nor the clean-room environment compromised on. Silicon-wafer fabrication is conducted according to tight schedules and any disruptions would incur expensive penalties. The clean-room environment also imposed constraints upon the nature of the equipment that could be used. It was clear to all that any breach in the environment by the investigating team would also lead to unwelcome expenses. To cope with these issues, it was decided to consult the Department of Industrial Engineering at that nearby Ben-Gurion University. Consultations led to a decision to launch a two-phase project. The initial phase would focus on the industrial workstations and assess if they created a cumulative musculoskeletal physical load. If the indications suggested that the level of wrist discomfort was correlated to intense use of the workstation, a following study was to be performed to validate the pilot findings. 1.1. The workstation and the work task There are nearly 900 industrial workstations on the plant's production floor. Each includes a monitor, keyboard and trackball on its right-hand side (see Fig. 1). The workstation is the main interface between the technicians and technological environment and it is at the work station that the technician spends most of his or her time, operating the production process-flow, supervising the production machinery, monitoring the production quality, managing the inventory levels, etc. The trackball is an input device that is used to insert data through object pointing. At Intel plants worldwide, there has been a clear trend in recent years toward an increasing use of the trackball vs. the keyboard as an input device. The trackball lies at the heart of the work of some 1200 technicians at the plant. Their work routine consists of four 12-hour shifts—the first two being day shifts and the other two, night shifts. The technicians stand at their workstations for at least 9 out of 12 hours of each shift.

This sort of work, as reviewed here, has been cited in the literature as exposing technicians to ergonomic risks that can lead to soft-tissue injuries and disorders classed as MSD. Such disorders are frequently observed in the nerves, tendons, tendon sheaths, and muscles of the upper extremities of employees who perform hand-intensive jobs (Armstrong, 1990). Examples of MSD-related injuries include myalgia, tendonitis, tenosynovitis, and carpel tunnel syndrome (Grandjean, 1990; Keyserling et al., 1993). Although ergonomics, as an engineering field, is well-studied in the Israeli academic world, the awareness of ergonomics as a cost-effective catalyst to production efficiency and as a robust contributor to employees’ well-being barely exists among Israeli industrialists. Such is the degree of ignorance about ergonomics, that until now there has been no public cognizance that an employee might file a claim against an employer due to ergonomic injury. Indeed, governmental authorities do not collect or supply data on ergonomic work injuries and related costs. In brief, ergonomics is still being perceived as “nice to have” rather than a basic element of work. This attitude is now beginning to change due, in no small part, to the successful implementation of Intel's ergonomic program which has become a model for Israeli industry. The study was also a major affirmation for employees that management was still very much committed to maintaining an Incident Free Culture. The study takes on even greater significance when one considers that at the time the study was carried out, Israel was still in the depths of the hi-tech meltdown. Another particularly gratifying aspect of the program was that it was a cooperative effort between industry and academia. Following discussions betweens Intel's ergonomics division and the Department of Industrial Engineering at Ben-Gurion University, it was decided to use students to conduct the study. The use of students to carry out this proactive study was an “ergonomics first” both for Intel and the University. After the study was completed, the students presented the results at a major Israeli conference. This paper also demonstrates an applied ergonomic analysis performed in a unique industrial environment—the semiconductor production floor. The constraints associated with semiconductor production determined how the study was carried out. For example because of the high costs associated with interrupting the production flow, it was necessary to devise a minimally intrusive method for tracking the actions and movements of the technicians. Using video cameras, we were able to film postures and subsequently analyze them in a computerized format. Contrary to other methods generally used, this method made it unnecessary to physically mark joints or to use electronic devices attached to the subjects. In the study four assumptions were accepted; four were unfounded. 5.1. Assumptions accepted Assumptions 1, 2, 4 and 8 were accepted based on a comparison of the control and test group results. Assumption 1. When we changed the trackball angle from 9° to 24°, technicians were able to work with a smaller wrist extension, reducing the physical load on the wrist. Accordingly, the average level of discomfort was reduced in the test group (1.56–1.13), while discomfort increased in the control group during the same period of time (1.31–1.46). Burgess-Limeric et al. (1999) claim that continued exposure to a work posture that deviates from a neutral posture can cause musculoskeletal discomfort or pain. Our study also confirmed the model developed by Keyserling et al. (1993) and the findings of Rajendra and Chandra (1996) that a non-neutral posture exposes employees to potential ergonomic risks. Assumption 2. Increasing the trackball angle from 9° to 24° caused an average reduction of wrist extension in the test group from 34° to 26°. This change enabled the technicians to work with a posture within the neutral range. Our study confirms Keyserling et al. (1993) that any work performed within the neutral range (flexibility of the joint of up to 30°) should not cause discomfort or pain. Assumption 4. In the test group, the need to lean on the trackball device was reduced. Working with a limited wrist extension, which reduced the physical load, reduced wrist discomfort, thus reducing the tendency to use the trackball device as support. Two months after changing the trackball angle it was found that the leaning time was reduced significantly. Rajendra and Chandra (1996) found that the different design of input devices reflects differently in muscle activity. We have confirmed their study that device design influences musculoskeletal condition. Our findings show that the better design of the trackball device was responsible for reducing technician discomfort and thus their need to use the device for support. Assumption 8. Correlation between level of wrist discomfort and average wrist extension: the greater the extension, the greater the discomfort. The study found change between the groups. This result supports the study's basic assumption and confirms the findings of other studies in the literature. 5.2. Rejected Assumptions Assumptions 3, 5, 6 and 7 were rejected or proved unfounded based on a comparison of the control and test group results. Assumption 3. The video analysis showed no connection to the trackball angle in this case, because the time that a technician spends in each workstation is defined primarily by the tasks it requires. Assumption 5. By standing at a greater distance from the trackball, the taller technicians reduced their wrist extension. Since we did not define the standing distance from the workstation, the technicians stood in a place that enabled them to work with limited wrist extension. Assumption 6. We assumed that taller technicians will have greater wrist extension and the trackball angle change would reduce it. Instead, we found that by standing at a greater distance from the trackball, the taller technicians reduced their wrist extension. Assumption 7. The results suggest that heavy use and continuous work with a trackball that requires wrist deviation for nine hours a shift, four shifts a week is a not a major factor in wrist discomfort. The results of the main study showed that even though not all the pilot's recommendations were adopted by the plant management, because of operational constraints such as cost and the need to avoid fundamental changes in the work routine, a modest change in the trackball device has benefited the technicians’ comfort levels and reduced the frequency of complaints. Twelve months after the study, additional data were collected to examine the impact of the workstation's change. The data collecting method was similar to one used in the study (observations and questionnaires) and the subjects were asked about measures of comfort. Their answers were close to those collected 2 months after the modification. These data strengthen the conclusions, made after the study, that even this minor change in the workstation was found to be so effective that it was incorporated into Intel plants worldwide.