No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Ergonomic Study on the Manual Component Insertion Lines for Occupational Health and Safety Improvements
Abstract
The study aimed at reducing the occupational health and safety problems faced by the manual component insertion operators. Subjective and objective assessments, and direct observations were made in the printed circuit assembly factory. Simple and low-cost ergonomic interventions were implemented, that is, repairing chairs, reducing high workloads, assigning operators to a maximum of 2 workstations, confining machines that emitted bad smell and much noise, and providing finger work aids. The results of the interventions were reductions in operators' work discomforts, that is, chair discomfort (by 90%), high work stress, and discomfort due to profound change in their workstations. Their health hazards were also eliminated, that is, inhalation of toxic fumes, exposure to too much noise, and pain due to pressing sharp components.
... They studied how the different combinations of component bin arrangements and insertion sequences affected the number of errors (quality) and the assembly time (productivity). Sen and Yeow (2003a) conducted an ergonomics study in the manual component insertion (MCI) lines of a printed circuit assembly (PCA) factory for improvement in occupational health and safety (OHS) of the workers. The objective in the present research is to apply ergonomics methods on the MCI lines of a PCA factory for improvement in P&Q, increment in revenue, and reduction in rejection cost. ...
... Brown and Mitchell (1988) did an investigation into operators, engineers, and managers of PCA factories to determine the work environment parameters that inhibited their performance and they recommended opportunities to improve P&Q. Sen and Yeow (1999, 2001, 2003a and Yeow and Sen (1999a,b, 2000, 2002, 2003, 2004 presented how ergonomics was applied to the various processes of the PCA factories and the improvements attained in quality, productivity, and OHS. The PCA factory under study was a medium-sized multinational company, with a total revenue of about $US 14 million per month. ...
... However, these would remove the operators' unscheduled breaks, thus increasing their exposure to physical and psychological risk factors associated with work and exposure to injuries associated with those risk factors. A separate study to counter these effects was conducted by Sen and Yeow (2003a). In the study, the number of component types inserted by each operator was reduced, the conveyor speed was adjusted to suit the speed of operators' learning curve, the number of operator switchings to other workstations per day was reduced, and ergonomic finger work aids were given to operators to protect their fingers. ...
The study is aimed at improving productivity and quality, increasing revenue and reducing rejection cost of the manual component insertion (MCI) lines in a printed circuit assembly (PCA) factory. Subjective assessment (through questionnaire), direct observation method, and archival data were used. Live experiments were conducted on production lines. Eleven problems were identified, i.e., long search for materials from the stores, unproductive manual component counting, obstructions during insertions, component fall-off while the PCA board was traveling on a U-shaped conveyor, etc. Interventions were made to rectify the problems, i.e., to have only one central store to eliminate confusion of the materials’ whereabouts, use weighing scale for component counting, modify the MCI sequence and the bin arrangements to avoid obstructions, and use straight conveyor to reduce handling. As a result, there was a tremendous increase in productivity and yearly revenue (US956,136).
... They studied how the different combinations of component bin arrangements and insertion sequences affected the number of errors (quality) and the assembly time (productivity). Sen and Yeow (2003a) conducted an ergonomics study in the manual component insertion (MCI) lines of a printed circuit assembly (PCA) factory for improvement in occupational health and safety (OHS) of the workers. The objective in the present research is to apply ergonomics methods on the MCI lines of a PCA factory for improvement in P&Q, increment in revenue, and reduction in rejection cost. ...
... Brown and Mitchell (1988) did an investigation into operators, engineers, and managers of PCA factories to determine the work environment parameters that inhibited their performance and they recommended opportunities to improve P&Q. Sen and Yeow (1999, 2001, 2003a and Yeow and Sen (1999a,b, 2000, 2002, 2003, 2004 presented how ergonomics was applied to the various processes of the PCA factories and the improvements attained in quality, productivity, and OHS. The PCA factory under study was a medium-sized multinational company, with a total revenue of about $US 14 million per month. ...
... However, these would remove the operators' unscheduled breaks, thus increasing their exposure to physical and psychological risk factors associated with work and exposure to injuries associated with those risk factors. A separate study to counter these effects was conducted by Sen and Yeow (2003a). In the study, the number of component types inserted by each operator was reduced, the conveyor speed was adjusted to suit the speed of operators' learning curve, the number of operator switchings to other workstations per day was reduced, and ergonomic finger work aids were given to operators to protect their fingers. ...
An ergonomic study was conducted to improve the workstations for electrical tests in a printed circuit assembly (PCA) factory in an industrially developing country (IDC). Subjective assessment and direct observation methods were used on the operators to discover the problems in their workstations. The problems found were: (i) poor workstation design, (ii) mix-up of tested and untested boards, (iii) missing or incorrect test steps, and (iv) unclear pass/fail colour inspection criteria. Ergonomic interventions implemented were: (i) an improved workstation with space for resting arms and the oscilloscope and computer keyboards within easy reach of the operators; (ii) clear segregation of tested and untested boards to prevent mix-up; (iii) retraining of operators by more qualified trainers; and (iv) reference colour samples for more effective recognition of different colours in the projection screen. The results were average savings in yearly rejection cost (of US1100. The interventions implemented were simple and inexpensive but resulted in many benefits.Relevance to industryThe study will be beneficial, if repeated in other PCA or electronic factories in IDCs, in terms of improvements in quality, productivity and OHS of the workers, as most of them have similar manufacturing processes and equipment and poor awareness in ergonomics.
