Unit 7 Metrod Study

UNIT 7 METROD STUDY

Structure 7.1 Introduction Object~ves 7.2 Objectives of Method Study 7.3 Procedure of Method Study 7.3.1 Select 7.3.2 Record 7.3.3 Examine 7.3.4 Develop 7.3.5 Install 7.3.6 Maintain 7.4 Micro-motion Study 7.5 Equipment Used for Micro-motion Study 7.6 Factors to be Considered while in Conducting Method Study 7 6.1 Mot~onEconomy Factors 7 6.2 Economic Factors 7.6.3 Technical Factors 7.6.4 Human Factors 7.6 5 Operational Complexity 7.6 6 Delays 7.7 Tools of Method Study 7.8 Summary 7.9 Key Words 7.10 Answers to SAQs

7.1 INTRODUCTION

Growing competition has necessitated the industrial engineers to think of improving the productivity. The financial resources being scarce, they were constrained to search the gaps in the method and these researches have resulted in tremendous improvement in the form of method studies, particularly during the period between two world wars. This has grown with its branches in the third world and the concepts are still alive due to their strengths. The history has clearly been explained in Unit 1 of the same block of this course. In this unit, the procedure of method study. its applications and merits are discussed. Though the initiative for the method study was from Taylor and his students, it was developed by many industrial engineers and industrialists. All the credits go to Frank B. Gilbreth and his wife Lillian M.Gilbreth for their invaluable work in method study. Objectives After studying this unit, you should be able to understand and define method study, conduct a method study on any given job, s identify the factors influencing method study, and apply the tools of method study successfully. Wnrk Systen~Ilesign 7.2 OBJECTIVES OF METHOD STUDY

The method study is conducted with a main focus on the following objectives : (a) To bring improvement in process or procedure. (b) To bring improvement in work place, workshop, working environment, layouts, etc. (c) To bring economy in use of human effort and thereby enhance the human efficiency and productivity. (d) To reduce unnecessary fatigue. (e) To increase human comfort while doing work. (0 To set-up better physical working conditions. (g) To explore the ways for effective use of materials, tools machine, men and their movements. SAQ 1 Why is method study needed?

7.3 PROCEDURE OF METHOD STUDY

Different authors gave the method study procedure in slightly different steps. First of all, I L 0 proposed a baslicprocedure consisting of five steps as Select, Record, Examine, Develop and Define. Some authors have added few more steps to this with designing, installation, implementation, maintaining, etc. However, the standard procedure consists of the following six steps : (a) Select (b) Record (c) Examine (d) Develop (e) Install (0 Maintain These are briefed out in the following paragraphs. (The readers may remember these with an acronym SREDIM, made of first letters of the words, which means 'to stab'.) 7.3.1 Select Selection of problem is not as simple as one can think of. The problem identification involves a deep understanding into the methods and procedures followed to produce the product. However, industrial engineers have been provided with certain guidelines in selecting the problem and the tools for problem solving. These are given below : The Problem The problem is selected from the area or process where least yield is resulting or where loss of output is felt. The problem must be selected in such a way that it should be possible to solve and would get a feasible solution. A problem, which cannot be reduced to any solution and impracticable, should not be selected. For \lethod Study example, trying to find a generator which can start without external power and without any power loss is impossible. Also the problem selected should be as small as possible. Selection of a problem of large volume, which involves many people, can only become a mess. The problem selected should be defined precisely and distinctly. The Man Often, to solve the problem, the industrial engineer requires selecting an operator who can perform the modified method for defining the task and time study. The operator selected should be representative, i.e. the one who is selected should resemble to the group and normal in all respects such as efficiency, behaviour, skill, knowledge, etc. He should neither be highly skilled nor be unskilled. He should be neither highly efficient nor very low efficient and so on. He should have known all the parameters and phases of work. He must have willingness to work. He should be explained about the task, related job knowledge and concepts. He should be able to convince his co-workers with his achievements. The Machine Like the selection of man, the engineer conducting method study, needs to select a ~iiachinealso to take a decision on target fixation. The machine so selected should neither be new nor be old but in good operating conditions. It is better if the study is conducted on several machines to avoid unilateral decisions. The machines should be accurate and should repetitively give some results (precision) with a good process capability. The Material Material with good quality and specified properties should be provided. The Working Conditions The method study should be conducted at various combinations of working conditions ranging within ergonomically specified ranges. Also the experiments should be carried out at different times of a working day and different days of a month and at different seasons if required before standardising the methods. 7.3.2 Record After selecting a particular task for study, it is essential to record the relevant facts regarding different processes or procedures, inspection parameters, transport constraints and various basic resource requirements and availabilities. An effective recording methods, charts and diagrams can help the decision quickly, easily, correctly and timely. Various charts available and in common use are explained in two categories as Type-A and Type-B as follows : Charts Type-A : These charts show the process required by the task as per their sequence.

