Industrial Engineering - MOTION STUDY , CRITICAL EXAMINATION & RELATED TOPICS

CRITICAL EXAMINATION

CRITICAL EXAMINATION:

CRITICAL EXAMINATION OF THE INFORMATION RECORDED ABOUT THE PROCESS IN CHARTS / DIAGRAMS IS THE MOST IMPORTANT PHASE OF THE METHOD STUDY. IN THIS, EACH ELEMENT OF THE WORK, AS PRESENTLY BEING DONE AND RECORDED ON THE CHART IS SUBJECTED TO A SYSTEMATIC AND PROGRESSIVE SERIES OF QUESTIONS WITH THE PURPOSE OF DETERMINING TRUE REASONS FOR WHICH IT IS DONE. BASED ON THE REASONS, IMPROVEMENTS ARE FOUND AND ADOPTED INTO A NEW METHOD, CALLED BETTER METHOD. THIS EXAMINATION, THUS REQUIRES EXHAUSTIVE COLLABORATION WITH EVERYONE WHO’S CONTRIBUTION CAN PROVE USEFUL, AND ALSO FULL USE OF ALL AVAILABLE SOURCES OF TECHNICAL INFORMATION. THE USE OF QUESTIONING TECHNIQUE REDUCES THE POSSIBILITY OF MISSING ANY INFORMATION WHICH MAY BE USEFUL FOR THE DEVELOPMENT OF BETTER METHOD.

A POPULAR PROCEDURE OF CARRYING OUT CRITICAL EXAMINATION USES TWO SETS OF QUESTIONS: PRIMARY QUESTIONS (ANSWERS TO THESE SHOW UP THE NECESSITY OF CARRYING OUT THE ACTIVITY), AND SECONDARY QUESTIONS (ANSWERS TO THESE ALLOW CONSIDERATIONS TO ALTERNATIVE METHODS OF DOING THE ACTIVITY). SELECTION OF THE BEST WAY OF DOING EACH ACTIVITY IS LATER DETERMINED TO DEVELOP NEW METHOD WHICH IS INTRODUCED AS A STANDARD PRACTICE.

A GENERAL-PURPOSE SET OF PRIMARY AND SECONDARY QUESTIONS IS GIVEN BELOW:

PRIMARY QUESTIONS:

PURPOSE - THE NEED OF CARRYING OUT THE ACTIVITY IS CHALLENGED BY THE QUESTIONS-WHAT IS ACHIEVED? IS IT NECESSARY? WHY? THE ANSWERS TO THESE QUESTIONS DETERMINE WHETHER THE PARTICULAR ACTIVITY WILL BE INCLUDED IN THE PROPOSALS OF NEW METHOD FOR THE PROCESS.

MEANS - THE MEANS OF CARRYING OUT THE ACTIVITY ARE CHALLENGED BY THE QUESTIONS- 'HOW IS IT DONE?' AND 'WHY THAT WAY'?

PLACE - THE LOCATION OF CARRYING OUT THE ACTIVITY IS CHALLENGED BY THE QUESTIONS- 'WHERE IS IT DONE'? AND 'WHY THERE'?

SEQUENCE - THE TIME OF CARRYING OUT THE ACTIVITY IS CHALLENGED BY THE QUESTIONS- 'WHEN IS IT DONE'? AND 'WHY THEN'?

PERSON - THE LEVEL OF SKILL AND EXPERIENCE OF THE PERSON PERFORMING THE ACTIVITY IS CHALLENGED BY THE QUESTIONS- 'WHO DOES IT'? AND 'WHY THAT PERSON'?

THE MAIN OBJECT OF THE PRIMARY QUESTIONS IS TO MAKE SURE THAT THE REASONS FOR EVERY ASPECT OF THE PRESENTLY USED METHOD ARE CLEARLY UNDERSTOOD. THE ANSWERS TO THESE QUESTIONS SHOULD CLEARLY BRING OUT ANY PART OF THE WORK WHICH IS UNNECESSARY OR INEFFICIENT IN RESPECT OF MEANS, SEQUENCE, AND PERSON OR PLACE.

