With the application of the study of movements, study of times and process information, a study of methods is obtained that results in the development of a workstation that uses the basic principles of the economy of movements and the analysis of the operation.
The job analysis aims to determine the most effective method in the given circumstances, the designer of the tools and tools can use this analysis to imagine all the movements of the operator and adapt his design to them.
With a single time that the work is analyzed and recorded, it is possible to reproduce it at any desired moment, obtaining a faithful replica of the arrangement of tools, machines and products.
Work simplification is the application of techniques that determine the content of a defined task by fixing the time that a skilled worker invests in carrying it out according to a pre-established performance standard; With work measurement, efficiency can be increased and time standards can be provided that will serve as information to other company systems, such as costs, production scheduling, supervision, etc. Therefore, work measurement is a tool that the administration has to control work efficiency and thus be able to increase it.
Given the needs of the administration and supervision of companies, work measurement arises as a tool that, if applied by properly trained people, will give satisfactory results.
The fundamental objects of the analysis of the work are the improvement of the method, the instruction, the design of tools and the documentation.
The stages to improve the efficiency of production are as follows:
- Methods to improve work Presentation of alternative methods Economic evaluation of the proposed methods Selection of the new method Implementation of the proposed method Control of the new method and comparison of results Methodology for the design of work stations.
1. Methods to improve work
To improve the work, an analysis must be carried out that implies the use of process flow diagrams, man-machine diagram, bimanual diagram, simograms, and work station diagrams, time study.
Through the use of these diagrams, movements of the entire operation are studied and unnecessary or inappropriate movements are identified; as well as the possibility of using devices or a better arrangement of the workplace to reduce the time it takes to perform it.
In order to improve a job, it is necessary to know exactly what it consists of and, except in the case of very simple and short jobs, all the details are rarely known and by direct observation they are recorded without relying on good memory. In this record the details should be written clearly and concisely.
Do not lose sight of the fact that the record of all the facts and details of the work are done in order to analyze them and not just to obtain a history or picture of how things are being done. Therefore the record must be in such a way as to facilitate analysis; Furthermore, as the jobs that can be selected in an industry are processes or operations, there are already special forms designed according to the type of job.
For the recording of the manufacturing process, the operations process diagrams are used; the process flow path and the threads. For the registration of man-machine and group process relationships (crews); The bimanual process diagram (left hand-right hand) is used to record the operations performed by the workers.
Once all the details of the work have been recorded, the next step is to analyze them to see what actions can be taken.
In order to analyze a work in a complete way, the study of methods uses a series of questions that must be applied in every detail in order to justify the existence, the place, the order, the person and the way in which it is executed.
The mentioned questions and how to use them is as follows:
Why is every detail done? What is each detail for?
The answer to these two questions does not justify the purpose of every detail; this is comes to tell us the reason for its existence. If these questions cannot be reasonably answered, it is not necessary to continue analyzing the detail, since it is illogical to think that if its existence is not justified, the circumstances under which the detail is executed can be justified.
Assuming the why and what could be reasonably answered, the next question is Where should the detail be done? When should the detail be done? Who should do the detail?
In addition to this strictly analytical criterion, the study of methods requires that this mentality investigate causes and not effects; record the facts, not the opinions and consider the reasons and not the causes.
In order to develop a better method for executing the job, it is necessary to consider the answers obtained. The responses lead to the following actions:
Remove. If the first questions why and why could not be answered reasonably, it means that the detail under analysis is not justified and should be eliminated.
Change. The answers to the question when, where and by whom can change the circumstances of place, time and person in which the work is performed. That is, to find a more convenient place, a more suitable order or a more capable person.
Change and rearrange. If there has been a need to change some of the circumstances under which the job is performed, there will generally be a need to change some details and rearrange them to obtain a more logical sequence.
Simplify. All those details that could not be eliminated, possibly can be executed in an easier and faster way. The answer to the question how, will lead to simplify the way of execution.
2. Presentation of alternative methods
The study of methods is the systematic recording and critical examination of existing and planned ways of carrying out work, as a means of devising and applying simpler and more efficient methods to reduce costs.
The purposes of the method study are as follows:
- improve processes and procedures; improve factory, workshop and workplace layout, as well as machine and plant models; save human effort and reduce unnecessary fatigue; improve the utilization of materials, machines and labor; create better material working conditions.
Basic procedure
When examining any problem it is necessary to follow a well determined order, which can be summarized as follows:
- Define the problem Collect all the data related to it Examine the facts critically but impartially Consider possible solutions and choose one of them Apply what has been solved Keep an eye on the results
So the methodology to present alternative methods is:
- Select the job Record details of the job Analyze details Develop alternative methods Evaluate advantages and disadvantages Select method Implement method by training operators of the new method
3. Economic evaluation of the proposed methods
The most economical way to enter production is the starting rule to start producing; therefore, machines, equipment, and workstations must be as simple and economical as possible.