I Out line process chart Flow process chart-man type Flow process chart-material type Flow process chart-machine type

I Two handed process chart

I Type-B : These charts show the process on time scale according to their sequence. i Multiple activity chart I i PMTS chart Apart from the above charts, there are a few diagrams seldo~iiused in work-study. They are : Diagrams : Flow diagram String diagram Cycle graph Chronocycle graph Travel chart Rel chart A brief explanation of these charts is given at the end of this unit. 7.3.3 Examine After proper recording of the data, it is now important to examine these facts critically. All if s and but's could be brainstormed and some conclusions are to be drawn. These conclusions should be evaluated thoroughly from all the angles to choose best alternative. The pros and cons of each alternative should be written and a comparison chart is to be prepared if there are more than one good alternative by choosing suitable parameters for rating. 7.3.4 Develop Develop the most efficient alternative with high degree of accuracy. Measurements should be made impartially and see that there will not be any human errors while developing the method. It is very important to consider Economic, Technical and Human aspects during developing activity. The method should be clearly defined after developing it. Also the amount ofjob involved and standard should be calculated. 7.3.5 Install Prepare an implementation plan and install the new method. Choose a suitable period of time to watch the progress and efficiency of the method. It has been often reported by the industrial engineers about the resistance from employees to the new method. No doubt, the static friction is definitely more than dynamic friction. So also the human reactions for any new thing. The records and comparison charts will certainly become the useful tools to convince and authenticate the new method. 7.3.6 Maintain The final step of method study is in fact the most difficult part, to implement and maintain. 'The progress is to be recorded time to time and evaluated in suitable intervals. After a sufficient number of production runs and test readings, it is to be declared or standardised. However. it is essential to gain the acceptance from various supervisors, workers involved (sometimes even from union) and management and the workers orland supervisors are to be maintained properly to maintain the new method thereafter. Activity 1 Suppose you are the manager of a fast food centre. Conduct method study on 'toasting of bread'. Record your study as follows :

(a) Selection : Madmachine or equipmentlmaterial, etc. (b) Record : Existing method and all facts regarding the job is to be recorded by hletllod Study suitable toolltechnique.

...... (d) Develop : New method or modifications or rectification.

...... SAQ 2 (a) Explain the systematic procedure of method study. (b) "Method study is exploration of most economical way of doing work." Support the statement. \

7.4 MICRO-MOTION STUDY

It sometime becomes necessary to analyse the motions precisely and closely with a view that the unnecessary motion could be eliminated. It is worthwhile to perform such exercise on short cycles of movements, where the hand movements will be done thousands of times, e.g. assembly of certain electronic parts, packing, counting, etc. This study is known as MICRO-MOTION STUDY. All the movements are grouped up into certain common motions and are symbolised. These movements are called Micro-motions and the symbol given to represent such movement (micro-motion) is known as THERBLIG (GILBRETH spell reversely). These micro-motions are the outcomes of studies done by Frank Gilbreth and his wife Lillian Gilbreth. They also have given the short forms of letters or notations for these micro-motions. All together, there are seventeen (originally sixteen) micro-motions identified by Gilbreths. These are given in Table 7.1. In the micro-motions, there may be some confusion arisen in some micro-motions. For example, search and select in trying to identify a particular component among a group of components. In such case we take it as micro-motion. Similarly, it is difficult to discriminate between grasp and hold because holding often takes very short time (in such I cases hold can be eliminated). Gilbreth did not classify hold as a separate therblig, but considered as a part of grasp. But in some cases it is distinct and hence introduced. 1 i Suppose the electrode is held in one hand while working with welding torch with the 1 other hand. In such case it is quite distinct. When such confusion is there, the most ! suitable one is chosen. In fact, originslly sixteen therbligs were used in the micro-motion study. Out of the sixteen, thirteen are said to be active and three (AD, UD and R) are inactive. Later the seventeenth therblig PLAN (Pn) was introduced, which was also inactive. In fact, Gilbreth introduced these to analyse the hand, finger and eye motion, but later, Barnes changed the concept and applied them to analyse the motions of body members also. \Vark System Design Table 7.1 : Therbligs ! 1 ' Activity I Symbol Therblig 1 Colour Explanation 1 I 1 No. I