... Therefore, ergonomics and its benefits should be introduced to factories particularly in industrially developing countries (IDCs). In addition, many studies show that OHS can be improved using low-cost and simple (LCS) ergonomics methods and solutions [2,3,10,11]. These LCS methods and solutions are particularly useful for IDCs, which have limited funds, expertise and resources [12]. ...
... Ergonomics is new in IDCs [12], particularly in the electronics industry. Several ergonomics studies have been conducted in electronic motherboard factories in an IDC to improve OHS [1,2,3,10,11]. Several ergonomics studies have also been conducted in semiconductor factories in developed countries, e.g., Pocekay, McCurdy, Samuels, et al. conducted a study in a semiconductor factory in the USA and found inadequate equipment design and repetitive wafer-handling activities to be risk factors associated with musculoskeletal disorders for semiconductor industry workers [13]. ...
... Some ergonomics studies showed that LCS ergonomic interventions could be effective in preventing problems, e.g., Farhang and Michael [26] reported that a proper application of LCS personal protective equipment (PPE) could prevent up to 37.6% of occupational injuries and illnesses; Sen and Yeow [10,11] and Yeow and Sen [1,2,3] presented examples of LCS ergonomic interventions in manufacturing lines that succeeded in preventing OHS problems (e.g., workstation redesign, LCS process change and product redesign). Like in the present study, the LCS ergonomic interventions used included introducing PPE such as earplugs, minimizing the lead-frames cutting noise by covering the trim-form machines with high density plastic covers, raising floor level with metal platforms for die-bonding and wire-bonding, etc. ...
The study aimed to conduct an ergonomic intervention on a conventional line (CL) in a semiconductor factory in Malaysia, an industrially developing country (IDC), to improve workers' occupational health and safety (OHS). Low-cost and simple (LCS) ergonomics methods were used (suitable for IDCs), e.g., subjective assessment, direct observation, use of archival data and assessment of noise. It was found that workers were facing noise irritation, neck and back pains and headache in the various processes in the CL. LCS ergonomic interventions to rectify the problems included installing noise insulating covers, providing earplugs, installing elevated platforms, slanting visual display terminals and installing extra exhaust fans. The interventions cost less than 3 000 USD but they significantly improved workers' OHS, which directly correlated with an improvement in working conditions and job satisfaction. The findings are useful in solving OHS problems in electronics industries in IDCs as they share similar manufacturing processes, problems and limitations.
... In the manufacturing environments, various ergonomics studies have been conducted to bring improvements in human-machine interactions. These include (1) Steel Manufacturing Sector [1], (2) Automotive Sector [2][3][4][5][6], (3) Electronics Field [7][8][9], (4) Air Conditioning Field [10][11][12][13][14][15][16][17][18]. In this research, the authors extended their effort of finding ergonomic improvements in a medium-sized air handler manufacturing plant in terms of reducing workrelated musculoskeletal disorders (WMSDs) and other occupational health and safety (OHS) problems. ...
Graphical abstract Abstract This paper gives emphasis to an ergonomics study conducted in a fibre insulation bay of a medium-sized air handler manufacturing plant. Work-related musculoskeletal disorders and other health problems in the fibre insulator sheets cutting operations were closely looked into. Unstructured interviews were initially conducted to uncover the underlying problems, while Direct Observation (DO) and Participative Assessment (PA) methods were utilized to identify ergonomics risk factors. Ergonomics interventions by means of real life experiments were implemented. These included 1) providing semi leather gloves to replace cotton hand gloves, 2) providing plastic chairs with back rest for occasional sitting, and 3) installing a fiberglass rolling mechanism for fiberglass cutting on table top. Post survey incorporating both DO and PA methods was subsequently conducted to gauge its effectiveness in minimizing work-related musculoskeletal disorders and other health problems. This action-oriented study finally produced fruitful results which includedinsignificant low back pain and legs ache, minimized hand irritation sensations, relieved tiredness of operators, reduced nose irritation, eye itchiness, sore throat and dizziness.
... Companies aspiring to achieve competitive advantage do not force workers to adapt to their strenuous tasks, but seek to 'fit work to people' to improve human performance apart from other means of upgrading human well-being. In the manufacturing field, for example, various studies have been conducted to improve this human-machine interactions including (1) Automotive Sector [1, 2, 3, 4], (2) Electronics Sector [5], (3) Air Conditioning Field [6, 7, 8, 9, 10, 11, 12]. In this research, the authors chose to continue the effort of finding improvements in the manufacturing field in terms of reducing work-related musculoskeletal disorders (WMSDs) in an air conditioning equipment manufacturing factory. ...