In addition to that the standard production time must be the minimum possible after analyzing times and movements; as this means reduction of standard production costs in terms of direct and indirect manufacturing costs.
The alternative methods proposed often consider investments, said investments must include a return on investment; cost-benefit.
The method study specialist must prepare a cost benefit analysis on each of the proposed methods. This is usually done in several stages.
A first step is to determine which costs and benefits in a very broad sense are linked to each potential change. This can often be done very quickly and provides enough information to exclude various possible changes and methods from the more detailed evaluation process.
When looking at benefits, include not only those that are easy to quantify (such as direct financial savings), but also those that can only be expressed in qualitative terms. Those benefits (for example, improvements in job satisfaction, employee morale, or work relationships) can have long-term effects on financial performance and should be included in the evaluation process.
4. Selection of the new method
Once you have several alternatives to carry out the work in an operation; An analysis is carried out that implies a comparison based basically on the cost benefit.
A series of indicators must be raised that must be answered by each method in order to make a more accurate quantitative evaluation.
The feasibility of each method must be submitted to the operator for consideration, as he provides valuable ideas due to his experience so that this method is as efficient as possible; In addition, by taking their points of view into account, he will be motivated and more easily welcome improvements.
Any improvement in the method must be justified by the savings. Which implies the reduction of work time by eliminating unnecessary movements, storage, inspections, delays, generation of rework, waste.
The investments that arise must be well justified in terms of savings thanks to them; Therefore, the time in which said investment will be recovered and the way to achieve this recovery must be analyzed.
Before installing an improvement, it is necessary to be sure that the solution is practical under the working conditions in which it will operate. In order not to forget anything, a review of the idea should be done. This review must include as fundamental parts all the economic and safety aspects, as well as other factors: product quality, quantity of product manufacture, etc.
If, once these aspects are considered, it is seen that the proposal is good and will work in practice, we must see if they will affect other departments or other people. When this happens, care must be taken to monitor all human and psychological aspects, as they are generally of greater importance and significance than the others.
5. Implementation of the proposed method
The implementation of a new working method implies conviction; first of the command immediately superior to the analyst; This is achieved by presenting a comparison of indicators such as: operating time, delays, transportation, storage, waste, performance, movements, labor cost, material cost, waste cost, production and productivity. In addition to this, an investment projection must be presented if required due to the improvements as well as the way and time in which it is intended to recover said investment; along with the reason for this recovery.
Once the appropriate method has been chosen, a dialogue with the operator should be explained, explaining why it is good for him to try the new method and that it has advantages both for his benefit and for the company.
The operator and supervisors tend to exhibit natural resistance to change; However, if their opinions have been taken into account to improve the methods, it is more likely that they are already sensitized to adopt a new method.
At first it is difficult for them and they forget, but you must work for a long time with the operator until the method is fully learned. We must not forget that any change generates crisis and this tends to discourage the operator and the supervisor; It should be remembered that efficiency will be achieved gradually, as this is indicated by the learning curve.
The interests of the individuals affected favorably or unfavorably by a modification must always be kept in mind. Therefore, it is advisable to keep people informed in advance of the changes that will affect them. Treat staff with the category and dignity that their human quality deserves. Encourage everyone to give suggestions. Give recognition for their participation to those who deserve it. Be honest in using other people's suggestions, explain why a suggested idea is impractical, and make people feel that they are part of a common effort to improve working conditions in the factory.
6. Control of the new method and comparison of results.
The control basically involves 4 stages which are:
- Standardization or definition of the method to be implemented Execution of the method by the operator Supervision of the method: This implies making revisions, observing deviations from the procedure established with its execution to see that it is done correctly, or the reasons why it does. Likewise, it is required to check that the garments have good quality and that the method does not harm the safety of the worker. Adjust: Adjustment requires taking corrective actions in the implanted method; in order to make improvements identified through supervision that allow increasing efficiency and productivity.
7. Methodology for the design of workstations
Motion and timing studies cannot be performed without a workstation layout.
This layout is a drawing of the workstation, including equipment, materials, and operator space; it must be based on the principles of the economy of movements.
Workstation Diagrams.
They are limited to the physical area of the job where the activity to be studied takes place. They study smaller movements. In them, particular cases are studied, but not general ones.
Some factors or variables change in magnitude, such as:
to. Capital investments are lower b. The changes do not involve radical technology changes c. By changing the working methods it is not necessary to change the type of flow implementing in the Company d. No investment in time is necessary for planning
In addition, the changes that are sought in the Company with decisions of large investments have repercussions in high savings in money.