1. Assemble A Violet Putting the ob,jects together , - -#

- - Separating different parts of 1- Disassemble DA Light I 1 fl 1 the assembled unit 2. I Lemon A delay within operator's delay IADLD yellow control Unavoidable A delay on which operator has 1 AUD Yellow 4' 1 delay no control

Transport Moving an article from one TL - Green 1 I 1 lace to another

Transport 1 TE Olive green Moving (a body member, say 1 hand) empty empty 1 1I I I I I I 7. 1 Search Sh Black Hunting for an ob.ject

Mental reaction before action 8. Plan Pn Brown !

An allowance. idleness or Orange pause to overcome fatigue incurred during previous work

- - -~ Turning Lo line up, orient or 10. Position P 3 Blue 1 1 1 1 change position I i Mental reaction at the end of Find Sh Grey 11. aD search

Examining an object for its Burnt ochre quality

Locating an article in Preposition Pale blue predetermined position so that PP 1 0 it is ready for use Taking hold of something Red

Manipulating or causing a Purple tool to do its function

Retention (after grasp) Gold ochre

- Choosing one object from Select S > [,-- Light gray amongst many 1 e RL I /=' ( Carmine red ! Releasing an object Activity 2 Method Study Write the following jobslactivities with therbligs by splitting into elements : (a) Photo copying by Xerox machine......

...... (b) Preparation of omelet.

(d) Realising a cheque from Teller of a bank......

...... (e) Bowling and batting actions in a cricket match.

SAQ 3 (a) What do you understand by micro-motion study? (b) What is a THERBLIG? What is its significance in method study?

7.5 EQUIPMENT USED FOR MICRO-MOTION STUDY

In micro-motion study often we use the following equipment : (a) Motion picture camera (b) Micro chronometer (c) Motion picture projector with screen (d) Flood light arrangement (e) Steel cabinet for storing equipment and films Camera In the initial days, the camera used was hand-cranked type with 35 mm wide film with a speed of 100 frames per second. Later spring driven cameras with 16 mm and 18 mm film were also used. The camera was mounted on a tripod stand with photoflood lamps and reflections. Now-a-dap, hi-tech cameras are available with high degree of accuracy and speed. Video cameras are also in use now. \\ urk Systenl Delrlg~i Micro chronometer Since the speed of spring driven camera is not constant, an accurate timing device was required so that the time interval from one exposure to the next can be indicated on the film. Gilbreth developed a spring driven fast moving clock known as Micro chronometer, which is capable of indicating a minimum time of 112000th of a minute. The dial is divided into 100 equal parts, and the large hand makes 20 revolutions per minute while small hand makes 2 revolutions per minute. By changing gear ratio, further precise device is made to read 115000th minute. Cyclo-graph and Chrono-cycle Graph These two techniques were also developed by Gilbreth to analyse the path movement of the operator. Small electric bulbs are attached to the part of the body, which has to do movements. With the help of motion picture camera the photographs are taken to catch the path of body movement. This record is called cyclo-graph. This is a very good tool to trace the path but it does not provide any idea of direction of the motion. 'Therefore the illumination of the bulb is made slowly off and quickly on, so that they produce pear shape dots at higher illuminations to indicate direction, and speed of movement can also be calculated by measuring the distance between the dots. This record is known as chrono-cycle graph. The common data sheetslrecord sheets used in micro-motion study are given below : Table 7.2 : Motion Picture Data Sheet Location : ...... Film No. : ...... Operation : ...... Operation No. : ...... Part Name : ...... Film No. : ...... Machine Name : ...... Machine No. : ...... Department : ...... Date : ...... Operator's Name : ...... Einployee No. : ...... Experience on Job: ...... Material : ...... Beginning Time : ...... Finish Time : ...... Filming Time : ...... Camera Speed (Frameslsec) : ...... Camera Make : ...... Lens : ...... Type of Film : ...... Film Make : ...... Distance of Camera from Subject : ...... Exposure Reading : ...... Conclusions : ...... Remarks : ...... Table 7.3 : Micro-motion Study Sheet Part : ...... Department : ...... Operation : ...... Operation No. : ...... Operator : ...... Analysed by : ...... Film No. : ...... Sheet No. : ......

