Effective design aspects of production system.

Simon, Michal ; Troblova, Petra

Abstract: Continuous technology development still brings new machines, technologies, equipments and working methods. A disproportion between requirements and demands can rise. On the one hand new activities and new technology require many effective demands on the other hand possibilities or abilities of a human who has to exercise or operate them are limited. A human who is overworked is a result of this fact which leads to tiredness or even to a total collapse with possible damage of human health. Proposal of necessary steps of production system can considerably reduce these problems.

Key words: Production system, Ergonomics, Dynamic model, Digital design.

1. INTRODUCTION

Most of the public notices, laws and standards restricting and conditioning of working conditions try to prevent from above mentioned problem and recommend a range of possibilities how to increase a production system efficiency without threat of employees' health.

The main aim of this paper is focusing on an approximation of suitable tools for increasing production system efficiency in that way how would they tie together by realization.

2. TIME EXPENDITURE AND TIME STUDIES

Job time expenditure can be basically determine with calculation from in advance defined values, so called time norms, or with measurement.

In first case we talk about systems of defined times, which are generally signed as movement norms and the best known is MTM system (Methods Time Measurement). A basic idea of MTM is based on piece of knowledge that with a help of a restricting number of movement elements every manual working process can be described. An analysis of an operating sequence with these defined process elements is the most detailed way during a work study. In determination of time-data MTM is gaining a unique importance because with the help of this method it is possible to determine standard times already in planning stadium. An analysis proceeding consists in lay-out of an operating sequence (e.g. assembly process) into the movement elements.

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In second case we talk about methods, which are being used for time expenditure determination with observation and measurement in the workplace and are generally known as time studies. There are well-known and exploited ways of time determination which must indeed respect a range of rules and procedures. From our experience we can confirm that these rules are very often counteracted and sometimes absolutely unrespected.

Interesting output of this first phase is a comparison of above mentioned ways of time determination in selected sector or workplace. We can determine at which level of specified movement norms are times in the company at present defined.

3. ERGONOMIC ANALYSES AND DESIGN

A prevention of limit states in production process and adaptation of technology to human restrictions is a role of ergonomics. A definition of ergonomics is as follows: Ergonomics is a science which optimises an interaction between human and other system elements and uses theory, pieces of knowledge, principles, data and methods for optimizing the comfort of a human in the environment and system efficiency (Chundela, 2005).

Technical development and centralization caused this fact that started produce technology which did not respect a human variability (human proportion, force and abilities). Just ergonomics has this credit that criticises this approach and promotes conceptually only right access, that technology must respect physical, sensual and mental human barriers.

At anthropocentric optimizing of technology we must go out from human proportions. However we cannot put up with average values but we must respect also smaller and longer figures by force of percentiles. 5% percentiles mean that 5% of population has smaller proportion than indicated value and vice versa 95% percentiles mean that 5% of population has longer proportion than indicated value.

During ergonomic research we cannot talk only about human dimensioned parameters which are shown above but we must take into account also movement, somatic and energetic parameters. From best known movement parameters there are above all Inflexion parameters (flexion, angle reducing between two parts of body), Extension (angle increase) and Rotation (rotation around person's axis).

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Somatic parameters represent above all human weight which we must know for the proper design of seats or furniture for resting. For determination of optimal weight Broc's formula was defined which indicates the limit weight. Energetic parameters extend needs to deliver to a body a necessary amount of oxygen and energy in the form of food. Organism needs energy for keeping body temperature, for organs' activity and for work. We can understand energy out as a sum of energy of basal metabolism, energy for work and energy non-related to work (for other activities).

Focusing on production process efficiency realized by human resources is the, not less important, second role of ergonomics. People often forget this fact that minimal changes in production process can bring considerable effects.

We can claim that if a human and his/her activities exist ergonomic methods--optimizing of the system: human-machine-environment and development of human personality will be there.

4. LINE BALANCING

The first two phases create input data for line balancing. It is essential to emphasize this fact that this phase does not require a realization of previous two phases but then we must appreciate that we will balance unverified and perhaps not even half correct input data.

The aim of line balancing is to co-ordinate activities in individual workplaces in that way they will minimally distinguish from line tact. We search unutilized positions, their balancing and displacement on other unutilized workplaces. It seems very convenient to use graphic tools which show a time load of individual workplaces with line tact and make possible to realize and find line behaviour by change of tact.

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5. DYNAMIC MODEL OF PRODUCTION PROCESS

All above mentioned aspects, influencing production system efficiency, in principle have an effect on system design. They are a basic unit for a total layout proposal and detailing of space demands of production, warehouse and expedition.

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We can draw material flows in a format of Sankey's diagram in a total layout of company's premises. These material flows go from their resources to final destination. We can illustrate arrows representing material flows directly to resources to a final area or with the help of manipulation aisles--in rectangular ways. It is also possible to draw volume with a width of an arrow for intangible (information) flow.

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Unfortunately most of entrepreneurial units are unaware of this fact and due to a weak management of material and information flows there can be not only difficult production control but waste of time and financial loses as well.

We should indeed not forget modern means for visualization and rationalization of company's premises which are able to represent not only premises in three-dimensional design but they are able to simulate the whole process with all production characteristics as well.

Creation of a three-dimensional static model or a production premise which fully imitates the real state goes before a realization of a dynamic model. This model is certainly viewable also in two-dimensional design where it can be evaluated to keep hygienic and security norms.

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6. CONCLUSION

Other effects are subsequently caused by a dynamic model which is able to simulate the behaviour of production process in real conditions both in normal state and by changes of characteristics of existing model. We can simulate the behaviour of production system by increasing production volume, to generate randomly rising problems and in final form to optimize a composition of production programme and organization of production process for achieving maximal productivity.

It is the way how to come closer to increase production system efficiency with respect for all aspects - human, economic, etc.

7. REFERENCES

Baumruk, M. (2006). Ergonomic simulation of company's processes, University of West Bohemia, ISBN 80-7043-438-4, Pilsen.

Chundela, L. (2005). Ergonomics, Czech Technical University, ISBN 80-01-0231-X. Prague.