PRINCIPLES OF JOB DESIGN AND ERGONOMICS
Objectives
By the end of the chapter the student should be able to:
(i) Define the term job design
(ii) Define the term ergonomics
(iii) Outline the components of work study
(iv) Explain the principles of ergonomics
Job design
There are clearly many alternative designs for any given job. For this reason, an understanding of what the job design is supposed to achieve is particularly important. As before, the five performance objectives give us a guide to what is relevant in job design decisions.
1. Quality: The ability of staff to produce high-quality products and services can be affected by job design. This includes avoiding errors in the short term, but also includes designing jobs which encourage staff to improve the job itself in such a way as to make errors less likely.
2. Speed: Sometimes speed of response is the dominant objective to be achieved in job design. For example, the way in which the jobs of emergency service personnel are organised (the range of tasks for which they are trained, the sequence of activities in their approved procedures, the autonomy which they have to decide on appropriate action, and so on) will go a long way to determine their ability to respond promptly to emergencies and perhaps save lives.
3. Dependability: Dependable supply of goods and services is usually influenced, in some way, by job design. For example, in the postal services‟ working arrangements, multi-skilling, accurate use of sorting equipment through good staff-machine interface design, and the „design‟ of postal staff‟s clothing, can all aid dependable delivery of letters and parcels.
4. Flexibility: Job design can affect the ability of the operation to change the nature of its activities.
New product or service flexibility, mix flexibility, volume flexibility and delivery flexibility are all dependent to some extent on job design. (See Chapter 2 for a full description of these different types of flexibility). For example, staff who have been trained in several tasks
(multi-skilling) may find it easier to cope with a wide variety of models and new product or service introductions.
5. Cost: All the elements of job design described above will have an effect on the productivity, and therefore the cost, of the job. Productivity in this context means the ratio of output to labour input: for example, the number of customers served per hour or the number of products made per worker.
In addition, job design will influence two other particularly important objectives.
6. Health and safety: Whatever else a job design achieves, it must not endanger the well-being of the person who does the job, other staff of the operation, the customers who might be present in the operation, or those who use any products made by the operation.
7. Quality of working life: The design of any job should take into account its effect on job security, intrinsic interest, variety, opportunities for development, stress level and attitude of the person performing the job.
Behavioural approaches to job design
The title „behavioural‟ approaches in clumsy but reasonably descriptive. This approach is the first so far to take the feelings and motivation of individual members of staff into account. Now the ideas of job rotation, job enlargement and job enrichment are well established in job design practice. Nevertheless it is important to understand that this approach still keeps the responsibility for designing jobs with operations management (or personnel management, or human resource management, etc.). It does not pass any responsibility or power to the people doing the jobs. In that sense it is not fundamentally different from earlier approaches to job design. Its motivation and objectives may be different but its practice is still very „top-down‟. The principles of job desgn are:
(i) Empowerment: The idea of empowerment, for the first time gives some responsibility for job design to the individuals who will perform the job. But, as the chapter discusses, the extent of autonomy can vary significantly. At its most limited autonomy can merely involve asking staff for their suggestions as to how jobs should be designed. At its maximum, only the broadest and most general of objectives are set by higher management and the whole nature of the job and its organisation is left to those who perform it. In between these two extremes there are any number of levels. In that sense „empowerment‟ can mean almost anything. What many companies discovered is that empowerment „did not relieve them of the task of job design‟. It has been found to be very important to be clear in drawing the boundary between those aspects of the job which staff can directly control and those which management still reserve the right to define. So, for example, an operation might draw up a list of issues which it reserves the right to impose such as types of behaviour which are not acceptable (racist, sexist, etc.), safety practices (compulsory wearing of protective headgear etc.), timing (when the process must start and when shift changeovers occur, etc.), and so on.
However, it may also define a list of specific job issues which staff can decide for themselves, sequencing of activities, scheduling of activities, appropriate work methods, and so on.
