Assembly Jobs Research Articles

Promoting Job Safety for Workers with Intellectual Disabilities: The Staying Safe at Work Training Curriculum

In the United States, approximately 125,000 people with disabilities are employed through Community Rehabilitation Programs in manufacturing, assembly, and service jobs. These jobs have significant hazards and, consequently, the workers are at risk of injury. Training that empowers workers to participate in prevention efforts can help reduce work-related injuries. In general this kind of health and safety training in the United States is limited. It is even more so for workers with intellectual disabilities, in part because there have not been programs for teaching individuals with cognitive challenges health and safety skills, adapted to their learning needs. This paper describes the development and promotion of the Staying Safe at Work curriculum of UC Berkeley's Labor Occupational Health Program, which is designed for use by support agencies and employers of workers with intellectual disabilities. The goal of this program is to teach these workers essential occupational safety and health skills in a manner they can understand.

Work Variations and Musculoskeletal Stresses in Paced Production Operations

This study aimed to test the hypothesis that variations in assembly jobs increase workers’ exposure to risk factors for musculoskeletal disorders. Variations can be caused by different factors such as, materials, material placement, product variety, work flow, etc., and they can require the worker to perform movements not considered in the calculation of the allocated time. Work variations may require workers to work faster and longer to keep up with paced work, which may increase repetition and reduce recovery time. On a moving line, workers may have to reach further to keep up with the work, which requires additional time and results in posture stress. An observational study was conducted in a moving assembly line where food trays were prepared for patients at a large hospital to test the proposed hypothesis. Frequency and quantity of work variations, and the frequency of reaching outside of the reach envelope and recovery time were compared. The variety of materials (along with their location), interar...

Forced to Concede: Permanent Restructuring and Labour's Place in the North American Auto Industry

Abstract: The stunning decline of Ford, General Motors and Chrysler over the past decade has rendered the once “Big Three” US automakers a vulnerable “Detroit Three”. In their attempts to return to profitability, the Detroit Three have undertaken a series of “turnarounds” aimed at renewing their competitive edge. Through this corporate restructuring agenda, 250,000 assembly jobs in North America have been lost, upwards of 50 auto plants have been closed, wages and benefits for new hires have been cut substantially and once strong, independent auto unions have been thoroughly overwhelmed. Permanent restructuring, then, represents a crisis strategy on the part of the corporate elite to continually intensify the demands placed on labour in the hopes of creating new conditions for capital accumulation. Working within labour geography, this paper documents the “regional race to the bottom” in the North American auto industry while reminding labour geographers that capitalist restructuring is a powerful constraint on labour agency.

Shoulder loading while performing automotive parts assembly tasks: A field study

The purpose of this study was to complete in depth task analyses for a series of automobile parts assembly jobs and quantify the range of mechanical shoulder loading sustained by the workers. Nine jobs were selected from within an automobile parts assembly plant and 26 participants (12 males, 14 females) were filmed while they performed regular assembly line duties. Workers spent the majority of their time in neutral shoulder postures, and about 1/3 of the shift in mild shoulder flexion or abduction. Cumulative shoulder flexion moments ranged from 76–160 kNm*s while cumulative shoulder abduction moments ranged from 42–119 kNm*s. Peak shoulder flexion moments ranged from 26–124 Nm and peak shoulder abduction moments ranged from 30–93 Nm. The analysis revealed a wide range of shoulder loading between jobs, and workers completing the same job. This study demonstrates the importance of measuring a variety of postural and mechanical demands for every job to adequately address all aspects of the work that might influence the development of injury. This is the first study to document entire shift cumulative shoulder moments during automotive parts assembly work. This quantitative assessment provides insight into the range of loading that workers are currently experiencing, and demonstrates the variability between workers completing the same task.