Therblig Description Clock Time Therblig Description (Symbol) I1 of Left Reading (Effective) (Symbol) I of Left i Iland lland 1 Operation Operation ------I I Activity 3 Method Study Imagine an operation of drilling a hole on a wooden block. Split the activity into elements and fill up the above tabular form with approximate (arbitrary) timings.

...... SAQ 4 (a) List out various tools and equipment used in micro-motion study. How are they applied? (b) What are the contents of a motion picture data sheet, and a micro-motion study sheet?

7.6 FACTORS TO BE CONSIDERED WHILE CONDUCING METHOD STUDY

While conducting method study, an engineer has to consider the following types of factors which form an acronym METHOD by the first letters of the factors : (a) Motion economy factors (b) Economic factors (c) Technical factors (d) Human factors (ej Operational complexity (f) Delays 7.6.1 Motion Economy Factors When a particular job is undertaken for study, one has to think of whether there is a possibility of reducing number of motions. In regular jobs that are performed, the micro-motion studies revealed that there are such unnecessary motions in plenty. By economising these motions, we can save human energy and re-use it for higher productivity. There are evidences in various operations, which are repetitive in nature such as packing, counting, assembly of components, the micro-motion studies have replaced with tactful activities and easy methods that have saved a lot of human energy. Gilbreth has practically shown this in brick laying, which had increased the efficiency almost three-fold. 7.6.2 Economic Factors Obviously, one has to think if it is worth while to conduct motion or micro-motion study. If a work selected for investigation results in a very small economy, it is of no use. (Otherwise it follows a Hindi saying that "Char anna murgee ke liye barah anna masala", which means it is foolish to spend 75 paise on spices to cook a chicken worth 25 paise. Or in other words it is loosing dollars for pennies.) Hence it is very important for an engineer to estimate or forecast, "how far the method study of a job will produce extra or how much additional productivity we may get and how much money or energy or material we can save by the studies? etc." While finding the answers to such questions one may have to consider the economy in removing the bottlenecks in movements and \\'ark System Design process such as movement of materials froin one operation to the other, layout of machines. operational sequences (in accordance with technological factors), etc. 7.6.3 Technical Factors When a new method is developed and implemented, it is required to check availability of adequate technical know-how and technological resources. Obviously, this feature limits the scope of selection of development of new methods. Machine replacement analysis. job seclueilciilg and other operational research techniclues which are available to evaluate technical factors. In most of the cases, teclmical factors and economic factors are inter- linked. Sometimes, it may be highly economic and sometimes hardly economic, and some other times there may be no effect when technological improvements are made. However, this factor depends on the company policies and the situations that prevail. 7.6.4 Human Factors It is very difficult for an engineer to evaluate these factors because it is associated with pl~ysiological,psychological and anatomical features. Rut the researchers have proved that these difficulties can be overpowered to some extent through scientific methods such as ergonomics. However, there will not be much problem to evaluate and implement the new methods in accordance with human factors if workers and their representatives are included to participate from the stage of formulation of problem (selecting) to implementation (install and maintain). The full and active participation from the workers side and a due consideration to their views from the management's side would reduce the difficulties and gives an impression in the workers that the new methods are for their betterment. 7.6.5 Operational Complexity All operations are not alike. Some operations will be complex to operate while some others are easy. Some are flexible and some are rigid. Some are gray collared and some are white. When a method study is taken up for a job, most often the managers forget to take such operational complexity/flexibility into consideration. It is engineer's responsibility to bring out detailed description about the operational flexibility or complexity so that the critical examination can be facilitated to check under these constraints. After developing the method if such problems arise, all the efforts will become futile. And the money, energy and time spent on such researches go waste. Perhaps, this is the reason why Japanese stress on planning at machine table rather than to plan at office table. 7.6.6 Delays There are three types of delays. The first is unavoidable delay, where the operation or operator inevitably waits for the material :o come or for his turn to do job, etc. The process demands this delay for example, heat treated products have to be cooled before an operation on a certain machine, welded joints are allowed to cool before taken for operation, etc. In second type, the avoidable delays can be avoided by proper planning. For example, a machinist need not have to wait if the brooming or cleaning is done prior to his arrival. The third type of delay are 'planned rest pauses'. These are also inevitable but somewhat flexible to change their schedules or durations in accordance with ergonomics studies. The industrial engineers who conduct method study must take these delays into consideration while developing the new method. Activity 4 Suppose you have to establish a standard method for electroplating, for which you are conducting method study. What factors do you consider? List out and explain. SAQ 5 Method Study (a) Explain the factors that are to be taken care while conducting a method study. (b) With reference to method study write short notes on (i) Economic factors (ii) Technical factors (iii) Human factors.