(ii) Team-working and job design: The significance of this influence on job design is that the „unit of analysis‟ of job design changed. So, rather than automatically assume that job design involved defining the content of a job for each individual, a further variable was introduced – the team. A team is a group of individuals who, together, have a set of tasks to perform. From the point of view of the staff who form the team there may be a number of advantages in working on a team basis rather than an individual basis. The interest, motivation and fun which can be gained from working closely with colleagues can make any job more attractive. From the operations point of view several people working together can be not only more efficient and more flexible but also more creative in the way they seek solutions to continually improve their part of the operation.
(iii) Flexible working: Three types of flexible working are described in the chapter,
o skills flexibility
o time flexibility
o location flexibility.
In some ways this sequence of different types of flexibility is in order of difficulty. Skills flexibility involves individuals being able to do more than one job. This allows the operation to be more responsive as markets or other conditions change and also (arguably) makes jobs more interesting. It is not always easy to achieve skills flexibility, but at least most people are together in the operation at more or less the same time. Time flexibility, on the other hand, can present more difficulties because (by definition) not everyone will necessarily be together at the same time. Location flexibility can present even more problems, especially if individual members of staff rarely, if ever, meet up.
(iv) Job Enlargement: thi sinvolves the horizontal integration of tasks to expand the range of tasks involved in a particular job. If successfully implemented this can increase task identity, task significance and skill variety through involving the work Erin the whole work task either individually or within the context of a group. Job Rotation is a common form of job enlargement and involves a worker changing job roles with another worker on a periodic basis. If successfully implemented this can help increase task identity, skill variety and autonomy through involvement inawiderrange of work task withd iscretion about when these mix of tasks can be undertaken. However this method does not actually improve the design of the jobs and it can mean that people gravitate to the jobs thatsuit them and are not interested in initiating rotation with colleagues. At worst it can mean rotation between a number of boring jobs with no acquisition of new skills.
(v) Job Enrichment: Job enrichment involves the vertical integration of tasks and the integration of responsibility and decision making. I f successfully implemented this can increase all five of the desirable job characteristics by involving the worker in a wider range of tasks and providing responsibility for the successful
Methods Analysis
Dividing and analysing a job is called method study. he approach takes a systematic approach to reducing waste, time and effort. the approach can be analysed in a six-step procedure:
1. Select: Tasks most suitable will probably be repetitive, require extensive labour input and be critical to overall performance.
2. Record: this involves observation and documentation of the correct method of performing the selected tasks. Flow process charts are often used to represent a sequence of events graphically. they are intended to highlight unnecessary material movements and unnecessarydelay periods.
3. Examine: thisinvolves examination of the current method, looking for ways in which tasks can be eliminated, combined, rearranged and simplified.t his can be achieved by looking at the low process chartfor example and re-designing the sequence of tasksnecessaryto perform the activity.
4. Develop: Developing the best method and obtaining approval for this method. his means choosing the best alternative considered taking into account the constraints of the system such as the performance of the irm‟s equipment. he new method will require adequate documentation in order that procedures can be followed. Speciications may include tooling, operator skill level and working conditions.
5. Install: Implement the new method. Changes such as installation of new equipment and operator training will need to be undertaken.
6. Maintain: Routinely verify that the new method is being followed correctly
New methods may not be followed due to inadequate training or support. On the other hand people may ind ways to gradually improve the method over time. Learning curves can be used to analyse these efects.
Motion Study
Motion study is the study of the individual human motions that are used in a job task. The purpose of motion study is to try to ensure that the job does not include any unnecessary motion or movement by the worker and to select the sequence of motions that ensure that the job is being carried out in the most efficient manner possible. For even more detail videotapes can be used to study individual work motions in slow motion and analyse them to find improvement a technique termed micromotion analysis. The principles are generally categorised according to the efficient use of the human body efficient arrangement of the workplace and the efficient use of equipment and machinery. These principles can be summarised into general guidelines asfollows:
– Efficient Use of the Human Body
Work should be rhythmic, symmetrical and simplified. The full capabilities of the human body should be
employed.Energy should be conserved by lettingmachines performtaskswhen possible.
– Efficient Arrangement of the Workplace
Tools, materials and controls should have a defined place and be located to minimise the motions needed to get to them. The workplace should be comfortable and healthy.
