Ergonomic Challenges in Conventional and Advanced Apparel Manufacturing
Final Report (Phases I through V)
Research Sponsored by:
U.S. Defense Logistics Agency
Michael J. Kelly, Ph.D.,Technical Co-director
Daniel J. Ortiz, Project Director and Technical Co-director
Theodore K. Courtney
Dennis J. Folds, Ph.D.
Jeffery M. Gerth
Georgia Tech Project A-8311
Georgia Institute of Technology
Georgia Tech Research Institute
Environmental Science and Technology Laboratory
Electronic Systems Laboratory
Apparel manufacturing is a labor-intensive, assembly line process requiring significant amounts of
repetitive, skilled manipulation. A survey of three typical plants in the southeastern United States
identified relatively high frequencies of musculoskeletal discomfort among the sewing operators.
Poorly designed and maladjusted workstations contributed to these reported problems.
Subsequent research found that ergonomic interventions including redesign and proper adjustment
of workstations, use of ergonomically designed seating, and training in low-risk methods and
postures substantially reduced these complaints. Other innovations in equipment, job, and
organizational design, including adjustable workstations, automation, and modular manufacturing,
were also explored. While many of these technologies have potential to improve comfort, safety
and efficiency, new ergonomics issues will appear with their introduction. A textbook and
videotape to provide manufacturing supervisors instruction in identifying and addressing the most
common ergonomic problems in the workplace were developed and are being distributed.
Enclosed in this document is a summary of the five phases or tasks of this endeavor. The
appendices contain the detailed reports of Phases I, II, III, and V. Also, a copy of the training
handbook and video (Phase IV) is contained in the appendices. Top of the page
The United States apparel manufacturing industry is facing difficult challenges. Apparel
manufacturing is a labor-intensive, rather than capital-intensive, endeavor. Because it is possible
to start up a factory for a few hundred dollars per employee, it is an ideal industry for developing
nations. A ready pool of inexpensive labor in the Pacific Rim and Latin American regions provides
strong competition for North American manufacturers. In addition, the industry is experiencing a
severe shortage of entry-level sewing workers as the population ages and competition increases for
young, relatively unskilled personnel. While some of these challenges might be met by
innovations in equipment and manufacturing methods, many existing plants are financially unable
to invest in new technology.
A high turnover rate (well over 100% each year in many plants) contributes to escalating costs.
Months of on-the-job training are needed by novice operators to learn the complex perceptual
motor skills of their trade. On a typical job, novice operators require 12 - 16 weeks of training and
practice before their performance reaches established production standards. On especially difficult
jobs, as long as 26 weeks may be needed. For most workers, learning curves do not reach
asymptote until after one to two years on the job.
Conventional apparel manufacturing is a hand-intensive process as operators rapidly obtain and
position parts, guide them through the machine, and dispose of them (Kelly, Ortiz, Folds and
Courtney, 1990). As awareness of repetitive motion trauma disorders grows, the industry is
experiencing a dramatic increase in reports of upper-extremity injuries and the resulting medical
and disability payments. Fines imposed by regulatory agencies for allowing conditions conducive
to repetitive motion injuries are expected to add substantially to the already high costs.
A few previous studies have examined ergonomic aspects of the apparel manufacturing industry in
the United States and in Europe (e.g., Punnett and Keyserling, 1987; Vihma, Nurminen and
Mutanen, 1982). It was desired, however, to broaden the research into an integrated study of
ergonomic problems and their potential solutions, covering both conventional and advanced
manufacturing, and to disseminate the findings to the industry.
The goals of the research program were to (1) identify and document ergonomic-related problems
in the apparel manufacturing workplace, (2) test low cost interventions that would address these
problems, (3) identify and explore higher-technology solutions that are beginning to enter the
environment, and (4) develop a self-study course in ergonomics specifically designed for apparel
manufacturing supervisors. Top of the page
During the first phase of this program, site visits were conducted at three typical apparel
manufacturing plants in the southeastern United States. The primary product line for all three
plants was trousers. Plant A employed approximately 500 cutting and sewing operators and was
considered to be an innovator in the introduction of new technology; Plant B employed
approximately 50 operators and would accept new technology after its was thoroughly proven to
be of benefit; Plant C employed approximately 120 operators and was considered financially
incapable of adopting significant amounts of new technology. These plants provided a
representative cross-section of company sizes and opportunities for automation. (Within months
after completion of the survey, Plant B ceased operation after over fifty years in business.)