This paper emphasizes an ergonomics intervention to fit jobs for workers in the handling of air handler panels in a manufacturing factory. Ergonomic risk factors were identified by means of qualitative and quantitative data from general survey, participative assessments, and direct observations. Ergonomics intervention via real life experiment was implemented. Post survey incorporating participative assessments and direct observations was subsequently conducted to gauge its effectiveness. This intervention comprises the introduction of a steel trolley for horizontal placing of steel panels and a mobile steel rack for vertical placing of those panels. This action-oriented study produced results which were in line with the objective of the research.
... This is a common limitation for research conducted in real life experiments as there are a limited number of subjects, e.g. Yeow and Sen (2003, 2004 and Sen and Yeow (2003a). Additionally, the research did not include reversals as such resourcing requirements were not available. ...
The study aimed to improve ergonomics, i.e. to increase productivity, quality, and work satisfaction of operators working in a harsh environment (i.e. freezer storage facilities) through the use of an audio feedback system. The operators’ job was to select ice-cream products from a distribution warehouse to fulfill customer orders. A field experiment was carried out to compare the conventional method (the use of paper pick list) and the new method (the use of an audio pick list system). The audio system included audio feedback which enabled the operator to verify the correct storage location before selecting product from its location. Results showed that the use of the audio system was more effective as productivity of picking task increased by 43%, quality improved through reduction of more than two-thirds picking errors, and work satisfaction increased as hand motions used in the paper pick list system with gloved hands were eliminated. The impact of this study suggests that harsh environments with similar work flows can be aided with an audio feedback system, weighing the costs and benefits of the system from the perspective of ergonomics, quality, and productivity.
... The present research was a part of a series of ergonomics studies in PCA factories in Malaysia, an industrially developing country (IDC), with the purpose of helping the industry (which is one of the biggest industries in the country) to improve quality, productivity and OHS [13,14,15,16,17,18,19,20,21,22]. The preliminary results of the study were presented in Yeow and Sen [20]. ...
An ergonomics improvement study was conducted on the visual inspection process of a printed circuit assembly (PCA) factory. The process was studied through subjective assessment and direct observation. Three problems were identified: operators' eye problems, insufficient time for inspection and ineffective visual inspection. These problems caused a huge yearly rejection cost of US 298,240 dollars, poor quality, customer dissatisfaction and poor occupational health and safety. Ergonomics interventions were made to rectify the problems: reduced usage of a magnifying glass, the use of less glaring inspection templates, inspection of only electrically non-tested components and introduction of a visual inspection sequence. The interventions produced savings in rejection cost, reduced operators' eye strain, headaches and watery eyes, lowered the defect percentage at customers' sites and increased the factory's productivity and customer satisfaction.
1276 weekdays, weeknights and weekends, and hence also resulting in neck disability. Males had a higher screen time compared to females but do not have a higher tendency for neck disability. Perceived neck discomfort increased exponentially along with the age. Therefore, this study showed that increased duration of screen time may cause both neck discomfort and neck disability.
The paper emphasizes an ergonomics intervention in a medium-sized manufacturing plant to fit jobs for workers with respect to the handling of steel panels for installation onto central station air handlers. Ergonomic risk factors were identified via qualitative and quantitative data obtained from general survey, participative assessments followed by direct observations. Ergonomics intervention by means of real life experiment was conducted. Post survey incorporating both direct observations and participative assessments was subsequently implemented to gauge its effectiveness. The intervention study comprises the introduction of a trolley designed for placing steel panels horizontally and a mobile rack created for upright placing of those panels. The action-oriented ergonomics study finally produced results which were in conformity with the research aim as anticipated.
This paper gives emphasis to an ergonomics study conducted in a fibre insulation bay of a medium-sized air handler manufacturing plant. Work-related musculoskeletal disorders and other health problems in the fibre insulator sheets cutting operations were closely looked into. Unstructured interviews were initially conducted to uncover the underlying problems, while Direct Observation (DO) and Participative Assessment (PA) methods were utilized to identify ergonomics risk factors. Ergonomics interventions by means of real life experiments were implemented. These included 1) providing semi leather gloves to replace cotton hand gloves, 2) providing plastic chairs with back rest for occasional sitting, and 3) installing a fiberglass rolling mechanism for fiberglass cutting on table top. Post survey incorporating both DO and PA methods was subsequently conducted to gauge its effectiveness in minimizing work-related musculoskeletal disorders and other health problems. This action-oriented study finally produced fruitful results which includedinsignificant low back pain and legs ache, minimized hand irritation sensations, relieved tiredness of operators, reduced nose irritation, eye itchiness, sore throat and dizziness.