– Efficientuse ofEquipment
Equipment and mechanised tools enhance worker abilities. Controls and foot-operated devices that can relieve the hand/arms of work should be maximised. Equipment should be constructed and arranged to it
worker use.
Motion study is seen as one of the fundamental aspects of scientific management and indeed it was effective in the design of repetitive, simplified jobs with the task specialisation which was a feature of the mass production system. The use of motion study has declined as there has been a movement towards greater job responsibility and a wider range of tasks within a job. However the technique is still a useful analysis tool and particularly in the service industries, can help improve process performance.
Work Measurement
The second element of work-study is work measurement which determines the length of time it will take to undertake a particular task. This is important not only to determine pay rates but also to ensure that each stage in a production line system is of an equal duration (i.e. „balanced‟) thus ensuring maximum output. Usually the method study and work measurement activities are undertaken together to develop time as well as method standards. Setting time standards in a structured manner permits the use of benchmarks against which to measure a range of variables such as cost of the product and share of work between team members. However the work measurement technique has been criticised for being misused by management in determining worker compensation. T h e time needed to perform each work element can be determined by the use of historical data, work sampling or most usually time study.
Time Study
The purpose of Time Study is through the use of statistical techniques to arrive at a standard time for performing one cycle of a repetitive job. This is arrived at by observing a task a number of times. The standard time refers to the time allowed for the job under specific circumstances, taking into account allowances for rest and relaxation. The basic steps in a time study are indicated below:
1. Establish the standard job method: It is essential that the best method of undertaking the job is determined using method study before a time study is undertaken. If a better method for the job is found then the time study analysis will need to be repeated.
2. Break down the job into elements: The job should be broken down into a number of easily measurable tasks. This will permit a more accurate calculation of standard time as varying proficiencies at different parts of the whole job can be taken into account.
3. Study the job: this has traditionally been undertaken with a stopwatch, or electronic timer, by observation ofthe task. Each time element is recorded on an observation sheet. A Video camera can be used for observation, which permits study away from the workplace, and in slow motion which permits a higher degree of accuracy of measurement.
4. Rate the worker‟s performance: As the time study is being conducted a rating of the worker‟s performance is also taken in order to achieve a true time rating for the task. Rating factors are usually between 80% and 120% of normal. This is an important but subjectiv element in the procedure and is best done if the observer isfamiliar with the job itself.
5. Compute the average time: Once a sufficient sample of job cycles have been undertaken an average is taken of the observed times called the cycle time. The sample size can be determined statistically, but is often around five to fifteen due to cost restrictions.
6. Compute the normal time: Adjust the cycle time for the efficiency and speed of the worker who was observed. the normal time is calculated by multiplying the cycle time by the performance rating factors. Normal Time (NT) = cycle time (CT) x rating factor (RF)
7. Compute the standard time: The standard time is computed by adjusting the normal time by an allowance factor to take account of unavoidable delays such as machine breakdown and rest periods. The standard time is calculated as Standard Time (ST) = Normal Time (NT) x allowance
Predetermined Motion Times
One problem with time studiesis that workers will not always co-operate with their use, especially if they know the results will be used to set wage rates. Combined with the costs of undertaking a time study, a company may use historical data in the form of time filesto construct a new standard job time from previous job element .this has the disadvantage however of the reliability and applicability of old data. Another method for calculating standard times without a time study isto use predetermined motion time system (PMTS) which provides generic times for standard micromotions such as reach, move and release which are common to many jobs. The standard item for the job is then constructed by breaking down the job into micromotions that can then be assigned a time from the motion time database. The standard time for the job is the sum of these micromotion times. Factors such as load weight for move operations are included in the time motion database.
Advantages of the predetermined motion times
(i) standard times can be developed for jobs before they are introduced to the workplace without causing disruption and needing worker compliance.
(ii) performance ratings are factored in to the motion times and so the subjective part of the study is eliminated.
(iii) The timings should also be much more consistent than historical data for instance.