SECONDARY QUESTIONS:

THE AIM OF SECONDARY QUESTIONS IS TO ARRIVE AT SUITABLE ALTERNATIVES TO THE PRESENTLY USED METHOD:

PURPOSE - IF THE ANSWER TO THE PRIMARY QUESTION 'IS THE ACTIVITY NECESSARY"? IS CONVINCINGLY 'YES', ALTERNATIVES TO ACHIEVE THE OBJECT OF CARRYING NUT THE ACTIVITY ARE CONSIDERED BY THE QUESTION— 'WHAT ELSE COULD BE DONE'?

MEANS - ALL THE ALTERNATIVE MEANS TO ACHIEVE THE OBJECT ARE CONSIDERED BY THE QUESTION— 'HOW ELSE COULD IT BE DONE'?

PLACE - OTHER PLACES FOR CARRY ING OUT THE ACTIVITY ARE CONSIDERED BY THE QUESTION— 'WHERE ELSE COULD IT BE DONE'?

SEQUENCE - THE SECONDARY QUESTION ASKED UNDER THIS HEADING IS— 'WHEN ELSE COULD IT BE CLONE'?

PERSON - THE POSSIBILITIES FOR CARRYING OUT THE ACTIVITY BY OTHER PERSONS ARE CONSIDERED BY ASKING THE QUESTION- 'WHO ELSE SHOULD DO IT’?

THIS PHASE INVOLVES THE SEARCH OF ALTERNATIVE POSSIBILITIES WITHIN THE IMPOSED RESTRICTIONS OF COST, VOLUME OF PRODUCTION, AND THE LIKE. FOR THIS THE METHOD STUDY MAN USES HIS OWN PAST EXPERIENCE WITH SAME OR SIMILAR PROBLEMS OR REFERS TO TEXT BOOKS, HANDBOOKS, ETC.

THE ANSWERS TO THE FOLLOWING QUESTIONS ARE THEN SOUGHT THROUGH EVALUATION OF THE ALTERNATIVES.

'WHAT SHOULD BE DONE'?

'HOW SHOULD IT BE DONE'?

'WHERE SHOULD IT BE DONE'?

'WHEN SHOULD IT BE DONE'? AND

'WHO SHOULD DO IT'?

THESE ANSWERS FORM THE BASIS OF THE PROPOSALS FOR THE IMPROVED METHOD. THE EVALUATION PHASE REQUIRES THE WORK STUDY MAN TO CONSIDER ALL THE POSSIBILITIES WITH RESPECT TO THE FOUR FACTORS—ECONOMIC, SAFETY, WORK QUALITY AND HUMAN FACTORS—THE ECONOMIC FACTOR BEING THE MOST IMPORTANT IN MOST SITUATIONS. 

ECONOMIC CONSIDERATIONS TO ANY ALTERNATIVE REFER TO DETERMINATION OF 'HOW MUCH WILL IT COST'? AND 'HOW MUCH WILL IT SAVE'? THE PURPOSE OF EVALUATING SAFETY FACTOR IS TO ENSURE THAT THE ALTERNATIVE SELECTED SHALL NOT MAKE THE WORK LESS SAFE. THE EVALUATION OF QUALITY FACTOR SHALL DETERMINE WHETHER THE ALTERNATIVE SELECTED SHALL MAKE FOR BETTER PRODUCT QUALITY OR QUALITY CONTROL.

AND LASTLY HUMAN FACTORS CONSIDERATIONS SHALL ENSURE THAT THE NEW METHOD WILL BE INTERESTING, EASY TO LEARN, SAFE, LESS MONOTONOUS AND LESS FATIGUING TO THE OPERATOR.

WITH THE PRESENT METHOD OR PROCEDURE FOR THE JOB IN MIND, THE APPLICATION OF ‘CRITICAL ANALYSIS' HIGHLIGHTS THE ESSENTIAL PART OF THE JOB, FOR WHICH ALTERNATIVE WAYS FOR ITS CARRYING OUT ARE DEVELOPED .

WHEN DEVELOPING ALTERNATIVE WAYS FOR DOING A TASK THE FOLLOWING MAY BE CONSIDERED.

• WHERE AND HOW TO USE ‘MAN' IN THE PROCESS?
• WHAT BETTER WORK PROCEDURE BE ADOPTED?
• WHAT BETTER EQUIPMENT BE USED?
• WHAT BETTER LAYOUT OF WORK STATION, SHOP OR FACTORY BE USED?