Automated visual inspection (AVI) systems are playing important roles in ensuring manufacturing quality in the electronic industry especially in the assemblage of printed circuit boards (PCB). Most existing AVIs that are used for PCB inspection are categorized as non-contact inspection systems consisting of a single overhead camera. Such systems, which can be manual or automated, are incapable of detecting 3D pin-through-hole (PTH) component placement defects and reporting them. By considering an assembled PCB as a textured surface with a predefined depth map, we propose to apply an angled fringe projection to detect defects in PTH component placement. It has been found that angled fringe projection can be used for surface analysis by applying phase shifting and phase unwrapping obtained from several images. However, the turnover time for PCB inspection is very crucial in the electronic industry. In other words, an alternative improved method that speeds up the inspection process is always desirable. This paper describes a method of applying an angled fringe projection for 3D height measurement using a single captured image and a direct triangulation technique. The main focus of this paper has been made on the development of a fringe tracking algorithm and its practical implementation details. This algorithm allows us to obtain the depth map of the surface under analysis with just one image. The simulated data and calibration process of the tracking algorithm are discussed and an experimental result is given for Peripheral Component Interconnect (PCI) component insertion in computer motherboards. With proper system calibration and accurate image processing, we demonstrate the successful manipulation of a structured collimated light source for height measurement using a single captured image.
This article examines two manufacturing lines producing semiconductors using different technology concepts, namely Conventional Line (CL) and Lean Production Line (LPL). Both lines manufacturing the same products were compared using various factors, including working conditions, task risks and dangers of the job, and physical body stress. Ergonomic approaches were adopted in the investigation of the two lines. Survey questionnaires were administered to 30% of the workers, and multiple statistical tests were used to determine crucial predictors and to investigate the interactions between the factors. This research has shown that improved ergonomics factors will lead to better working conditions and thus increased job satisfaction. The observed ergonomic differences of these two production lines are compared, and appropriate managerial remedial action is recommended. The interventions to both the lines should reduce accident rates, minimize waste of resources, improve work effectiveness, and provide a better working environment that enhances employees' morale and maximizes productivity and profits. © 2010 Wiley Periodicals, Inc.
A survey was conducted on the efficacy of the Printed Circuit Assembly operations using newly designed Ergonomic Weighted Scores (EWSs) to evaluate Critical Instructions (CIs) to operators. This helped to choose priorities of problematic operations. Five EWSs were drafted, tried, and finalized by a team of experts, for the purpose of checking the adherence to CIs, failing any of which could cause adverse effects on the quality of products. The top three priority operations were identified and the follow-up studies resulted in an increase in monthly revenue of US$227,880 and improvements in quality, productivity, occupational health and safety of the operators. © 2003 Wiley Periodicals, Inc. Hum Factors Man 13: 41–58, 2003.
Unlabelled:
This article follows an earlier one in which four criteria and four bases for the development of an indirect-cost calculation model adapted to the accuracy requirements and time constraints of workplace decision-makers were established. A two-level model for calculating indirect costs using process mapping of the organizational response to a workplace accident is presented. The model is based on data collected in interviews with those employees in charge of occupational health and safety in 10 companies of various sizes in different industry sectors. This model is the first to use process mapping to establish the indirect costs of workplace accidents. The approach allows easy identification of the duration and frequency of actions taken by stakeholders when a workplace accident occurs, facilitates the collection of the information needed to calculate indirect costs and yields a usable, precise result. A simple graphic representation of an organization's accident processes helps the user understand each accident's cost components, allowing the identification and reduction of inefficiencies in the overall process.
Impact on industry:
By facilitating data collection and shortening the time needed to assess indirect costs of workplace accidents, this indirect cost calculation tool is better suited for workplace use than those currently available.
Occupational Health and Safety (OHS) stakeholders rarely factor the cost of workplace accidents into prevention spending decisions. The lack of consideration of this key information is related to the fact that the scientific literature has failed to provide OHS stakeholders with a cost-calculation tool that is both sufficiently accurate and does not require a data-collection stage ill-suited to the time constraints of workplace decision-makers.
This study reviews the recent literature to identify key elements that should foster the use of indirect-cost calculation methods by decision makers.
A "local" approach currently appears to be the best method for calculating indirect costs of workplace incidents or accidents in comparison to "bottom-up" or "top-down" approach. This paper discusses four criteria that this type of approach must satisfy to be compatible with the time constraints and accuracy demands of OHS stakeholders in organizations. In addition, four bases for the development of a new indirect cost estimation model are presented and discussed.
this study provides bases and criteria to help the development of indirect-cost calculation models better suited to workplace use than those currently available.
Recent advances in health risk reduction approaches are examined based on inter-country networking experiences. A noteworthy progress is the wider application of low-cost improvements to risk reduction particularly in small enterprises and agriculture in both industrially developing and developed countries. This is helped by the readiness of managers and workers to implement these improvements despite many constraints. Typical improvements include mobile racks, simple workstation changes, screening hazards, better welfare facilities and teamwork arrangements. In view of the complex circumstances of work-related health risks, it is important to know whether a low-cost strategy can advance risk reduction practices effectively and what support measures are necessary. It is confirmed that the strategy can overcome related constraints through its advantages. Main advantages lie in (a) the facilitation of improved practices in multiple technical areas, (b) the strengthening of realistic stepwise risk reduction, and (c) the enhanced multiplier effects through training of local trainers. Action-oriented risk assessment tools, such as action checklists and low-cost improvement guides, can encourage risk-reducing measures adjusted to each local situation. It is suggested to spread the low-cost risk reduction strategy for improving small workplaces in diversified settings with the support of these locally tailored tools.