Disadvantages of the predetermined motion times
(ii) the fact that these times ignore the context of the job in which they are undertaken
(iii) The timings are provided for the micromotion in isolation and not part of a range of movement.
(iv) The sample is from a broad range of workers in different industries with different skill levels, which may lead to an unrepresentative time.
(v) Also the timings are only available for simple repetitious work which is becoming less
common in industry.
Work Sampling
Work Sampling i suseful for analysing the increasing proportio nof non-repetitive tasks that are perform edinmost jobs.It is a method for determining the proportion of time a worker or machine spends on various activities and as such can be very useful in job redesign and estimating levels of worker output. the basic stepsin work sampling are indicated below:
1. Define the job activities: All possible activities must be categorised for a particular job. e.g. “worker idle” and “worker busy” states could be used to define all possible activities.
2. Determine the number of observations in the work sample: The accuracy of the proportion of time the worker is in a particular state is determined by the observation sample size. Assuming the sample is approximately normally
distributed the sample size can be estimated using the following formula.
n = (z/e)2 * p(1 – p)
where
n = sample size
z = number of standard deviation from the mean for the desired level of confidence e = the degree of allowable error in the sample estimate
p = the estimated proportion of time spent on a work activity
The accuracy of the estimated proportion p is usually expressed in terms of an allowable degree of error e (e.g. for a 2% degree of error, e = 0.02). The degree of confidence would normally be 95% (giving a z value of 1.96) or 99% (giving a z value of 2.58).
3. Determine the length of the sampling period: There must be sufficient time in order for a random sample of the number of observations given by the equation in 2 to be collected. A random number generate can be used to generate the time between observations in order to achieve a random sample.
4. Conduct the work sampling study and record the observations: Calculate the sample and calculate the proportion (p) by dividing the number of observations for a particular activity by the total number of observations.
5.Periodically re-compute the sample size required: It may be that the actual proportion for an activity is different from the
proportion used to calculate the sample size in step2. Therefore assampling progresses it is useful to re-compute the sample size based on the proportions actually observed.
Ergonomics
Ergonomics can be defined simply as the study of work. More specifically, ergonomics is the science of designing the job to fit the worker, rather than physically forcing the worker‟s body to fit the job.
Adapting tasks, work stations, tools, and equipment to fit the worker can help reduce physical stress on a worker‟s body and eliminate many potentially serious, disabling work- related musculoskeletal disorders (MSDs). Ergonomics draws on a number of scientific disciplines, including physiology, biomechanics, psychology, anthropometry, industrial hygiene, and kinesiology.
The Impact Of Ergonomics On Workplace Design
The goal of Ergonomics is to provide maximum productivity with minimal cost; in this context cost is expressed as the physiological or health cost to the worker. In a workplace setting there are seldom a large number of tasks that exceed the capabilities of most of the work force. There may be jobs that will include a specific task that requires extended reaches or overhead work that cannot be sustained
for long periods, by using Ergonomic principles to design these tasks; more people should be able to perform the job without the risk of injury.
Matching the requirements of a job with the capabilities of the worker is the approach to be adopted in order to reduce the risks of musculoskeletal injuries resulting from handling materials manually. Proactive Ergonomics emphasises the prevention of work related musculoskeletal disorders through recognising, anticipating and reducing risk factors in the planning stages of new systems of work or
workplaces. In effect, to design operations that ensures proper selection and use of tools, job methods, workstation layouts and materials that impose no undue stress and strain on the worker. Additional costs are incurred in redesigning or modifying work processes therefore it is more cost effective to
reduce risk factors at the design stage. A proactive approach to Ergonomics will ensure that:
• Designers will receive training in ergonomics and have appropriate information and guidelines regarding risk reduction
• Decision-makers planning new work processes should have knowledge of Ergonomics principles that contribute to the reduction or elimination of risk.
• Design strategies emphasise fitting job demands to the capabilities and limitations of workers. For example, for tasks requiring heavy materials handling, use of mechanical assist devices to reduce the need for manual handling would be designed into the process
• Other aspects of design should be considered including load design, layout of the workplace to allow for ease of access when using mechanical aids and eliminating unnecessary lifting activities.