Comparing polymer optical fiber, fiber Bragg grating, and traditional strain gauge for aircraft structural health monitoring

Systems for structural health monitoring in aeronautical structures use methods of measuring the elongation that normally require too heavy setups or difficult assembly jobs, such as those based on traditional strain gauges. Alternative methods based on fiber Bragg gratings tend to be very expensive. We analyze the possibility of improving the existing designs with the aid of low-cost plastic optical fiber sensors. For this purpose we test these sensors in a rudder flap subjected to different types of bending forces. The results show that they offer good stability and repeatability, and the measured values are very similar to those obtained with Bragg sensors.

Foot motions in manual material handling transfer tasks: A taxonomy and data from an automotive assembly plant

Ergonomic job analysis commonly applies static postural and biomechanical analysis tools to particular postures observed during manual material handling (MMH) tasks, usually focusing on the most extreme postures or those involving the highest loads. When these analyses are conducted prospectively using digital human models, accurate prediction of the foot placements is critical to realistic postural analyses. In automotive assembly jobs, workers frequently take several steps between task elements, for example, picking up a part at one location and moving to another location to place it on the vehicle. A detailed understanding of the influence of task type and task sequence on the stepping pattern is necessary to accurately predict the foot placements associated with MMH tasks. The current study examined the patterns of foot motions observed during automotive assembly tasks. Video data for 529 pickup and delivery tasks from 32 automotive assembly jobs were analysed. A minimum of five cycles was analysed for each task. The approach angle, departure angle, hand(s) used, manipulation height and patterns of footsteps were coded from the video. Object mass was identified from the job information sheet provided by the assembly plant. Three independent raters coded each video and demonstrated an intraclass correlation coefficient of 0.54 for identification of the configuration of the lower extremities during terminal stance. Based on an analysis of the distribution of stepping behaviours during object transitions (pickups or deliveries), a transition classification system (TRACS) was developed. TRACS uses a compact notation to quantify the sequence of steps associated with a MMH transition. Five TRACS behaviour groups accounted for over 90% of the transition stepping behaviours observed in the assembly plant. Approximately two-thirds (68.4%) of the object transfers observed were performed with only one foot in contact with the ground during the terminal posture. The results from this paper suggest that a predictive model for choosing a transition stepping behaviour, coupled with a model to scale the selected foot behaviours, is needed to facilitate accurate prospective ergonomic analyses. This study proposes a method for categorising the stepping patterns associated with MMH tasks. The influence of task type and task sequence on the stepping patterns observed during several automotive assembly tasks is discussed. For prospective postural analyses conducted using digital human models, accurate prediction of the foot placements is critical to realistic postural analyses.

A scheduling problem for PCB assembly: a case with multiple lines

A production scheduling problem for printed circuit board (PCB) assembly with multiple lines is addressed. The investigated problem is to schedule a set of PCB assembly jobs with different ready times and due dates on multiple assembly lines, with the objective to minimize the sum of total weighted tardiness of jobs and weighted makespan. The feature that each job can be completed by different lines with different process times makes the problem a special type of unrelated parallel-machine scheduling problem (PMSP) with special constraints and a unique objective. A mixed-integer linear programming model for the problem is established and verified through solving some small-sized problem instances to optimality. In order to solve the real-world problems, a steady-state genetic algorithm with an improved replacement strategy is proposed. Experimental tests and a case study are conducted to examine the usefulness and effectiveness of the approach.

Musculoskeletal disorders in assembly jobs in the automotive industry with special reference to age management aspects