7.7 TOOLS OF METHOD STUDY

Recording Techniques The success of any research depends on the right method of recording the facts with the tools that projects accurately. Various techniques available for method study are classified under four heads. These are : (a) Charts (A-Type) Charts (B-Type) (b) Diagrams (c) Models (d) Photographic aids. Charts These are again classified into two types. These are A-type and B-type. A-type charts indicate the sequence of events happening in the order, which they occur irrespective of time scale, whereas B-type charts indicate the sequence of happening in the order in which they occur on a time scale. The charts, which are in common use, are listed below :

(a) Operation process chart (b) Flow process chart - man typelmaterial typelequipment type (c) Two hand process chart B-Type : (a) Man-machine chart (b) Man-material chart (c) Multiple activity chart (d) SIMO chart (e) PMTS chart The above charts are prepared using some standard symbols. These symbols are established by American Society of Mechanical Engineers (ASME) which are ur~iversallyaccepted for preparing chart. Before learning how to prepare charts, it is essential to know these symbols. These are described in Table 7.4. Table 7.4 : Symbols Used in Method Study I 1 Symbol 1 Activity 1 Mcani~~g/Explanstion ! 1 OI'ERATION 1 Process or method or procedure olthe 1 i job under action of producing or .- . I 1 1.modr t~cat~onor conversion or scrvicc 1 I , ! / INSPECTION / Checking li)r quality or ma~erialor work / I I or process of products or service or j I ! / method or ~nanage~nent I i f -- I Movement of ~iiatesialor men or 1 equipment ofmachine from one place to I another I 1 I\ DDEI.AY ) Lateness or delay in the sequence of ,i / events or a temponry storage ofilaiting 1 of a job for the nest operation 1 STORAGE Controlled storage/p~.eservationof the i I material received or to be issued in the I i form of saw or semi-processed or i finished goods Sometimes. we may find that an operation itself is transpul-ting or storing is an operation, etc. In such case we show as one inscribed in the other. An example is shown below : SYMBOL Transportation is the operation such as public transport by a Road Transport Corporation bus.

Now, a brief description is given for each type of chart in the following paragraphs Operation Proccss Chart It is a technique of recording the work elements involved in a process in a compact manner for easy understanding and fast reproducing by means of a set of chart symbols. It provides a "bird's eye view7' on the process and is defined as "the chart giving an overall picture by recording sequence only with main operations and inspections". Hence, the main elements viz., operation and inspection are recorded in this chart irrespective of who does it, where is it carried out, when is it done? And how much duration does it take? Process chart sheet format is given in Table 7.5.

Table 7.5 : Process Chart Sheet Existing/Proposed : ...... Date : ...... Type of Chart : ...... Charted by : ......

Activity : ...... Chart No. : ......

Department : ...... Sheet No. : ......

Beginning of Activity : ...... Ending of Activity : ......

1 Distance in Metres 1 Chart Symbol / Process Description I I

I I iI

I I Method Stud)

Activity/Symbol Number

rransportat~on Inspect~on

Advantages Operation process chart is found highly useful because (a) ir represents basic activities a: a sumrnarised overall picture. (b) it is easy for a lay-man (non-technical man) also to understand as it visualises the process. (c) it gives a scope for improvement of operations or their sequence by combination or rearrangement or elimination. (d) it helps in identifying the stages of inspection and thus provides an idea for better layout of work place. (e) it helps in tracing the material. (f) it shows a way to think of improvements in material handling and reducing the material movements. !* Flow Process Chart It is an improved version of operation process chart, which is set out sequence of flow of a product. man or machine or material by recording all events in its process, in terms of appropriate symbols. ASME defines the flow process chart as "a graphic representation of the sequence of all operations, transportations, inspections, delays and storages occurring during a process or procedure and includes information considered desirable for analysis such as time required and distance moved". Advantages In addition to the advantages shown in operation process chart, this has some more advantages such as a complete picture in detail with what happens to the material (material type), which worker does? (Man type), the equipment used at each stage of operations (machine type). It also gives the distance moved orland time taken at each stage. Further, the chart includes the transportations, delays and storages in the process along with operations and inspections. This enables the engineer to plan the operations and schedule them accurately. Flow process chart is as shown in Table 7.6. Table 7.6 : Flow Process Chart (ManIMateriallMachine Type) Method : ExistingIProposed Machine No. : Operation : Operation No. : Operator : Charted by : Start of Activity : End of Activity : Department : Date :