IN DECIDING WHETHER A PARTICULAR ELEMENT OF WORK (OPERATION, INSPECTION, OR TRANSPORTATION) BE CARRIED OUT MANUALLY OR WITH THE HELP OF A DEVICE, METHOD STUDY ENGINEER MUST BE WELL AWARE OF THINGS WHICH MAN CANNOT DO OR DOES IN INFERIOR FASHION THAN MACHINE. EXAMPLES OF SUCH THINGS ARE: 

• EXERT LARGE AMOUNT OF FORCE, AS NEEDED IN METAL CUTTING.
• EXERT FORCE PRECISELY OR SMOOTHLY AT A FIXED RATE AS NEEDED IN METAL FORMING.
• DO HIGH SPEED COMPUTATIONS OF COMPLEX NATURE.
• PERFORM REPETITIVE TASKS WITHOUT SUFFERING FROM SIDE EFFECTS LIKE BOREDOM, FATIGUE, ETC.
• MOVE AT HIGH SPEEDS FOR HOURS TOGETHER.
• CARRY OUT SEVERAL TASKS SIMULTANEOUSLY.
• RESPOND FAST TO FREQUENTLY CHANGING CONTROL SIGNALS.
• PERFORM SATISFACTORILY IN AN ENVIRONMENT WHERE CONDITIONS RELATING TO COLD, HEAT, NOISE, DAMPNESS, ETC. ARE EXTREME.

IN CONTRAST, MACHINES PROVE INFERIOR GENERALLY WHEN FOR CARRYING OUT A TASK IT IS NECESSARY TO

THINK CREATIVELY OR INDUCTIVELY

• LEARN
• GENERALIZE
• COPE WILL UNEXPECTED EVENTS. 

IN MOST CASES, THE RELATIVE ROLES OF MAN AND MACHINE VARY FROM ONE EXTREME END IN WHICH ENTIRE PROCESS IS MANUAL TO THE OTHER EXTREME IN WHICH THE PROCESS IS COMPLETELY MECHANIZED WITH THE PRESENCE OF MAN ONLY FOR MONITORING, TROUBLE SHOOTING, MAINTENANCE, AND THE LIKE. 

MAN IS READILY AVAILABLE AND EXTREMELY FLEXIBLE TOOL, WHO HAS THE CAPABILITY OF DOING A LARGE NUMBER AND TYPE OF TASKS WITH LEARNING AND PRACTICE THAT IS GENERALLY LESS EXPENSIVE THAN THE COST OF CREATING DEVICES FOR THE SAME PURPOSE. MAN IS THEREFORE CONSIDERED A STRONG COMPETITOR FOR LOW, MEDIUM AND EVEN SOME HIGH VOLUME PRODUCTION TASKS. 

WHEN AN ACTIVITY IS DECIDED TO BE CARRIED OUT MANUALLY, THE BEST WORK PROCEDURE IS DETERMINED BY CONSIDERING THE PRINCIPLES OF MOTION ECONOMY.

EQUIPPED WILL THE VARIOUS ALTERNATIVE WAYS OF CARRYING OUT ESSENTIAL ELEMENTS OF TASK, METHOD STUDY ENGINEER HAS NOW TO CHOOSE THE BEST ALTERNATIVE METHOD? HE DECIDES UPON THE CRITERIA, WHICH MAY BE ADDITIONAL FIXED COSTS INVOLVED, RUNNING COST, PRODUCTION RATE, OPERATOR'S FATIGUE, OPERATOR LEARNING TIME, AND THE LIKE. THE WEIGHT TO EACH CRITERION IS FIXED AND PERFORMANCE IS PREDICTED OF EACH ALTERNATIVE WITH RESPECT TO EACH CRITERIA. THE ONE WHICH GETS THE MAXIMUM POINTS IS SELECTED FOR ADOPTION AS A STANDARD METHOD. 

DETAILED SPECIFICATIONS OF THIS METHOD ARE PREPARED WITH THE DESCRIPTION OF PROCEDURE, WORKPLACE LAYOUT AND MATERIAL/EQUIPMENT TO BE USED. THIS IS IMPORTANT FOR 

• COMMUNICATION OF THE PROPOSED WORK METHOD TO THOSE RESPONSIBLE FOR ITS APPROVAL
• COMMUNICATION OF THE PROPOSED METHOD TO THOSE CONCERNED WITH ITS INSTALLATION, FOR EXAMPLE INSTRUCTORS AND SUPERVISORS WHO ARE ACTUALLY RESPONSIBLE FOR INSTRUCTIONS TO OPERATORS AND SETTING UP THE MACHINERY AND WORK PLACE LAYOUTS.
• OFFICIAL RECORD OF THE WORK METHOD.

