METHOD STUDY. Definition: WHY:

Transcription

1 1

2 METHOD STUDY Definition: It is a systematic recording and critical examination of existing and proposed ways of doing work, as a means of developing and applying easier and more effective methods and reducing costs. WHY: The improvement of processes and procedures. The improvement of factory, shop and workplace layout. The improvement of the design of plant and equipment. Economy in human effort and the reduction of unnecessary fatigue. Improvements in the use of materials, machines and manpower. The development of a better physical working environment. Improvement of quality of the products. 2

3 Recording Techniques in Method study Indicating Process Sequence Outline process chart Using a time scale Multiple activity chart Diagrams indicating movements Flow Diagrams Flow process chart Man type chart Material type chart Machine type chart Two -Handed process chart Simo chart P.M.T.S. chart String Diagram Cycle Graph Chrono-cycle Graph Travel Chart 3

4 1.Operation Process Chart Symbols Indicates the main steps in a process, method or procedure. Usually the part, material or product concerned is modified or changed during the operation. 2.Inspection Indicates an inspection for quality and / or check for quantity 3.Transport Indicates the movement of workers, materials or equipment from place to place 4

5 4.Temporary Storage or Delay Indicates a delay in the sequence of events : for example, work waiting between consecutive operations, or any object laid aside temporarily without record until required. 5.Permanent Storage Indicates a controlled storage in which material is received into or issued from a store under some form of authorization; or an item is retained for reference purposes. 6.Combined Activities Indicates a controlled storage in which material is received into or issued from a store under some form of authorization; or an item is retained for reference purposes. 5

6 E X A P M L E S Figure: 6

7 Outline Process Chart Definition: An outline process chart is a process chart giving an overall picture by recording in sequence only the main operations and inspections. While preparing the outline process chart we use Symbols of Operation and Inspection A brief note of the nature of each operation is made beside the symbol In an outline process chart, only the principal operations and the inspections carried out are recorded to ensure effectiveness 7

8 Example: Outline process chart of plywood manufacture is given 8

9 Flow process charts Definition: Flow process charts are graphic representations of the sequences of operations, transportation, inspections, delays and storages occurring during a process or a procedure and include information considered for analysis such as, time required and distance moved. To develop an understanding how a process or work happening and clearly documenting how a particular job is done, in addition of that mapping a process in flow chart format helps us where the process can be improved. 9

10 Types of Flow Process Charts Material or product type. Man type. Machine type or equipment. Material or product type flow process chart:- Records what happens to the material or product i.e. the changes the material or product undergoes in location or condition (includes operation and transportation). Man type process flow process chart:- Records the activities of worker or operator i.e. what a worker or operator does. In this type of chart usually storage term is not applicable. Machine or equipment type flow process charts:- Records the manner in which a machine or an equipment is used. 10

11 STANDARD FORMATS USED FOR FLOW PROCESS CHART 11

12 Job:- Writing a letter using a shorthand typist 12

13 Example: Collection of materials from store (Man Type) 13

14 Material type flow process chart 14

15 Machine type flow process chart Job : Assembly of flange at shrink fitting m/c. 15

16 Two Hand Process Chart Two-Handed Flow Process Chart, is a motion study where the study is done to analyse the motions used by the worker in performing an activity. In this chart the activities of a worker s hands (or limbs) are recorded in their relationship to one another. A Two-Handed Process Flow Chart individually shows the movement of each hand in a manual process. It is typically used for repetitive operation when analyzing a manual assembly process, to help make it easier to perform. 16

17 Why: The objective of this investigation is to eliminate or reduce the unwanted motions and to arrange the remaining motions in a best sequence. How: A two-handed process chart is made up of two columns in which the activities of the left hand and right hand and the appropriate symbols are respectively recorded in sequence. The activities of the two hands are inter-related by aligning the symbols on the chart so that movements by both hands appear opposite to each other. Additional columns can be designed to record the activities of the other parts of the body whenever necessary. 17

18 Operation Transport Delay Hold Inspection An operation occurs when the hand grasps, releases or assembles tool, material, component etc. Transport occurs when the hand moves from one position to another at the work place. Delay occurs when the hand is Idle in the sense that it is not performing any activity. The term storage is not used in connection with the two handed process chart. Instead the symbol is re designated as hold. A hold occurs when the hand holds an object so that the other hand may be able to do something to that object. This symbol is not generally used in this. 18