Production planners in the automotive industry are already being confronted with the problem of steadily increasing age of workers performing assembly jobs which frequently involve highly repetitive, short-cycle operations, and this problem seems likely to become more acute in the future. Two diametrically opposed solutions are being used: (1) Older workers are phased out under early retirement schemes (before musculoskeletal problems arise), and preference is given to younger workers, in many cases on a temporary, subcontracted basis. (2) Ergonomic and medical danger points in assembly processes are identified and eliminated by modification of the work model, irrespective of whether older or younger workers are involved. The results of a case study at 256 work stations on an assembly line for middle class cars manufactured by a globally active corporation are reported. The following interactions were noted: The age of the assembly workers influences the choice of workplace. Older workers are to be found mainly in jobs with a ‘very favourable’ expert rating, younger workers in jobs with ‘(very) unfavourable’ ratings. Accordingly, age and job strain are in this case not independent variables. Older workers still complain of lumbar spine symptoms despite low demands imposed by their present jobs. This seems to indicate long-term cumulative effects. A major aspect however is that the spine symptoms are often induced multifactorial and rely not or not alone on work conditions. Head–neck–shoulder symptoms occur more frequently in older workers working under unfavourable conditions. Symptoms affecting the head–neck–shoulder region, the lumbar spine and the upper limbs are co-variable with body height and body mass index. For the collective study, it was appropriate to avoid potential impairment of physical performance more or less completely by allotting jobs causing less strain to older workers. Relevance to industry The current study provides the results of a field study of assembly jobs in the automotive industry concerning the relationships between workload, age and musculoskeletal symptoms as well as diverse subjective measures (job satisfaction, etc.).

A Randomized Controlled Trial of a Supported Employment Program for Persons With Long-Term Mental Illness in Hong Kong

A Randomized Controlled Trial of a Supported Employment Program for Persons With Long-Term Mental Illness in Hong Kong

A general approach to grouping of PCB assembly jobs

Ordering of batches of printed circuit boards (PCBs) has a significant impact on the efficiency of the electronic component placement processes. Through PCB batch grouping we aim to minimize the total setup time between batches. Batch groups are formed so that each group can be handled with one component setup. The job grouping problem calls for a set of groups with minimal cardinality. This paper considers three variants of the job grouping problem under a single formulation. A generic mathematical formulation which solves all three of them is given. The variants are abstractions of machine organizations used in present day manufacturing systems. Inspired by the new formulation of the exact solution method a joint heuristics suited for all the three problems is also constructed. Benefits of the new algorithm are its conceptual simplicity, its adaptability to different machine layouts and competitive computational efficiency.

Grouping and sequencing PCB assembly jobs with minimum feeder setups

Printed circuit boards are manufactured in automated assembly lines, where high-speed placement machines put components on the boards. These machines are frequently bottlenecks in the production. This is true especially in high-mix low-volume environments, where time consuming setup operations of the machines have to be done repeatedly. Therefore, one can improve productivity with a proper setup strategy. The most popular strategies are the so-called group setup strategy and minimum setup strategy. In this paper, we consider the machine setup problem as a combination of a job grouping problem and a minimum setup problem. We formulate this joint problem as an Integer Programming model, where the objective is to minimize the weighted sum of the number of setup occasions and the total number of component feeder changes. We also present and evaluate hybrid algorithms based on both grouping and minimum setup heuristics. The best results are achieved by a method which uses both these strategies simultaneously.

Offshoring in the Semiconductor Industry: A Historical Perspective

Semiconductor design is a frequently-cited example of the new wave of offshoring and foreign-outsourcing of service sector jobs. It is certainly a concern to U.S. design engineers themselves. In addition to the current wave of white-collar outsourcing, the industry also has a rich experience with offshoring of manufacturing activity. Semiconductor companies were among the first to invest in offshore facilities to manufacture goods for imports back to the U.S. A brief review of these earlier manufacturing experiences and their impact on the fortunes of the domestic industry and its workers can help to illuminate the current debates over offshoring in services. Because meaningful data about the impact of the offshoring of chip design (and even manufacturing) are limited, we rely on a more qualitative analysis for our key points. We have conducted dozens of interviews with engineers and managers at numerous semiconductor and related companies in the United States, Asia, and Europe over the past six years. Our research also incorporates the rich store of publicly available information in trade journals and company reports. This paper describes the two previous stages of offshoring semiconductor assembly jobs and of outsourcing semiconductor manufacturing and the impact they had on the U.S. semiconductor industry. We argue that the initial concern about losing domestic jobs in both stages turned out to be unfounded as the industry used the situation to its competitive advantage by becoming cost competitive (assembly stage) and by developing the fabless sector (manufacturing stage). We then analyze the on-going stage of offshoring design jobs, and compare this stage to the two that came before in order to explore the possible impact on domestic jobs and the U.S. semiconductor industry. We begin in section one with a brief description of the stages of semiconductor production and our analytical framework. Section two looks at the offshoring of assembly jobs, and section three analyzes the foreign outsourcing of manufacturing. Section four explores the offshoring of design jobs, and concludes with a discussion of what this means for the U.S.