On a preliminary visit to each plant, management, engineers and floor supervisors were
interviewed and the plant was toured in order to develop an overall impression of the ergonomic
environment and potential problem areas. During these visits, specific target jobs were identified
in each plant for extra scrutiny. These were jobs having indications of ergonomic problems
including excessive turnover, absenteeism, physical complaints, or unusually long training
periods. These jobs were singled out for later video analyses and detailed workstation
measurements. Each of the three plants identified between four and six target jobs. Because of
differences in product, procedures, and nomenclature between the plants, there was little agreement
on the problem jobs.
During a subsequent series of visits, confidential interviews were conducted with 132 volunteer
operators representing the target jobs and other jobs in the plants. These interviews covered (1)
demographic factors, (2) musculoskeletal discomfort or injuries, (3) characteristics of the work
environment, (4) characteristics of the workstation, chair, and job, and (5) training.
Environmental measures of illumination, temperature, and noise were taken at sample workstations
throughout the three plants. Detailed anthropometric measurements were taken of the 132 (123
female and 9 male) cutting and sewing operators. Measurements used a GPM Model 101
anthropometer and a GPM Model 106 spreading caliper. All measures were taken with shoes
removed. Subjects were measured wearing their own working clothing, typically a lightweight
summer type clothing such as shorts, t-shirts or cotton skirts. For standing measures, subjects
stood erect, facing forward. For sitting measures, subjects sat erect on a firm, flat surface.
Operators were measured on each of ten dimensions considered to be most closely related to the
desired workstation dimensions.
Results and Discussion
Anthropometric Data Existing anthropometric databases often are not valid for specific populations
of workers (Casey, 1989). This may be especially true where job characteristics self-select for
certain physical characteristics in the worker. Smith, Smith and McLaughlin (1982) found that a
sample of female textile workers, for example, was substantially taller and heavier than the
population norm, probably due to the reaching and lifting requirements of the specific job. It was
desired to identify (or rule out) any such gross deviation from population norms among sewing
operators. The population of male operators was considered to be too small to provide meaningful
data and these measures are not included in the study.
It is apparent from comparing these data that female apparel workers do not deviate in any
substantial degree from the dimensions of all female workers as summarized on three other
published data bases. The sample of apparel workers may be slightly heavier (as suggested by the
larger thigh clearance measurement) but none of the other nine measures varied appreciably from
the other published norms. This conclusion, however, may not be valid for every plant. Some
plants now employ substantial numbers of sewing operators of Asian/American ancestry and have
reported difficulty in adjusting workstations to meet the needs of these typically smaller statured
workers. Few of these workers were in the population represented in the current study.
Musculoskeletal discomfort. Another major goal of the program was to document patterns of
musculoskeletal injury or discomfort experienced by the sewing operators and to begin relating
them to job and workplace elements that might have contributed to them. During the interviews,
the sewing operators rated the frequency with which they experienced muscle or joint pain in each
of 16 areas of their bodies.
Approximately half of all workers reported that they at least sometimes experience pain in their
upper back (52%), neck (49%), and right hand (48%). This prevalence of neck, shoulder, and
back discomfort is consistent with results of similar surveys on apparel workers in the northeastern
United States (Punnett, Robins, Wegman, and Keyserling, 1985) and in Finland (Vihma,
Nurminen, and Mutanen, 1982).
The data are also comparable to those we found in a separate study in which a sample (n=12) of
seated sewing operators rated their comfort levels at four different points during the day (Courtney,
Kelly, Folds, and Ortiz, 1990). Discomfort tended to increase throughout the day and by late
afternoon 10 of the 12 were reporting some degree of discomfort in their upper backs, 6 of the 12
were reporting discomfort in their right hands, and 3 of the 12 were reporting discomfort in their
The working posture. Much of the reported discomfort in the back and neck can be attributed to
the working posture of the seated operators. In response to job and workstation characteristics,
operators typically adopted a hunched working posture. Analyses of videotape records made of
thirty subjects in the target jobs indicated that 40 percent stooped forward (i.e., torso flexion) at
least 20 degrees throughout the machine cycle. Sixty percent tilted their heads more than 20
degrees throughout the cycle. Several workers stated that this posture is necessary to obtain
maximum production and wages. Such postures have been cited as a factor in muscle fatigue, and
discomfort (Grandjean, 1982). The tendency of operators to work in this hunched posture can be
attributed to at least three factors, the visual demands of the work, the geometry of the workstation,
and inadequate seating.