INSTALLATION OF IMPROVED METHOD:

WHEN THE PROPOSALS OF THE IMPROVED METHOD FOR A JOB ARE APPROVED BY THE MANAGEMENT OF THE COMPANY, THE NEXT STEP IS TO PUT THIS METHOD INTO PRACTICE. INSTALLATION OF METHOD REQUIRES NECESSARY PRIOR PREPARATION FOR WHICH THE ACTIVE SUPPORT OF EVERYONE CONCERNED IS VERY IMPORTANT. 

THE ACTIVITIES OF THE INSTALLATION PHASE INCLUDE:

GAINING ACCEPTANCE OF THE CHANGE BY THE WORKERS INVOLVED AND THEIR REPRESENTATIVES. THE METHOD CHANGE MAY AFFECT THE ROUTINE AND PAPER WORK OF WAGES, COSTS, PLANNING, AND EVEN PURCHASE DEPARTMENT. IT MAY REQUIRE DISPLACEMENT OF STAFF FROM ONE SECTION TO ANOTHER OF THE ORGANISATION. ADJUSTMENTS OF THIS TYPE NEED TO BE CARRIED OUT VERY CAREFULLY SO THAT THE LEAST POSSIBLE HARDSHIP OR INCONVENIENCE IS CAUSED. 

RETRAINING THE WORKERS. THE EXTENT TO WHICH WORKERS NEED RETRAINING WILL DEPEND ON THE NATURE OF THE JOB AND THE CHANGES INVOLVED. IT IS MUCH MORE FOR THOSE JOBS WHICH HAVE A HIGH DEGREE OF MANUAL DEXTERITY AND WHERE THE WORKERS HAVE BEEN DOING THE WORK BY TRADITIONAL METHODS. THE USE OF FILMS DEMONSTRATING THE ADVANTAGES OF NEW METHOD AS COMPARED TO TRADITIONAL ONE ARE OFTEN VERY USEFUL IN RETRAINING THE WORKERS. 

ARRANGING THE REQUIREMENTS OF THE NEW METHOD. THIS INVOLVES-

• ARRANGING THE NECESSARY PLANT, TOOLS AND EQUIPMENT AT ALL THE WORKPLACES,
• ARRANGING BUILDING-UP OF NECESSARY STOCKS OF NEW RAW MATERIALS, AND RUNNING-DOWN OF OLD STOCKS,
• CHECKING UP THE AVAILABILITY AND CONTINUITY OF ALL SUPPLIES AND SERVICES, AND
• ARRANGING ANY CLERICAL RECORDS WHICH MAY BE REQUIRED FOR PURPOSES OF CONTROL AND COMPARISON.

TAKING OTHER NECESSARY ACTIONS. THESE WILL DEPEND UPON SITUATION TO SITUATION. FOR EXAMPLE, IF CHANGES IN WORKING HOURS ARE INVOLVED, NECESSARY INSTRUCTIONS SHOULD BE PASSED ON TO AUXILIARY SERVICES SUCH AS TRANSPORT, CANTEEN, WATER SUPPLY, ETC. IF CHANGE IN WAGES IS INVOLVED, INFORMATION CONCERNING THE DATE OF INSTALLATION MUST REACH THE COSTING DEPARTMENT. NECESSARY INSTRUCTIONS SHOULD BE PASSED ON TO EVERY ONE CONCERNED ABOUT THE TIME TABLE FOR THE INSTALLATION OF THE CHANGE IN METHOD. 

GIVING A TRIAL RUN TO THE NEW METHOD. IT IS IMPORTANT THAT ALL DEPARTMENTS AFFECTED BY THE CHANGE ARE REPRESENTED AT THE REHEARSAL. IT IS OFTEN ADVANTAGEOUS TO CONDUCT THE REHEARSAL WHILE THE OLD METHOD IS STILL OPERATING. IT SHOULD USUALLY TAKE PLACE OUTSIDE NORMAL WORKING HOURS; SAY AT WEEK-END OR AT HOLIDAY TIME SO THAT THERE IS NO INTERFERENCE WITH NORMAL PRODUCTION. THE SUGGESTIONS FOR MINOR VARIATIONS IN THE PROPOSED METHOD IF THEY ARE WORTH WHILE AND COST EFFECTIVE SHOULD BE ACCEPTED AND INCORPORATED. 