------Distance Symbol - Description \\'orl\ Svstem Design

Proposed i saving4 Overation I I / 'Transportation )

I Storage CV) I Delay (D ) 1 I Inspection to? 1 - I Distance in Mtrs. 1 Two-hand Process Chart This chart is used to study the motions of two hands or limbs of worker and bring out the effectiveness and hence the efficiency. It is defined as "a process chart in the activities of a worker's hands or limbs are recorded in relationship to each other". This technique is widely used for micro-motion study where the jobs with short and complicate work-cycle can easily be studied. Two-hand process chart is as shown in Table 7.7. Table 7.7 : Two Hand Process Chart Method : Existing/Proposed Machine No. : Operation : Operation No. : Operator : Charted by : Stan of Activity : End 01' Activity : Department : Date : 1 Description Right Hand OIVDU OIVDU OIVDU OIVDO OIVDO OIVDD OIVDO OIVDO OIVDO OIVDO OIVDO OIVDO OIVDO OIVDO OIVDO OIVDU OIVDO OIVDO OIVDO OIVDO OIVDO OIVDU OIVDO OIVDU OIVDO OIVDU

Summury

ActivityISyrnbol Existing Proposetl Saving

1 Oneration (0 1 Transportation (a) 1 1 Storage (0) I I Delay . (D I lnspection (0) -1 1 kncein Mtrs. Activity 5 Method Study Draw a process chartlflow process chartltwo-hand chart for the following jobs : (a) Toasting of bread

...... (b) Juice making

...... (d) Dent removing and painting of a car ......

Multiple Activity Chart In all the above, the chart can tell us about only one of resources like either a worker or an equipment or material, etc. But the relation between a man and machine or man and material, etc. are not known. The multiple activity chart can give all these in a very compact manner. This chart enables the industrial engineer to study whether any unnecessary waiting times can be eluded. The multiple activity charts are prepared in one of the four ways as follows (a) One man - one machine chart (b) Two men - one machine chart (c) One man -two machine chart (d) Two or more men - one or more machine chart Advantages The major advantages of this chart are to use as a tool for finding the optimum number of machines and operators, capacity calculations, incentive calculations, man-power planning, material planning, job scheduling, etc. The charts like SIMO chart, PMTS chart are explained in time study, Unit 1 1, of the same block. Diagrams A diagram is more powerful tool of recording as it looks attractive, eye catching and is easy to understand than charts, even without any prerequisite knowledge of techniques or the process. The most popular diagrams used in work-study are briefed out hereunder. Flow Diagram A plan of work area on scale with the accurate location of facilities is a flow diagram. The symbols used for flow-chart can also be used here. An example is as shown in Figure 7.1, which explains the serving dinner in a hospital ward, in two methcds, by proposed method distance saved is about 54 percent (refer ILO - Introduction to Work Study). Work System Design 9 Metes nnn

Beds .--___- Beds

~oorT P Original Method I i - - - - Improved method Figure 7.1 : Flow Diagram String Diagram There will be many situations that the workers or the material may have to be moved between the workstations many times a day. To reduce the total distance moved or to modify the layout or to plan the locations, these diagrams are very much helpful. The existinglproposed points or workstations where the workerslmaterial are expected to move will be traced to scale on a board. And these will be pinned or nailed. A long thread or string is passed through the pegs in various alternatives to choose optimal distance by the length of thread. An example is shown in Figure 7.2.

Figure 7.2 : String Diagram In the above string diagram it is to be understood from the double lines that there are frequent motions between those work centres for example, between A-G and B-F. The layout can be modified by keeping such centres of frequent motion close or together. Obviously, the distance moved can be reduced and the handling problems can be controlled. -- - -

Activity 6 hlcthod Study (a) In the above string diagram, find out the layout that reduces the total distance covered, by various alternatives and also find the route that minimises the total distance travelled by using string.