Illumination. Most sewing operations are visually demanding, requiring the precise stitching of
thread into a fabric with which there is little or no visual contrast. Overall, 36 percent of operators
stated that illumination was insufficient, requiring them to lean toward the point of operation (POO)
in order to see their work. To evaluate this complaint, we measured the average illumination at the
POO (consisting of general illumination plus supplementary workstation luminaries) for a sample
of 396 workstations. The mean value, 168 foot candles (fc), was less than 60 percent of the
Illuminating Engineering Society of North America (IESNA) recommended value of 300 fc for
visually intensive tasks with low contrast.
Workstation geometry. The tendency of operators to work in the hunched posture also suggested a
potential conflict between workstation geometry and operator dimension. Analyses indicated that
the machine treadle typically was located too close (mean=15 cm) to the proximal edge of the work
surface. Most commonly, operators responded by positioning the chair away from the work
surface in order to allow a knee angle of 110 degrees or greater. From this position, the mean
distance from the back of the chair to the point of operation (POO) was only 3 cm less than the arm
length of the 50th percentile operator. To compensate for these workstation problems, operators
leaned forward to maintain adequate visual and manual access to the POO.
Another factor limiting operator access to the workstation was the location of various obstructions
(motors, pneumatic equipment, and machine guards) beneath the work surface. While typical
recommended knee room averages about 46 cm, (Eastman Kodak Company, 1983) the presence of
these obstructions, in some cases, limited available space to less than 26 cm.
Seating. The vast majority of operations were performed in a seated position. Seating encountered
in the sewing environment typically consisted of straight-backed wooden or metal chairs. The
provided chairs lacked any cushion for reducing compression and fatigue, lacked adjustable
backrests, and often were of improper height. Most operators (91%) customized their chairs with
homemade cushions on the pan and backrest in order to adjust the height and increase pliancy.
Most cushion adjustments increased seat height by 3-6 cm when compressed.
Repetitive Manipulation. One primary risk factor for the development of repeated trauma disorders
is the frequency with which motions are repeated. On the basis of observation and interviews with
an experienced methods engineer, the sewing jobs were classified as requiring high, medium, or
low amounts of repetitive manual manipulation. While the classification was somewhat subjective,
it was closely related to the frequency of changes in hand and wrist posture. High degrees of
manual manipulation were associated with higher levels of physical discomfort almost throughout
the body. Greatest discomfort levels were concentrated in the neck, upper and middle back, right
shoulder, and hands. Seventy-three percent of the high manipulation workers reported pain in
their right hands, the highest discomfort frequency identified in the analyses. This is consistent
with the findings of Vihma, et al. (1982) of a significant relationship between hand pain and
In addition, as many as 100% of operators on certain high manipulation jobs (e.g., top-stitching)
reported symptoms that are often associated with repetitive trauma disorders, including nocturnal
numbness in the hands and fingers. In the overall population of sewing operators interviewed, the
incidence of such reported symptoms was approximately 30%, a somewhat higher incidence than
has been previously reported (e.g., Punnett and Keyserling, 1987). Our higher frequency can
partially be attributed to the interview sample that was purposely weighted to emphasize problem
The cycle time of the 14 target jobs ranged from 10 to 109 seconds with most in the 20 to 40
second range, very similar to the cycle times recorded by Punnett, et al. (1987). There were an
average of 29 left hand and 25 right hand posture changes per cycle. The most frequent hand and
wrist postures included pinch (lateral and pulp), ulnar deviation, flat press, extension, and flexion,
Relatively low cost solutions are available that can address much of the musculoskeletal discomfort
reported by the operators in the initial survey. Badly designed and adjusted workstations can be
properly adjusted for the operators; ergonomically-designed seating can replace the hard,
Training. Initial training of sewing operators was performed on the job in all three of the plants
examined. One plant had a specialized training department responsible for initial and continuing
training; the other two plants provided training by the floor supervisors. Training periods varied
from a few days to as many as six months. None of the plants provided specialized instruction in
effective training techniques for their supervisors or training staff.