The study aimed at reducing Printed Circuit Assembly (PCA) manufacturing problems, such as high production and customer rejects, occupational ill health and high labour content. Subjective assessments and direct observations were made in the manufacturing plant. The major problems were due to the Surface Mounted Technology Component Placement (SMTCP), the Manual Soldering (MS) and the Manual Cleaning (MC) processes. Previously, the SMTCP machines had difficulty in placing the Integrated Circuits (ICs) onto the pads due to the errors in the pad design, causing IC misalignment. The operators experienced difficulty in performing too much MS, which caused 13% component damage. The MC of the soldered areas of the PCAs caused headaches due to the smell of the solvent. Ergonomic recommendations were given and follow-up studies were conducted. The PCAs were redesigned to correct the pad design errors and to allow more components to be machine-soldered. This also reduced the labour content and the number of components being damaged during MS. Local suction chutes were installed to remove the MS fumes and solvent vapours. These interventions reduced the production rejects, improved productivity, improved occupational health and safety (OHS) and saved $US 581,495 on rejection cost per annum.
Workstations for Visual Inspections (WVIs) and also for Electrical Tests (WETs) of a multimedia product factory were studied from Ergonomic viewpoints. The problems, identified by subjective assessments and direct observations, were related to poor designs of workstations, work processes and improper tools, causing high (12.2 ± 4.1%) product returns. In some WVIs, operators were having visual fatigue due to excessive magnifying glass usage, glare from inspection templates and too many components to check within a very short period. Some WETs were not organised to reduce hands and body motions, and to eliminate confusing criteria for passing or failing of the tests. They also had poor visual projection tests due to too bright ambient illumination on the screen. The Ergonomic improvements were: the reduced usage of magnifying glass, the use of no-glare templates, visual inspection of only the electrically non-tested components, the re-design of WETs for economy of motion, the improvement on pass or fail criteria, dark space for effective visual projection tests, etc. These ergonomic interventions improved the company's productivity and operators' health, reduced the product returns and saved USD 70,900 per month.
In an earlier paper, the authors presented models of human functioning in visual inspection and derived optimal working speeds to balance the cost of time and the cost of errors. Both self-paced and externally paced models assumed a random search strategy. It was noted that choosing a standard speed for visual inspection is difficult with standard work measurement techniques and that the data required for the suggested search model are easily measurable. The purpose of this paper is to complement the earlier work by deriving similar models employing a systematic search strategy. The two models can be considered as bounds on actual performance; thus the current paper complements the previous one by establishing an upper bound rather than a lower bound on performance in search tasks. Comparisons between the two strategies are presented.
In the design of industrial inspection tasks, the assumption is usually made that human performance data collected in a 100% inspection scheme is valid for use when the inspector is engaged in sampling inspection. A direct test of this assumption using 60 student subjects showed it to be valid. Analysis of the inspection data in terms of stopping policy in selfpaced inspection showed close correspondence with a model of systematic visual search.
Training is a neglected area for improvement of industrial inspection performance. Previous work shows that training can be effective but provides the reader with general principles rather than detailed examples of training programs. The experiment reported here gives details of two training programs devised for a complex visual inspection task. They differed only in that one (active) required the trainee to make an active response at each stage, while the other (passive) did not. Task performance for 42 subjects in three age groups showed significantly better performance (fewer errors) with the active training program. The specific error types reduced by active training were those logically related to the training program. There was a significant age decrement in performance, but it was smaller in magnitude than the difference between training programs.
Aims to verify the effect on visual inspection performance as the number
of fault types increases and to investigate the main personality traits
of a competent inspector using factor analysis. Forty subjects
participated in the experiment. The performance measures were response
time and error rate. A significant effect was found when the number of
fault types increased. Four factors obtained by factor analysis
demonstrate that the personality of a competent inspector includes the
following characteristics: stability, enthusiasm, sensitivity, and
suspicion.
Little research has been done relating the layout of an assembly workplace in terms of the ‘zone of convenient reach’ (ZCR) to occupational health risks to the operators. Four groups of ten subjects were asked to assemble hacksaws under four experimental conditions. In three conditions subjects were free to arrange their own workplace, with each condition representing an improvement in terms of using a jig for assembly and being given instructions on proper use of the jig. The fourth condition used an ergonomically designed workplace where all parts were kept within the ZCR. Subjects had no practical experience in assembly work and were from non-engineering backgrounds. A video recording system was used to record the performance times, hand movements, body posture and strategies in assembling the hacksaw. Results showed significant learning between the first trial and the rest of the 20 trials for all the experimental conditions. The results also showed that an improved layout of the workplace would potentially produce the following benefits: (i) Reduced occupational health risks to the operator from back injury problems through safer use of hand movements and body posture. (ii) Increased productivity for the employer through more economical use of hand movements. Relevance to industryAn improved workplace design, achieved through use of an assembly jig, instructions on proper use of the jig and layout of components within the zone of convenient reach, can reduce work times and also reduce occupational health risks. Occupational health risks may be reduced by the operator having less contralateral movements and less use of two hands to pick single parts. Time is reduced through use of more simultaneous motions.