19 Standard format of a Two-handed process flowchart 19

20 Fig. 1. Example of a Two-handed process flowchart Fixing Screw on a Assembly 20

21 Fig. 1. Example of a Two-handed process flowchart Fixing Screw on a Assembly 21

22 MULTIPLE ACTIVITY CHART A Chart in which the activities of more than one item are recorded on a common time scale to show their interrelationship. Man machine chart is the type of multiple activity charts. TYPES: Man - Machine chart: One man handling one job or one machine. Man - Multi machine chart: One man handling a numbers of machines. Machine Multi - man chart: A group or gang doing collectively one job as in riveting. Multi Man - Machine chart: A number of persons working on a computer system. 22

23 MULTIPLE ACTIVITY CHART Definition: A Multiple activity chart is a form of process chart recording the related sequence of work of a number of operators and/or machines on common time scale. In it, the activities of more than one item, worker, machine or equipment are recorded on a common time scale to show their inter relation ship. Why: Multiple Activity Charts are very useful tool for understanding the flow of work in a cyclic process and as a consequence understanding which resource is controlling the overall progress of the work. The tool can be used to model different scenarios to determine the optimum mix of resources for the work. 23

24 Multiple activity chart brings out the comparative utilisation of men and machines very clearly and helps to synchronise the various activities and improve the situation. It is a useful tool for planning team work and determining the staffing pattern. The multiple activity charts shows up clearly the periods of ineffective time and by rearrangement of work it becomes possible to eliminate or reduce the injective time. How: Activities of the machines are recorded in relation to that of the operator, the chart is sometimes called as the man machine chart; This is only a special variant of the multiple activity chart 24

25 Example on Man Machine Chart (Present Method) TIME (MIN) MAN MACHINE TIME (MIN) 0.2 Remove finished casting cleans with compressed air 0.4 Gauge depth of slot on surface plate IDLE 0.2 IDLE PLACE in a box obtains new casting 1.0 Cleans machine with compressed air 1.2 Locates castings in fixture, starts machine IDLE 0.8 IDLE 1.0 IDLE IDLE Cutting slot IDLE Cutting slot IDLE Cutting slot IDLE Cutting slot

26 EXAMPLE ON MAN MACHINE CHART (Summary of Present method) CYCLE TIME(MIN)= 2.0 Man Machine Working Time (min.) Idle Time (min.) Utilizatio n (%) MAN % MACHINE % 26

27 Example on Man Machine Chart (Improved Method) TIME (MIN) MAN 0.2 REMOVED FINISHED CASTING CLEANS WITH COM PRESED AIR MACHI NE TIME (MIN) IDLE CLEAN MACHINE WITH COMPRESED AIR 0.6 LOCATEES A NEW CASTING IN A FIXTURE START MACHINE IDLE 0.4 IDLE BREAKS SHARP EDGES WITH FILES CLEANS WITH COMPRESSED AIR 1.0 GAUGE DEPTH OF SLOT ON SURFACE PLATE 1.2 PLACES CASTING IN A BOX PICKS UP NEW CASTING AND PLATE BY MACHINE CUTTING SLOT 1 CUTTING SLOT 2 CUTTING SLOT IDLE CUTTING SLOT

28 EXAMPLE ON MAN MACHINE CHART (Summary of Improved method) CYCLE TIME(MIN)= 1.4 Man Machine Working Time (min.) Idle Time (min.) Utilizatio n (%) MAN % MACHINE % 28

29 PRESENT METHOD CYCLE TIME (MIN) MAN IDLE TIME(MIN ) MACHINE IDLE TIME ( MIN) IMPROVED METHOD

30 Micro motion study Micro motion study is the study of fundamental element or subdivision of an operation by means of a motion picture camera and a timing device which accurately indicates the time interval on motion picture film. Micro motion study provides a valuable technique for making minute analysis of those operation that are short in cycle contain rapid movement and involve high production over a long period of time. For example. Sewing of garment, assembly of small parts. 30