There was evidence that improvements in operator training are being made, especially for newly
hired workers. Higher percentages of younger operators reported receiving job-methods training
using visual aids or videotape, training on posture, training on lifting, and training on other safety
issues. As suggested by the table, videotape is only infrequently used during initial training but is
more commonly used for cross-training the more experienced operators. Training feedback was,
at best, inconsistent. After the initial hour or so of intensive training, return visits by the
trainer/supervisor were sporadic. One plant posted a daily learning curve chart on the novices'
workstations but even this degree of performance feedback was unusual. Top of the page
While most sewing operators continue to sit on hard, unadjustable seats during the workday,
ergonomically designed chairs for the sewing operator are now available (Yu and Keyserling,
1989). These chairs have easily adjustable seat height, seat pans, and backrests. They are
adequately padded and promote a lordotic seated posture. Little formal effort had been made to
validate the effectiveness of these chairs in the manufacturing environment. The goal of this study
was to provide a field evaluation of the effects of workstation adjustments, posture training, and
ergonomically designed seating on the comfort, posture, and production efficiency of sewing
Two studies were conducted on the effects of ergonomically designed chairs on posture, comfort,
and production efficiency in cut-and-sew manufacturing plants. In the first study, ergonomically
designed chairs were tested on the sewing floor of a trouser manufacturing plant (Courtney, et al.,
1990). Twelve sewing operators took part in the study. Before initiation of testing, all operators
rated their levels of musculoskeletal discomfort in fifteen areas of their bodies at approximately
two-hour intervals during the work day to provide baseline comfort/discomfort levels. The
subjects were videotaped from the side as they worked so that measures of postural angles could
The operators were divided into two groups of six each. The six operators in the control group
then received instruction in proper working posture and were individually given recommendations
on adjusting their workstations and chairs to ergonomically appropriate configurations. The six
subjects in the experimental group received the same posture training and workstation
recommendations; in addition, they were supplied with the ergonomically designed chairs and
carefully trained in their use.
After a period of approximately five weeks, the sequence of discomfort surveys and videotaping
A subsequent study tested ten sewing operators in two different plants (Peck, 1990). One plant
produced active-wear such as sweatshirts; the second produced medical supplies. This study used
the same discomfort survey and videotape posture analysis but employed a before-and-after
experimental design rather than matched groups.
Results and Discussion
The changes were remarkable. In the first study, the experimental group showed substantial
improvements in both posture and frequency of musculoskeletal discomfort. The mean
improvement in back angle was 8.3 degrees with five of the six subjects showing improvement.
Reported musculoskeletal pain decreased by 90.3 percent. The control group showed a mean 2.5
degree improvement in back posture with three of the six subjects showing improvement.
Reported musculoskeletal discomfort decreased by 53.6 percent. No change in production was
seen, however, for either group.
In the subsequent seating study, the changes in posture were not as pronounced as those found
during the first study. The subjects, however, reported an almost identical 90% reduction in
discomfort frequency when using the ergonomically designed chairs. A statistically significant
increase in production was experienced by subjects in one of the two plants after introduction of
the ergonomic chairs. Given the choice, 15 of the 16 operators who tested the ergonomic chairs
during the two studies elected to keep them after the conclusion of the studies.
In field studies of this kind, the experimenter must be mindful of potential contamination of the
data by the Hawthorne effect, by the demand characteristics of the study, or by other aspects of the
situation that are not under strict control. Traditionally, the Hawthorne effect is most evident in
increased production on operator-paced jobs. To explore the possibility of such an effect, we
compared production data during the five weeks of the study with historical and post-study data
from the same operators. Only one of the three test sites experienced any change in production
efficiency that could not be directly attributed to identified outside factors. We attribute the lack of
evidence for a Hawthorne effect to at least two factors. First, great care was taken to make the
experimental procedures as invisible as possible to the operators. Second, the plants in which the
studies took place were relatively innovative and small experiments like this were a typical part of
the operators' jobs. Top of the page
Some plants, especially the larger ones, are beginning to recognize and address ergonomic and
workstation problems through the introduction of relatively advanced manufacturing technologies.
These include such approaches as job automation, automated materials handling, ergonomically
improved workstations, and the introduction of modular manufacturing cells. Many of these
approaches bring with them new or revisited problems and challenges for the ergonomist. During
this phase of the program, we explored and documented emerging technologies in the apparel
manufacturing industry through experimentation, interviews with equipment manufacturers,
apparel manufacturers, and manufacturing personnel.