Responsibilities of managers in ergonomics
i. Implementing and maintaining ergonomic principles
ii. Ensuring that employees are properly trained in ergonomic principles
iii. Ensuring that employees follow safe ergonomic practices
iv. Actively practicing and developing positive attitudes towards ergonomic issues
v. Ensuring that employees use the ergonomic equipment provided
vi. Considering workplace layout, ergonomics and individual needs when allocating tasks to people in your area
Responsibilities of employees in ergonomics
i. Complying with ergonomic safety instructions of their organisation
ii. Not putting themselves or other at risk by their actions or omissions
iii. Making proper use of ergonomic equipment provided
iv. Using training received in applying ergonomic principles to their tasks
v. Reporting potential ergonomic hazards and problem to their Area OHS Supervisors
General principles of ergonomics
i. Correct, neutral posture: Maintain Postures where the body is aligned and balanced, while sitting or standing. The head is kept upright and is not turned to either side more than about 30 degrees or tilted forward or backward more than about 15 degrees. When the worker is
standing, the torso is not bent more than 10 to 20 degrees from the vertical position and the natural curves of the spine are maintained. The pelvis and shoulders should face straight ahead to avoid twisting the torso. The shoulders are relaxed and knees slightly bent. The arms hang normally at the side, with elbows close to the body. The elbows are not bent more than about 90 degrees and the palms face in toward each other and the center line of the body. The wrists are in line with the forearms and are not bent sideways, forward (towards the palm), or backward (towards the back of the hand.) When the worker is seated, the buttocks and feet are
firmly supported.
ii. Cleanliness and orderliness: Establishing a strong housekeeping program will keep the work
place tidy and reduce the risk of tripping over cords and debris. It also extends the life of tools
and equipment, and results in increased productivity.
iii. Lifting: Lifting properly is important. While there are some general lifting guidelines, a different approach may be needed for each load to be lifted. Sometimes it is appropriate to lift with the legs, and other times the back should be used to lift. These techniques depend on the size and shape of the load, and the frequency of lifting that is required.
iv. Planning: Planning should be done with ergonomics in mind. Items to be planned include determining routes between staging areas and work spaces, scheduling for members of other trades, and knowing what services and utilities will be provided.
v. Power zone: lifting should be done with the power zone. The power zone for lifting is close to
the body, between mid-thigh and mid-chest height. This zone is where arms and back can lift the most with the least amount of effort.
vi. Proper handholds: Proper handholds make lifting easier and reduce the risk of injury.
Handholds should be made large enough to accommodate larger hands and should not dig into fingers and palms.
vii. Pulling vs. Pushing: Pushing is generally preferable to pulling. Pushing allows the employee to use large muscle groups and apply more force to the load. Pulling carries a greater risk of strain and injury.
viii. Staging: Staging is an important step in any electrical project. Proper staging includes placing materials as close as possible to work spaces, and storing materials at ideal heights so employees can utilize the power zone to take materials from storage.
ix. Task Rotation: Many stressors cannot be engineered out of a task, short of complete automation. Rotation of assignments can be an effective means of limiting the amount of time employees are exposed to these stressors. This will often reduce the chance of injury, because the risk of injury is proportional to the amount of time one is exposed to a stressor.
Review questions
(1) Distinguish between work sampling and work measurement
(2) Outline five principles of ergonomics
(3) Explain the steps involved in time study
(4) Highlight the factors to be considered in effective job design
(5) Explain the concept of methods analysis
References
Slack, N. and Lewis, M. (2011) Operations Strategy, 3rd edn, Pearson Education Limited, Harlow.
Vonderembse,M.A. and White,G.P.(2004)Core Concepts of Operations Management, John Wileyand Son sLtd.,Chichester.
Hayes,R.H. and Wheelwright, S.C. (1984) Restoring our Competitive Edge,John
Wiley & Sons Ltd.
Hill, T 2005, Operations Management, 2nd edn, Palgrave Macmillan, Basingstoke.
Ohno, T. 1988 Toyota Production System: Beyond Large-Scale Production, Productivity Press