31 Applicable for operations with very short cycles which are repeated thousands of times. Goes into greater details to determine where movements and efforts can be saved and to develop the best possible patterns of movements. Enables operators to perform the operation repeatedly with minimum effort and fatigue. The technique used for this typically involves filming the operation and hence is known as micromotion study. Examples of operators studied could be cashier in the bank routine job of taking payment slips from customer and issuing cash! 31

32 Based on the idea that human activity can be divided into movements or group of movements (therbligs) according to the purpose for which they are made. The therbligs cover movements or reasons for the absence of movement. Each therblig has specific color, symbol and letter for recording purposes. Therbligs refer primarily to motions of the human body at the workplace and to the mental activities associated with them. 32

33 They permit a much more precise and detailed description of the work than any other method described. Considerable practice is required in identification of therbligs before they can be used for analysis with confidence. 33

34 Main advantages of films over visual methods are: Permit greater detailing than eye observation; Provide greater accuracy than pencil, paper and stop watch; More convenient; Provide a positive record; Help in the development of the work study person. 34

35 Objective of Micro motion study 1. To find most efficient way of doing work 2. Helps to study repetitive short cycle operation which cannot be studied by ordinary method. 3. To train operator regarding motion economy. 4. It is permanent means of keeping record of method. 5. It assists in research project in the field of work study 6. It helps to study complex activities of short duration performed with extreme rapidity. 35

36 Procedure/ Step in micro motion study 1. Filming the operation to be studied. 2. Analyzing the film. 3. Charting the result of analysis. 4. Developing and improve method. Filming :- The filming speed is 16 frames per second with a 16 mm movie camera. Film Analysis:- 1.A Projector is used for analysis purpose. 2. Projector runs the films very slowly and film can be stopped & reversed whenever required. 36

37 EQUIPMENT REQUIRED mm film. 2. Movie Camera. 3. wink counter. Exposure meter. Motion picture projector with screen 37

38 A record of path of movements, usually traced by a continuous source of a light on a photograph. The path of movement of a hand, may be recorded on a photograph by putting a ring carrying small light on worker s hand. A path of light resembling a white wire is seen. Later it is used with a stereoscopic camera to show the path in three dimensions. 38

39 Light (bulb) attached to the hand 39

40 This is a development of the cycle graph by interrupting the flow of current so as to obtain, in the resulting sequence of flashes, a record of the time and direction of the motions under observation. The resulting image was a chronocyclograph. The path of light appears as a series of pear-shaped dots, the movement being in the direction in which the dots point. The spacing between the dots indicate the speed of movement and show acceleration and deceleration. This is done by using a turning fork, which is vibrating at a known speed, and connected with a make and break contact. 40

41 41

42 42

43 43

44 Diagrams Diagrams gives pictorial view of the layout of workplace on which locations of different equipment, machines etc. are indicated. The movement of subject(man or machine) is then indicated on the diagram by a line or a string. The diagram are valuable in highlighting the movement so the analyst can take steps to simplify or reduce it so as to obtain saving in time. The most commonly used method study diagrams are: o Flow diagram o String diagram o Travel chart o Cyclegraph and Chronocyclegraph 44

45 Flow diagram It s a top view of the work area correctly indicating the positions of machining and other locations affecting the movement of subject. Therefor it gives on-the-spot observation of the paths of movement of product sometimes using symbols of process charts. 45

46 A scale plan or model on which a thread is used to trace and measure the path of workers, material or equipment. A thread is used to measure distance. Necessary that the string diagram be drawn correctly to scale, whereas regular flow diagram can be drawn only approximately to scale. Thus, string diagram and flow chart can give clearest possible picture of what is actually being done. String diagram can be used to plot movements of material to know how far the materials travel. Most commonly, the string diagram is used for plotting the movements of workers. 46

47 Examples 0 10ft 47

48 FOLD DRILL+CUT RIVET MARK OQC IQC SHEET METAL START END STACK 48

49 Travel chart String diagram is good to explain movements and critical examination but o it takes longer time to get constructed and o many movement along complex paths may lead to a diagram with maze of crisscrossing line. Therefore, when movements are very complex travel chart is quick and more effectively manageable recording technique. How is it made? o A travel chart is a tabular record for pressing quantitative data about the movements of subject between any numbers of places a over a given period of time. o This chart is a square table and each square within table represents a station. o It has number of rows and columns equal to the number of stations that can be visited by the subject. 49