Automated Materials Handling
In conventional manufacturing operations, boxes of parts and bundles of approximately 40
unfinished garments are carried, dragged, or wheeled on specially designed carts between
workstations. Materials movement is done by the operators, themselves, or by designated "bundle
boys." Automation of this materials handling process has received a significant amount of
attention, perhaps to the detriment of other automation opportunities (Weissbach, 1986). Various
vendors are now introducing automated equipment that is designed to make this materials handling
A unit production system (UPS), a computer-controlled overhead conveyor, may be used to move
hangers of parts or partially assembled garments from one workstation to the next. Rather than
large bundles of parts, each hanger typically carries the components of a single garment or a small
number of garments.
In one plant that was surveyed, 100 workstations were connected by a typical automated, ceiling
mounted UPS line that carried individual unfinished garments on hangers. A central computer
tracked each garment as the bar coded hanger passed by a series of bar code readers on the
conveyor line. The garment was automatically moved to the next operation and routed to one of
the sewing operators according to the UPS's preprogrammed logic. The garment typically was
delivered to the appropriate workstation in a queue near the operator's left shoulder.
Some operators complained about a perceived increase in the noise level and reported temporary
auditory threshold shifts during and after the workday. The noise level peaks at the operators'
ears, largely produced by impacts between the heavy plastic hangers as they dropped into the
queue for the workstation, was measured at between 95 dB and 97 dB at a majority of the
workstations. These peaks, occurring every few seconds (depending on the length of the
operation cycle at the workstation), were superimposed over a continuous noise level of 82 - 88
The UPS reduced horizontal reach requirements and all but eliminated heavy lifting by the
operators. It resulted, however, in increased vertical reach requirements and increased wrist
pronation during acquisition of materials. Interviews on body part discomfort with a sample
(n=12) of operators on the conveyor line indicated slightly higher frequencies of hand and leg
discomfort among this sample than among their counterparts who utilized conventional materials
Operators on the UPS line expressed dissatisfaction with the "intelligence" of the automated
controller. Although the system was designed to be operator paced, faster operators reported that
they often experienced empty queues at the same time that work was still being routed to the slower
workers. Other difficulties included "ghost hangers" that had dropped their bundles somewhere
but were still being moved through the system and counted as units of production.
Perhaps the greatest problem with the UPS was its lack of flexibility and the difficulty in making
short-term changes in its logic. Slight changes in the production process, for example reassigning
a given workstation to do a different operation for a single day, or temporarily changing the work
flow for a short run of a different product could not be done economically. This UPS installation
was eventually idled and abandoned when the company changed their product line to a different
garment and determined that the UPS could not cost-effectively be altered to support the new
Many leaders in the industry believe that a solution for some of the training and ergonomic
problems lies in partial automation of selected manual manufacturing operations. Automation, for
example, can reduce the skill requirements of a complex positioning and guiding task so that
novice operators might reach acceptable levels of production within a period of days or weeks
rather than the several months currently required. Partial automation can also eliminate many high
risk hand and wrist postures and the frequency of hand movements, thereby reducing the exposure
to common repetitive trauma disorders.
There are significant technological barriers to the introduction of complete automation to the sewing
workstation. Much of the difficulty is due to the nature of the raw material, fabric. Unlike
relatively rigid materials such as metal, plastic, or ceramics, a single ply of fabric is difficult to
push or pull or to hold in position with the degree of accuracy required in the manufacturing
process. Workstation automation, therefore, must (1) concentrate on operations in which precision
is not required, (2) find techniques for making the fabric "act" rigid, and (3) use a hybrid approach
in which human operators continue to feed and guide the machines during precise tasks.
Automated cutting machines now being introduced into the industry are programmed to cut stacks
of fabric parts precisely and in a given order from a "spread" of 100 or more plies of fabric. By
creating a partial vacuum under the porous tabletop, air pressure is used to hold the thick stack of
fabric rigidly in place. Cutting of the spread is done automatically by a cutting blade, cutting at
speeds up to 2000 cm/minute, under control of the computer.
Partial automation of sewing operations can eliminate some of the risk factors for CTDs. As an
example, production of a "felled seam," the kind of double overlapped seam found on the side of
denim jeans, requires an awkward posture of wrists, hands, and fingers to hold the fabric in
position as it is guided through the sewing machine. This job generally requires over six months
of training time and it has a disproportionate incidence of hand and wrist injuries. In recent years,
a folding attachment for the sewing machine has become available that guides the fabric edges into
the appropriate double-overlapped position eliminating many of the operators' motions and
awkward hand postures. A more recent innovation, an automated felled seamer, simplifies the job
even further, allowing the operator to use nearly neutral wrist and hand postures throughout the
operation. In addition to reducing the incidence of repetitive trauma injuries, this is expected to
reduce training time by a substantial amount (Textile Clothing Technology Corporation, 1989).