A PRACTICAL FRAMEWORK TO EVALUATE AND SELECT ROBOTS FOR ASSEMBLY OPERATIONS

In robot assembly operations, the assembly cycle time is not linearly proportional to the maximum speed of the robot. Therefore, if the decision-maker wants to select and evaluate robots with respect to a specific assembly work, it is necessary to use the assembly cycle time to replace the maximum speed as an attribute in the evaluation process. This paper presents a methodology that uses assembly cycle time as an evaluation attribute instead of using robots' maximum speed. The resulting robot ranking is more realistic because the evaluation process considers the assembly jobs under consideration. Three computational examples are presented to support this conclusion.

Grouping PCB Assembly Jobs with Feeders of Several Types

A variant of the classical job grouping problem (JGP) in printed circuit board (PCB) assembly is considered. Studies on JGPs have assumed a single feeder from which the components are retrieved and then placed on the PCB. Recent advances in technology have made it possible to use several different kinds (types) of feeders at the same time. In a JGP, the aim is to group the PCBs so that the cardinality of the grouping is minimal and each group can be processed without rearranging the contents of the feeder. In the job grouping problem with several feeder types (JGP-T) the goal is the same but instead of one linear feeder we have several feeders and each component is associated with a given feeder type which restricts its placement. We give a mathematical formulation for the JGP-T and show that it is hard to solve to optimality for problems of practical size. The connections of JGP-T to known problems are discussed. We also propose several efficient heuristics and compare their results against optimal solutions.

A STUDY ON SUBJECTIVE SYMPTOMS AND OCCUPATIONAL CHARACTERSITICS OF WORK-RELATED MUSCULOSKELETAL DISORDERS

Work related musculoskeletal disorders become a hot issue in Korea since many workers reported the musculoskeletal disorder problems. The objective of this paper is to find whether workers' subjective symptoms are closely related to occupational characteristics and mu sculoskeletal stress evaluated by ergonomic techniques. Workers in an electronics companies were surveyed using a questionnaire survey form. Their work was also analyzed using ergonomic techniques. Four types of jobs, manual handling jobs, inspection jobs, assembly jobs and VDT jobs were used. It was found that 22.8% of workers reported subjective symptoms. Workers in manual handling jobs showed the most subjective symptoms ration (34.7%). It was also found that lower back was the most painful body region.. Work duration and control possibility of work speed showed significant high odd ratios. It was also found that pain reported was well correlated with ergonomic evaluation of jobs.

Why electronics in China-a business perspective

Since China opened up in the late 70s and the early 80s, the low labor cost of Chinese workers have attracted many electronics companies from around the world to set up their factories there or to sub-contract their products to Chinese manufacturers. This has earned China the nickname, "the World's Factory". One can find many products around the world wearing the "Made in China" label. Initially, Chinese industry only took on product assembly and simple development jobs. Consumer items such as radios, calculators, and electronic toys were typical of "Made in China" products at that time. Most of the research and design activities were conducted elsewhere. Most components used in assembly were pre-made and shipped to China. Only simple components were sourced locally. At that time, most of the products manufactured by foreign enterprises were exported. The Chinese market was protected by high tax rates and very few Chinese could afford foreign-made products. This trend, however, has changed fundamentally in the last ten years. The Chinese economy has improved dramatically, experiencing double-digit growth every year. The standard of living for Chinese citizens in the major cities and the surrounding areas has improved substantially. This rise in income has opened up a huge consumer market. Foreign investment in the Chinese market is increasing. Many multinational companies have moved their critical component manufacturing sites to China. More and more international companies have set up major research and sales center in this high-potential market. Having entered the WTO, China now has become one of the most important electronics markets in the world. Its role in the electronics business has evolved from simply assembling products to research and development, component procurement, marketing and sales.