(b) Suppose you are a sales executive for company which has the marketing centres at New Delhi, Kolkata. Bangalore, Hyderabad, Mumbai, Chennai and Jaipur. You got to visit all these centres in the shortest duration as well as at least cost. All the centres are connected one another by airways. Take an Indian map and construct the string diagram to find the shortest path. Record your results under three colum~~s-Experiment No., Route, Length of string (Total distance).

Travel Chart or Trip Frequency Chart Though the above two are powerful tools to record the movement of menimateriallequipment, a limitation or recording number of movements and the direction of movements are still remaining. Moreover, they require a complexive setup and are time consuming. A tabular form makes it much simpler and removes all those confusions. Thus the travel chart can be defined as "the tabular record for representing quantitative data about the movement of workers, materials or equipment between any number of places over a given period of time". The following example shows it very clearly from which one can understand easily that from the first row there are three motions from station-1 to station-2, two from station-1 to station4 and one from station-1 to station-8 which summarises as six from station-1 to various places. Similarly, one can read all the rows as well as columns. (The summary is also shown row wise and column wise in Table 7.8.) Table 7.8 : Travel Chart or Trip Frequency Chart

SUMMARY OF MOVEMENTS (FROM STATIONS)

I 1411015l7/5!10l8l7 Activity 7 Construct a travel chart for regular motions of various departmental interactions in your organisation or the organisations with which you are most familiar. Work Systeni Design Rel Cha,rt Its full name is relationship chart. Here the relationship between various departments can be understood by the help of which the layout of departments can be made optimally so as to reduce the distance of motions by keeping highly related departments nearer. This relationship is usually based on the number of movements among the departments and often makes use of travel chart for reading the number of motions. The re1 chart uses the notations as vowzls A. E, I, 0. Wand one consonant X for representing the relations. The relations are A for Absolutely necessary E for Essential D for Important 0 for Ordinary U for Unimportant X for No relation A relation chart is shown in Figure 7.3. It is to be read by the cell intersected by paths drawn from respective departments. For example, relation between production and planning from the below chart can be read as 'A', i.e. absolutely necessary.

Production Department

Finance Department

Planning Department

Personnel Department

Security Department

Figure 7.3 : Rel Chart or Relationship Chart Activity 8 Construct a REL chart for various departments of your organisation or the one, which is most familiar to you. Establish the priority of the departments in relationship with your department.

The diagrams like cycle graph and chrono cycle graph are already explained under micro-motion study and hence not explained here again. Readers may go through them and consider here also. Models Models are the tools of recording techniques, which visualise in a better manner than charts and diagrams. A layman can also understand so easily and it gives clear picture for the worker who is expected to have less technical knowledge. Method Study Hence these may be treated as worker's tools of work study while charts and diagrams are engineer's tools. The models are classified as three types. These are templates, two-dimensional models and three-dimensional models. Templates The area required by machines including inspections, storage area, conveyors, etc. cut to scale from a sheet or thick paper or hard board or plywood or fibre. Colours may be used to show the distinction. Usually the colour codes used are as follows :

GREY : Production machines GREEN : Benches and racks and stationary equipment YELLOW : Conveyors

RED : Storage area Two-dimensional Models It seems that there is no difference between a two-dimensional model and a template as both are made of same materials. But the templates are used to show layout of machines while two-dimensional models are used only for machines smaller than two metres. Both these are used for achieving improvement in layouts. Three-dimensional Models These models are made of wood or thermocoal or ply-wood or hard board in three dimensions in a suitable scale to represent the actual layout or machine or job. These are also used for demonstration to visitors and for trainees. These are supposed to be high degrse visualising tools for the study. Photographic Aids These are the tools often used in micro-motion study. These are explained under the head micro-motion study of the same unit. Readers are advised to refer back. Activity 9 Prepare a template or a model (with thermocoal material) for the department where you are working and colour the areas in it. Write what colours you used for various areas and cross check with the standard code.

SAQ 6

(a) Write an essay on +herecording techniques used in method study. (b) With appropriate charts/tables/data sheets, write short notes on : (i) A-type charts (ii) B-type charts (i ii) Diagrams (iv) Models Work System Design (c) With an example of your choice explain the structure of: (i) Travel chart (ii) Rel chart

(d) What is the significance of the following tools of method study? (i) Templates (ii) Photographic aids (iii) Operation process chart.