Numerous ergonomists have recommended the use of tilted tabletops to reduce wrist and back
angles and to improve visibility during sewing operations. A rapidly adjustable workstation was
selected for use in testing this hypothesis. The height of the top was adjustable between 71 cm and
110 cm (28 in and 43 in). The top surface of the workstation could be tilted through angles of +15
degrees through -15 degrees. All adjustments could be made by the operator using a pair of
handles below the work surface controlling two hydraulic cylinders. In the Southern Tech AMTC,
a Pfaff 463 machine was mounted on the workstation and the operator worked from a seated
Tests of the effectiveness of different tilt angles of the work surface were conducted. The sewing
operator assigned to that workstation performed the task at worktable angles of 0 degrees, +15
degrees, and -15 degrees. Videotapes of back and wrist posture were taken as the operator worked
and the operator was interviewed at the end of the series of trials. Results indicated no significant
difference in wrist or seated postures that could be ascribed to the tabletop angle. The operator,
however, expressed a strong preference for positions in which the back of the workstation is tilted
Operator Real-Time Information System
Operators who receive near-real-time information feedback about the level of their performance
might be expected, according to behavioral principles, to improve their performance. Real-time
production management systems are reaching the work floor to track the location and flow of
particular bundles, and the status and performance of individual workstations. Terminals at each
individual workstation are connected to a central computer system. Managers and supervisors
have access to this information to aid in production management and planning. Similar data may
be available on the terminals at each workstation but it is not easily obtained and interpreted.
GTRI designed and prototyped a real-time display system that would allow the operator to
establish production goals and would provide the operator with continuous information, in bar
graph form, of progress toward meeting the established goals. A touch-screen system on the small
color monitor could be used to sign on and off, establish goals, change goals, determine total
earnings and projected earnings for the day, and perform other display-control functions. The real
time display system could be integrated with the information network on a real-time production
management system, like those currently in existence, to provide these data at selected
workstations. The system would be most cost-effective if used in conjunction with operator
training and retraining. Top of the page
Based on the results of the research in the first three phases, a 100 page manual and 30 minute
video entitled "A Stitch In Time: The Supervisor's Guide to Ergonomics" were developed as a
training package for apparel manufacturing supervisors. Written at approximately the eighth grade
comprehension level both manual and video contain 5 corresponding sections. The first is entitled
"Making the job fit the worker" and provides a working definition of ergonomics. Section two,
entitled " Work station design", focuses on the relationship between posture and the design of the
work station. Section three, "What are CTDs", is concerned with defining the major cumulative
trauma disorders and discussing the risk factors and possible solutions. Section four, "The work
environment", concentrates on the influence of noise and lighting on worker performance and
section five, "Training and retraining workers", is primarily concerned with training concepts
important to the supervisor.
User testing of the manual at an apparel plant in Georgia suggested that, overall, the manual was
written at the right level. The key feature most often noted by participating supervisors was the
strategic use of pictures to illustrate the concepts. Over 770 companies and institutions have
purchased more than 2100 copies of the training package (Appendix A contains the latest list of
companies). The success of the manual and video has been largely due to the tremendous publicity
both received in a wide variety of publications and journals (Appendix B contains the list of
publications). Top of the page
There are currently significant efforts under way to eliminate the progressive bundle assembly-line
process and to introduce the concepts of modular manufacturing cells into the apparel
manufacturing workplace. In this concept, a complete garment (or major sub-assembly) is
produced in a modular cell of, perhaps, ten operators and twenty machines. Operators are not
assigned to a single operation but may move between workstations as the flow of product requires.
Individual workstations are typically shared by two or more operators. In contrast to traditional
management practices, the team of operators in the cell is responsible for many elements of
workflow planning and management, team formation and interpersonal relations, and product
quality. Because modular cells are rapidly reconfigurable, modular manufacturing has been
promoted as an efficient way of providing a quick response to the common need for a short
production run of a particular product.