An abstract is not available.
Records of the performance of a group of on-line inspectors of glass items over a ten month period were analysed using the Theory of Signal Detection. It was found that the inspection group as a whole followed the theoretical predictions. The introduction of more rapid feedback of performance to the inspectors after twelve weeks of the study increased the effective detectability of the faults significantly, reducing the percentage of missed faults by half. The effect of input quality level on performance before and after the change was studied. The usual drop in fault detection performance with increased quality was found and analysed to show that the inspection group were attempting to keep the outgoing percentage defective constant.
This article presents an approach to workload modeling of manufacturing workers using fuzzy set theory. Inspectors of integrated circuit boards in an electronic manufacturing system were observed for 9 months. Two types of inspectors were observed: novice inspectors with an average of 1.8 years and experts with an average of 26.5 years of experience. Data were collected on judgment, perception, and attention tasks. The inspectors were given subjective self-evaluation tests to capture the level of workload experienced in each of the task categories. The data were transformed into fuzzy membership functions and were used to quantify workload metrics and inspectors' performance. © 1999 John Wiley & Sons, Inc.
A survey was conducted on the efficacy of the Printed Circuit Assembly operations using newly designed Ergonomic Weighted Scores (EWSs) to evaluate Critical Instructions (CIs) to operators. This helped to choose priorities of problematic operations. Five EWSs were drafted, tried, and finalized by a team of experts, for the purpose of checking the adherence to CIs, failing any of which could cause adverse effects on the quality of products. The top three priority operations were identified and the follow-up studies resulted in an increase in monthly revenue of US$227,880 and improvements in quality, productivity, occupational health and safety of the operators. © 2003 Wiley Periodicals, Inc. Hum Factors Man 13: 41–58, 2003.
This paper describes the results of an ergonomics field study in a manufacturing environment. The study was performed primarily to improve the manufacturing yield in the production of electronic circuit board panels. A secondary objective was to improve operator comfort and job satisfaction. The project combined ergonomics and productivity assessments of several different tasks using analysis methodology such as ergonomic check lists, predetermined time and motion study operator assessment of ergonomic interventions and the rate of absenteeism. The project revealed a 16,000. This implies a hundred-fold rate of return of invested funds.
This paper describes the increasing emphasis on ergonomics in the manufacturing plants of IBM. Since 1978, 250,000 engineering hours have been devoted to ergonomics training. As a result a systematic approach to ergonomics improvement of manufacturing facilities has been implemented. This involves an analysis of the production environment including equipment, processes, ambient factors and job procedures. Information is collected through interviews of management, operators, and first-line supervisions, and complemented thorough field measurements of ergonomic parameters. Individual workstations as well as processes are analyzed with the purpose of modifying processes, reallocating tasks between automated devices and human operators and optimizing workstation design. Four case studies of industrial improvements are presented and analyzed in terms of improved productivity, quality, and reduction of injuries. All four studies proved to be good investments. Since its implementation around 1978, it is estimated that ergonomics improvements have resulted in cost savings of approximately $130 million.
The purpose of this case study was to identify the work cycles imposing high loads on the upper limb and low-back among trailer assembly workers for an ergonomic intervention. Several changes in work methods, tools and work organisation were implemented. The number of repetitions of fundamental work cycles and wrist posture were recorded from the video. Exposure imposed on the upper extremity in driving screws and drilling was computed based on experiments on force and time requirements. In lifting or carrying, the dose imposed on the lowback was computed based on the load moment on the L5/S1 disk and duration of the cycle. It was shown that after the intervention most workers worked less with deviated wrist and the cumulative exposure on the upper extremity was lower in furniture fixing tasks. Lifting with twisted torso was reduced. It was concluded that with relatively simple and low-cost solutions exposure to important risk factors of upper extremity and low-back disorders could be reduced.
An ergonomic study was conducted to improve the workstations for electrical tests in a printed circuit assembly (PCA) factory in an industrially developing country (IDC). Subjective assessment and direct observation methods were used on the operators to discover the problems in their workstations. The problems found were: (i) poor workstation design, (ii) mix-up of tested and untested boards, (iii) missing or incorrect test steps, and (iv) unclear pass/fail colour inspection criteria. Ergonomic interventions implemented were: (i) an improved workstation with space for resting arms and the oscilloscope and computer keyboards within easy reach of the operators; (ii) clear segregation of tested and untested boards to prevent mix-up; (iii) retraining of operators by more qualified trainers; and (iv) reference colour samples for more effective recognition of different colours in the projection screen. The results were average savings in yearly rejection cost (of US1100. The interventions implemented were simple and inexpensive but resulted in many benefits.Relevance to industryThe study will be beneficial, if repeated in other PCA or electronic factories in IDCs, in terms of improvements in quality, productivity and OHS of the workers, as most of them have similar manufacturing processes and equipment and poor awareness in ergonomics.