(e) Explain the symbols and their meanings along with their applications, used in representing method study information through flow/process charts.

(f) List out and compare the advantages and limitations of each recording technique used in method study.

7.8 SUMMARY

Method study is one of the oldest tool for improvement of the methods for the present modem world. But, this tool is powerful and a convenient to layman. Perhaps, the reason is that it is the most convincing concept to managers, proprietors, owners, workers or any group of people. This is because of its characteristics incorporated through the human aspects (to satisfy the workers and managers), economic aspects (to satisfy the owners and proprietors) and technological aspects (to satisfy the engineers and managers). These characteristics have made it everlasting. However, any concept will give its fruits when and only when top management believes it completely and encourages the middle management or lower management to conduct such studies with a thorough understanding. The method study and its procedure are discussed at length in this unit. It can be understood through a single word 'SREDIM' (Select, Record, Examine, Develop, Install and Maintain). Then the contributions of F. Gilbreth and L. Gilbreth are discussed in this unit through their micro-motion study, which took the work-study in a new direction. It facilitated a thorough and root level study ofjobs by the introduction of symbols and 'Therbligs' by Gilbreth. It has been provided a right place for his works in this unit. The equipment used for micro-motion study such as motion picture camera. cycle graph, chrono-cycle graph, etc. have been explained. The method study caters many people by the virtue of its characteristics. These are explained as factors such as Motion Economy factors, Economic factors, Technic11 factors, Human factors, Oper3tional complexity and Delays to be consiJered while METHOD study is conducted. In Method study the use of its tools like Chaits (A and B-Type), Diagr~ms,Models, Templates and Photographic aids are widely employed and are exemplified in this unit.

7.9 KEY WORDS - -

SREDIM : It is an acronym used to represent the procedure of method study, which is composed of first letters of the words Select, Record, Examine, Develop, Install (or Implement) and Maintain. Select It is the first step of method study. It concerns 5letl1od Study with the problem identification and the selection of right men, material, machine, took and equipment and the suitable environmental conditions for conduction of method study. Record The second step of method study that demands the representation of the existing method and the proposed method to perform the selected job. Examine This step (the third step of method study) deals with the critical evaluation of the recorded (Existing and Proposed) data. Develop After critical examination of the prevailing and proposed methods, a suitable method is designed and developed. lnstall It is the implementation of the developed model or method of several experimentations during the examination and development phases. Maintain The final step of method study that concerns with the maintaining the method for certain specified time to see the results of the study. Micro Motion Study The study that analyses the motions precisely and closely with a view that the unnecessary motion could be eliminated. This uses the symbols and therbligs to record and examine the micro level motion. Therblig The symbolic representations of various body actions such as grasp, load, unload, etc. introduced by Gilbreth. Micro Chronometer Gilbreth developed a spring driven fast moving clock, which is capable of indicating a minimum time of 112000th of a minute. The dial is divided into 100 equal parts, and the large hand makes 20 revolutions per minute while small hand makes 2 revolutions per minute. Developed by Gilbreth to analyse the path movement of the operator by attaching small electric bulbs to the part of the body, which has to do movements and recording through photographs taken by motion picture camera. Chrono-cycle Graph Developed by Gilbreth to analyse the path of movement of the operator by attaching small electric bulbs whose illumination of the bulb is made slowly off and quickly on (they produce pear shape dots at higher illuminations and indicate direction and speed of movement) to the part of the body, which has to do movements and recorded through photographs taken by motion picture camera. SIMO Chart Simultaneous Motion chart is the chart that is used to analyse by recording the motions of both hands when under motion simultaneously. This is recorded by motion picture camera. Work System Design String Diagram : The diagram used to reduce unnecessary motions and handling by using a string on layout diagram drawn to scale. Travel Chart or : The tabular form or chart that gives the details of Trip Frequency Chart number of motions that occur among all the work stations in a given time. Rel Chart : It is the chart that gives the Relationship among the work centres such as A - Absolutely necessary, E - Essential, I - Important, 0 -Ordinary, U - Unimportant and X -No P-elation.

7.10 ANSWERS TO SAQs

Refer the relevant preceding text in this unit for answers to SAQs.