Attempts to introduce modular manufacturing have produced inconsistent results with both notable
successes and distressing failures. Anecdotal reports suggest that, after a period of adjustment,
many workers experience significantly decreased levels of musculoskeletal discomfort due to the
increased variety in movements, to improved postures at the standing workstations, and to
motivational factors. Increased morale and workgroup cohesiveness, along with substantially
reduced absenteeism, have also been seen in successful implementations.
Numerous ergonomic questions and challenges appear during the implementation of the modular
system. Many traditional workstations will need to be redesigned. Increased
adjustability/adaptability will be required for workstations that are shared by two or more
operators. Issues of job design, training, organizational design, performance assessment and
reimbursement will need to be successfully addressed.
As one example of ergonomic issues in workstation design, some implementations of modular
cells have required a switch from a primarily sitting workplace to a primarily standing workplace
because of the need for operators to move between the workstations in the module. This
necessitates redesign of machine controls since the traditional sewing machine foot treadles are not
usable from a standing position and existing standing foot controllers do not provide the necessary
level of sensitivity for precise machine control. Several designs of new foot-actuated controllers
have recently been introduced but none has proven entirely satisfactory.
In unsuccessful attempts at implementation of modular manufacturing, reduced individual
production is often attributed to the lack of specialization by operators and to less efficient material
handling techniques. Inability to effectively plan and manage production within the cell,
interpersonal problems, and dissatisfaction with new group-incentive pay schemes are also cited as
problems. Other ergonomic problems related to job, workstation, and workgroup organization are
certain to become apparent as the apparel industry's experience with modular manufacturing
Our data indicate that the overall degree of discomfort reported by standing modular operators does
not differ significantly from that reported by seated operators in progressive-bundle plants.
Standing modular operators report somewhat more foot pain (possibly related to inadequate control
devices) and somewhat less pain in other parts of the body (related to posture changes). Operators
reported that subjectively they noticed a decrease in musculoskeletal discomfort on moving from
bundle to modular processing. For this and other reasons, operators' preference favored modular
systems by a wide margin. There is nothing in the discomfort reports that would argue against
standup modular work. Substantially more work, however, needs to be done on the development
of machine controllers for standup operators. Top of the page
The apparel manufacturing industry in the United States presents significant challenges for the
ergonomist. A large percentage of plants are experiencing marginal profitability and can afford no
more than quick, band-aid solutions to their ergonomic problems. For these organizations, the
ergonomist has much to offer in terms of recommendations for workstation geometry adjustments,
improved seating, and improvements in workstation lighting and noise protection. Highly
motivated plants are able to develop inexpensive and ingenious solutions to many of the problems
that are brought to their attention.
Other, more prosperous organizations are able to experiment with introducing some one or more of
the elements of new technology described above. Ergonomically designed seating should be a top
priority, but companies often need assistance to distinguish between well designed chairs and those
that are "ergonomic" in name only. Other elements of workstation and materials handling
automation are becoming popular but managers can certainly use the services of an ergonomist to
help lead them through the kinds of pitfalls described above.
Many plants still operate under an unenlightened management philosophy that rejects the
application of ergonomics practice. Managers fear that it will "plant seeds of suspicion" in the
workforce and lead to increased malingering and frivolous workers' compensation claims. The
authors have frequently heard the opinion expressed that cumulative trauma disorders are a
contagious psychosomatic affliction spread primarily through contact with union organizers and
personal injury attorneys. It is worth noting that even in these plants the sewing operators have a
vague recognition of their ergonomic problems. They need not be told, for example, that their
chairs are uncomfortable and that their backs ache. They are aware of occupational injuries
through media reports and discussions with their coworkers.
An increasing number of apparel manufacturing plants, however, are adopting a more enlightened
attitude toward ergonomics. A few large companies have added full-time ergonomists to their
management teams; a larger number of companies are using outside consultants to help organize
and support inplant ergonomic projects.
One of the most important roles the ergonomist can play is educating the plant management, floor
supervisors, and workforce. Managers need to be aware of the importance (for both humanitarian
and cost reasons) of a continuous program of surveillance with a goal of detecting ergonomic
problems before they are translated into acute or cumulative injuries. Plant floor supervisors need
to be educated to support this surveillance program by recognizing symptoms of ergonomic
problems including maladjusted workstations, inadequate seating, inadequate illumination, and
high-risk working postures and motions, by helping to identify intervention strategies and by
training workers to do the same. Ortiz, Kelly, and Davis (1991) have prepared a workbook and
accompanying videotape specifically designed to educate the apparel plant floor supervisor in ways
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