In the jobs using the corresponding diagrams, it takes more time, they are more complex studies and in most cases they are of little investment, but the results in efficiency and productivity can be higher.
Finally, they are diagrams that by their nature allow the study, not only of the activity, but also of the operator who performs it.
The following information should be included in the design of a workstation:
- Workbench Arrival material (bolt, clamp, washer and nuts; packing and quantity should be considered) Outgoing material (finished product) Operator space and access to equipment Location of waste and rejects Devices and tools Scale of the drawing (A three-dimensional drawing shows much more information).
The guidelines for efficient and effective design are known as principles of the economy of motion.
Principles of the economy of movements:
- Hand movements: The hands should operate with mirror-like movements; they must start and stop simultaneously, move in opposite directions, and work at all times. To design a normal workstation, the technician will need to place all parts and tools between normal and maximum reach, trying to keep them as short as possible. One challenge is keeping your hands working at all times.Ballistic movements: Ballistic movements are created by putting a set of muscles in motion without trying to suspend them by other muscles. Example: throwing a piece into a tub or pressing the panic button on a machine. Controlled or restricted movements: They are the opposite of ballistic and require more control, especially at the end of the movement. Example: Careful placement of parts.These moves are justified when there must be safety and quality considerations. If ways are found to replace them with ballistic movements, it is possible to achieve a reduction in cost. Continuous movements: These are curved and more natural movements. When the body has to change direction, it slows down and performs two separate movements. If the direction changes less than 120 °, two movements are required. Example: Reaching inside a box of pieces that is on the table requires two movements: one to reach the edge of the box and another to insert the hand. If the box were placed at an angle, a single movement would be used.Location of parts and tools: Choose a fixed place for everything (parts and tools) and have it as close to the point of use as possible.This helps with habit formation and speeds up the learning process. If the work accessories are organized so that you know where each tool is, it can be taken without looking. The further the operator has to go to get something, the more work it will cost. Creativity is required to minimize the scope. We can put pieces on different levels. Example: Instead of placing a row of parts or tools, three rows would be better. Weighted tools can be placed on the workstation. Use of conveyor belts can be used to get parts in and out of the workstation. Free hands as much as possible: Other means of holding parts must be provided.Attachments and devices must be designed to hold parts so that operators can use both hands. Foot-operated control devices can be designed to operate the equipment so that the hands are free for work. Conveyor belts can pass parts in front of operators so they don't have to pick up or put down the base unit. Electric round tables are also used to move parts in front of an operator. The devices can be electric, pneumatic, hydraulic or manual, have any shape, as the part needs. Device design is easy if you know the part and the processes it goes through. Take advantage of gravity: Gravity is free energy that can bring parts together.If an inclined plane is placed at the bottom of the part containers, the parts Use ergonomics (operator considerations): Workers should be allowed to work at the correct height, with comfortable chairs, sufficient light and adequate space to carry out your tasks.
Movement patterns
A movement pattern is the path traveled by both hands in the process of making a part or a pair of parts (if two are made at the same time). The path of each hand should be continuous and form a complete loop. A movement pattern is also a blueprint of the working method and a bill of materials for a time standard.
The workstation layout must be completed before drawing the motion pattern. The first pattern of movements is drawn on the workstation and then redrawn on a separate page to allow analysis. For the same job, the movement pattern and the cyclograph stroke would look identical.
All work consists of elements. An item is an indivisible part of the job, generally comprising a reach, a hold, a movement, and an alignment or position.
Bibliography
- Philip E. Hicks., Introduction to Industrial Engineering, CECSA.Vaughn, RC, Introduction to Industrial Engineering, Reverte.OIT, Introduction to Labor Study 4th revised edition, Limusa Mexico year 2000. GARCIA CRIOLLO R, Labor Study. McGraw Hill 1999. MAYNAR HB Industrial Engineering McGraw Hill 1998.BARNES Ralph, Study of movements and times Aguilar 1990.NIEBEL Benjamin, Industrial Engineering, Methods of times, alpha omega 1990.KRICK EDWARD, Methods Engineering, Limusa 1996. ALVAREZ Eduardo, manual of times and movements, 1999.Roger Schroeder, Operations Administration, McGraw Hill l997.José María Elias Casas, Standard time manual, UTP Pereira l970.Trejos Carlos Ariel, Measurement of working methods, Univalle, 1980.MEYERS Fred E. Study of times and movements, for agile manufacturing, 2nd. Edition,Prentice Hall, Mexico 2000, Miller d. M., Industrial Engineering and Operations Research, Limusa.