Whereas knowledge of results (KR), that knowledge received on the outcome of one's responses, has been shown to facilitate learning of visual search in inspection, further research is required to determine its influence upon decision-making, the other aspect of inspection. Twenty subjects, randomly assigned to either a KR or No-KR group, performed a visual inspection task; defect probability and discriminability were manipulated within subjects, and sequence of discriminability levels was manipulated between subjects. Via a signal detection model interpretation, KR increased sensitivity but had mixed effects on response criterion. The sensitivity changes were interpreted via attention theory, and a cognitive model of KR utilization was presented.
We have determined the transverse chromatic aberration of the human eye by measuring the apparent offset of a two-color vernier viewed foveally through a displaced, pinhole aperture. For the same subjects, we also determined the longitudinal chromatic aberration for foveal viewing by the method of best focus. In both cases, the results were closely predicted by a simple, reduced-eye optical-model for which transverse and longitudinal chromatic aberration are directly proportional, with the constant of proportionally being the amount of displacement of the pinhole from the visual axis. Further measurements revealed that the natural pupil was closely centered on the visual axis for two subjects and slightly displaced in the temporal direction for three other subjects. One implication of these results is that, although the eye has substantial chromatic aberration, the pupil is positioned so as to minimize the transverse component of the aberration for central vision, thereby optimizing foveal image quality for polychromatic objects.
Dittmar, Warm, and Dember (1985) suggested that visual parallax may lead to declines in perceptual sensitivity over time in spatial vigilance tasks involving comparative judgments. The present study tested this possibility by restraining subjects' head movements during a 1-hr vigil in which comparative (simultaneous task) or absolute (successive task) judgments of line length were necessary for signal detection. Under free-viewing conditions, perceptual sensitivity declined over time with both types of tasks. Head restraint eliminated the sensitivity decrement in both cases. The results highlight signal quality as a crucial determinant of perceptual decrements in sustained attention.
EVALUATED, SINGLY AND IN COMBINATION, THE EFFECTIVENESS OF A 4-HR TRAINING PROGRAM AND A SET OF VISUAL AIDS DESIGNED TO IMPROVE THE PERFORMANCE OF 27 EXPERIENCED MACHINED-PARTS INSPECTORS. THE CRITERION WAS THE PERCENTAGE OF DEFECTS DETECTED IN A SAMPLE OF MACHINED PARTS. USE OF TRAINING ALONE RESULTED IN A 32% INCREASE IN DEFECTS DETECTED, WHILE USE OF VISUAL AIDS ALONE RESULTED IN A 42% INCREASE. USE OF BOTH RESULTED IN A 71% INCREASE, WHILE PERFORMANCE OF THE CONTROL GROUP DID NOT CHANGE. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The disc pressure of the third lumbar disc and the myoelectric activity of several muscles of the back caused by sitting in an office chair were investigated simultaneously in three subjects. The backrest was located either at L 4 to 5 level or at L 1 to 2 level. The knee angle was either 90°, or the legs were crossed. The table surface was either 28 or 21 cm above the surface of the seat. The studies covered upright sitting, sitting with the back dorsiflexed over the backrest and 4 sedentary tasks: writing, typewriting, depression of pedal, and lifting a weight of 1.2 kg. The work activity was of greater influence than a change in table height or in location of the backrest. In upright sitting the highest level of myoelectric activity was found in the thoracic region. The disc pressure when sitting upright was lower when the backrest was located at L 4 to 5 level than at L 1 to 2 level. The myoelectric activity and the disc pressure both decreased when writing and increased when typewriting and lifting. The lowest pressure was obtained when the back was dorsiflexed over the backrest. It is concluded that the position of the backrest and the vertical distance between the seat surface and the table surface should be capable of variation. The height of the table surface above the seat surface should be less when typewriting than when writing.
An awkward and static work posture has been recognized as a risk factor for work-related musculoskeletal problems. The objective of this study was to investigate some of the factors that can influence the posture adopted during work and in particular aspects of the task and how their influence is affected by work height. Three types of task were studied: a peg-hole assembly task, which was largely manual with very little visual component; a visual character identification task; and a combination of the two. Two levels of difficulty were included in each of the manual and visual elements. Postures of the head/neck, trunk and arm were recorded during performance of these tasks. The results showed that type and difficulty of task do influence the posture adopted, and that some of the postural responses (although complex) are predictable so that poor postures could be improved by adjusting task design in addition to workplace layout.
Feedback of information has consistently shown positive results in human inspection, provided it is given in a timely and appropriate manner. Feedback serves as the basis of most training schemes; traditionally this has been performance feedback. Other forms of feedback which provide strategy information rather than performance information may have a role in improving inspection. This study compared performance feedback and cognitive feedback in a realistic simulation of an aircraft structural inspection task. Performance (time, errors) feedback showed the greatest improvements in performance measures. Cognitive feedback enhanced efficiency measures of search strategy. When cognitive feedback consisted of visual representations of the path and the coverage of the search sequence, subjects also were able to use this task information to improve their search performance.