Physiological workload evaluation of screw driving tasks in automobile assembly jobs

For ergonomic intervention of manual materials handling (MMH) tasks, biomechanical, physiological, and psychophysical approaches have been studied. In the automobile assembly jobs, however, very few studies on physiological stresses have been carried out, whereas many studies have been reported in biomechanical and postural stresses. In this study, physiological workloads were evaluated during screw driving tasks in the automobile assembly line. The effects of load and work postures on heart rate, oxygen consumption and subjective ratings (5-point scale) during a screw driving task were studied using nine male subjects, with a within-subject design. Heart rate and subjective ratings of all nine subjects and oxygen consumption of five subjects were evaluated during a simulated screw driving task with varying loads (8.2 kg, 16.4 kg), leg postures (standing and squatting) and trunk postures (forward flexion, forward flexion with lateral bending and twisting). The effect of load, leg and trunk postures were found to be significant on heart rate, oxygen consumption and subjective rating. Heart rate and subjective ratings showed a high correlation for all the combined conditions. For screw driving tasks, it is recommended to redesign work methods in order to avoid squat sitting, lateral bending and twisting. Relevance to industry Automobile assembly job is one of the most labor-intensive industries and workers often perform their tasks in poor working postures repetitively due to constrained work places. This study was conducted to evaluate the physiological workload of screw driving tasks in awkward working postures, such as laterally bent and twisted trunk and squat sitting. Ergonomic guidelines for such assembly tasks were recommended based on the results of a laboratory experiment.

Maquiladoras and U.S.‐Bound Migration in Central Mexico

Over the past one and a half decades, smaller cities and nonmetropolitan areas in Mexico have attracted manufacturing plants, led by the export manufacturing sector. Maquiladoras in particular are increasingly locating their plants in such places in the “deep interior” Mexico—outside of the border states. Using 1980 and 1990 Mexican census data for 19 growth centers and 27 high‐emigration municipios (counties) in Central Mexico, this paper suggests that foreign‐owned assembly (maquiladora) jobs decentralized significantly over the 1980s, locating closer to emigrant municipios. An examination of 17 emigrant municipios in the industrialized states of Jalisco and Guanajuato found that an emigrant municipio's accessibility to maquiladora jobs, and jobs indirectly related to maquiladora growth, was positively related to its overall employment growth, which was, in turn, negatively related to its U.S. migration rate over the decade. Although the migration reduction inherent in these relationships is relatively small, it could be accelerated by U.S. and Mexican policies giving incentives for more peripheral locations of export‐oriented and other manufacturing.

Integration of assembly and fabrication for make-to-order production

The problem of make-to-order production is as follows. A number of customer-specific orders have to be assembled in a multi-project type environment. Each order is made of different assembly jobs which are interrelated by precedence constraints. To be processed, an assembly job requires in-house fabricated and out-house procured parts as well as capacity of assembly resources (assembly workers, power tools). Different customer orders need the same part types and hence the fabrication of parts has to take into account lot sizing decisions. The overall problem is how to coordinate fabrication and assembly with respect to scarce capacities in the assembly and the fabrication such that the holding- and setup-cost of the entire supply chain – fabrication–assembly – are minimized. This problem has not been treated in the literature so far. Hence, we give a mixed–integer programming model for the problem and discuss its properties. Afterwards, we propose a simple, two-level backward oriented heuristic and evaluate it on a set of benchmark instances.

Dispatching rules for scheduling in assembly jobshops - Part 2

In this part of the paper, we present the development and evaluation of dispatching rules for scheduling in jobshops manufacturing multi-level assembly jobs with the performance measures reated to tardiness. We present a new definition of 'operation due date' in the context of assembly jobs and use it in the development of dispatching rules. A simulation study is carried out to evaluate the performances of the existing and the proposed dispatching rules with respect to different measures of tardiness. We also measure their performances with respect to different measures of flowtime and staging delays. The results of the study indicate that the proposed rules perform better than the existing rules.