A case study to illustrate the cost effectiveness of ergonomic redesign of electronic motherboard was presented. The factory was running at a loss due to the high costs of rejects and poor quality and productivity. Subjective assessments and direct observations were made on the factory. Investigation revealed that due to motherboard design errors, the machine had difficulty in placing integrated circuits onto the pads, the operators had much difficulty in manual soldering certain components and much unproductive manual cleaning (MC) was required. Consequently, there were high rejects and occupational health and safety (OHS) problems, such as, boredom and work discomfort. Also, much labour and machine costs were spent on repairs. The motherboard was redesigned to correct the design errors, to allow more components to be machine soldered and to reduce MC. This eliminated rejects, reduced repairs, saved US dollars 581495/year and improved operators' OHS. The customer also saved US dollars 142105/year on loss of business.
Information processing in vigilance performance: complexity revisited
- J S Warm
- W N Dember
- T M Lanzetta
- J C Bowers
- R J Lysaght
Warm JS, Dember WN, Lanzetta TM,
Bowers JC, Lysaght RJ. Information
processing in vigilance performance:
complexity revisited. In: Swezey RW,
editor. Progress for people: proceedings of
the Human Factors Society 29th Annual
Meeting, Baltimore, MD. Santa Monica,
CA, USA: Human Factors Society; 1985.
vol. 1, p. 19-23.
Effects of auxiliary load on vigilance performance in a simulated work environment
- J S Warm
- R R Rosa
- M J Colligan
Warm JS, Rosa RR, Colligan MJ. Effects of
auxiliary load on vigilance performance in a
simulated work environment. In: Perspectives.
Proceedings of the Human Factor Society
33rd Annual Meeting, Denver, CO. Santa
Monica, CA, USA: Human Factors Society;
Laboratory experiment: Human error at visual search of circuit boards
- A Bossemeyer
Bossemeyer A. Laboratory experiment:
Human error at visual search of circuit
boards. Z Arbeitswiss 1998;52:56-61.
Ergonomic study on printed circuit assembly lines for better productivity and quality
- R N Sen
- P H P Yeow
Sen RN, Yeow PHP. Ergonomic study on
printed circuit assembly lines for better
productivity and quality. In: Hanson MA,
Lovesey EJ, Robertson SA, editors.
Contemporary Ergonomics 1999. London,
UK: Taylor & Francis; 1999. p. 38-42.
Solving dropout problems in a printed circuit assembly line
- P H P Yeow
- R N Sen
Yeow PHP, Sen RN. Solving dropout
problems in a printed circuit assembly line.
In: Straker L, Pollock C, editors. Proceedings
of CybErg 1999: The Second International
Cyberspace Conference on Ergonomics.
Perth, Australia: International Ergonomics
Association Press, Curtin University of
Technology; 1999. p. 698-710.
Quality, productivity, occupational health and safety, and cost effectiveness of 5 ergonomic studies in electronic factories
- Php Yeow
- R N Sen
Yeow PHP, Sen RN. Quality, productivity,
occupational health and safety, and cost
effectiveness of 5 ergonomic studies in
electronic factories. In: Proceedings of the
Nordic Ergonomic Society's 34th Annual
Congress, Kolmården, Sweden, October
1-3, 2002. Linköping, Sweden: Linköpings
Universitet. p. 847-52.
Evaluation of human work-A practical ergonomics methodology
- M A Sinclair
Sinclair MA. Subjective assessment. In:
Wilson JR, Corlett EN, editors. Evaluation
of human work-a practical ergonomics
methodology. 2nd ed. London: Taylor &
Francis; 1995. p. 69-100.
Evaluation of human work-a practical ergonomics methodology
- P A Howarth
Howarth PA. Assessment of the visual
environment. In: Wilson JR, Corlett EN,
editors. Evaluation of human work-a
practical ergonomics methodology. 2nd ed.
London: Taylor & Francis; 1995. p. 445-82.
Visual search in industrial inspection
- C G Drury
Drury CG. Visual search in industrial
inspection. In: Brogan D, editor. Visual
search. London, UK: Taylor & Francis; 1990.
p. 263-76.
Evaluation of human work-a practical ergonomics methodology
- M A Bullimore
- P A Howarth
- E J Fulton
Bullimore MA, Howarth PA, Fulton EJ.
Assessment of visual performance. In:
Wilson JR, Corlett EN, editors. Evaluation
of human work-a practical ergonomics
methodology. 2nd ed. London, UK: Taylor
& Francis; 1995. p. 804-39.
Auditory environment and noise assessment
- C M Haslegrave
Ergonomic evaluation of work and environment on technicians working in a multimedia chip manufacturing industry in Malaysia
- R N Sen
- Y H Quek
Subjective assessment
- M A Sinclair
Posture improvement due to changes in an electronic component manual insertion workstation: A case study
- J Wick
Reducing the probability of ergonomics related injuries in manufacturing
- C Herring
- J L Wick
Evaluation of human work-A practical ergonomics methodology
- C M Haslegrave