IT IS OBVIOUS THAT THE METHOD ANALYST HAS TO BE EXTRA TACTFUL AND KEEP RESTRAINT THROUGHOUT THE PERIOD OF INSTALLATION. THE INSTALLATION IS CONSIDERED COMPLETE WHEN THE NEW METHOD STARTS RUNNING SMOOTHLY.

FOLLOW-UP:

THE WORK OF METHOD STUDY MAN IS NOT COMPLETE WITH THE INSTALLATION OF THE IMPROVED METHOD; THE MAINTENANCE OF THE NEW METHOD IN ITS SPECIFIED FORM IS ALSO PART OF HIS ACTIVITIES. THE MAIN AIM OF MAINTENANCE OF THE NEW METHOD IS TO ENSURE THAT THE WORKERS DO NOT SLIP BACK INTO OLD METHOD, OR INTRODUCE ELEMENTS WHICH ARE NOT PART OF THE PROPOSED METHOD. 

FOR EFFECTIVE MAINTENANCE IT IS IMPORTANT TO DEFINE AND SPECIFY THE NEW METHOD VERY CLEARLY. AN OPERATOR CHART GIVING ADEQUATE DETAILS OF THE TOOLS, EQUIPMENT, AND WORKPLACE LAYOUT AND OPERATOR-MOTION PATTERN IS OFTEN HELPFUL.

THE WORKERS HAVE TENDENCY TO DRIFT AWAY FROM THE METHOD LAID DOWN. THE PURPOSE OF THE METHOD-MAINTENANCE IS TO CHECK THIS TENDENCY. BUT IF IT IS FOUND THAT THE CHANGE FROM THE METHOD SPECIFIED IS IN FACT AN IMPROVEMENT WHICH CAN BE MADE IN THE METHOD, THIS SHOULD BE OFFICIALLY INCORPORATED. 

MOTION STUDY

MOTION STUDY IS A TECHNIQUE OF ANALYZING THE BODY MOTIONS EMPLOYED IN DOING A TASK IN ORDER TO ELIMINATE OR REDUCE INEFFECTIVE MOVEMENTS AND FACILITATES EFFECTIVE MOVEMENTS. BY USING MOTION STUDY AND THE PRINCIPLES OF MOTION ECONOMY THE TASK IS REDESIGNED TO BE MORE EFFECTIVE AND LESS TIME CONSUMING.

THE GILBRETHS PIONEERED THE STUDY OF MANUAL MOTIONS AND DEVELOPED BASIC LAWS OF MOTION ECONOMY THAT ARE STILL RELEVANT TODAY. THEY WERE ALSO RESPONSIBLE FOR THE DEVELOPMENT OF DETAILED MOTION PICTURE STUDIES, TERMED AS MICRO MOTION STUDIES, WHICH ARE EXTREMELY USEFUL FOR ANALYZING HIGHLY REPETITIVE MANUAL OPERATIONS. WITH THE IMPROVEMENT IN TECHNOLOGY, OF COURSE, VIDEO CAMERA HAS REPLACED THE TRADITIONAL MOTION PICTURE FILM CAMERA. 

IN A BROAD SENSE, MOTION STUDY ENCOMPASSES MICRO MOTION STUDY AND BOTH HAVE THE SAME OBJECTIVE: JOB SIMPLIFICATION SO THAT IT IS LESS FATIGUING AND LESS TIME CONSUMING. WHILE MOTION STUDY INVOLVES A SIMPLE VISUAL ANALYSIS, MICRO MOTION STUDY USES MORE EXPENSIVE EQUIPMENT. THE TWO TYPES OF STUDIES MAY BE COMPARED TO VIEWING A TASK UNDER A MAGNIFYING GLASS VERSUS VIEWING THE SAME UNDER A MICROSCOPE. THE ADDED DETAIL REVEALED BY THE MICROSCOPE MAY BE NEEDED IN EXCEPTIONAL CASES WHEN EVEN A MINUTE IMPROVEMENT IN MOTIONS MATTERS, I.E. ON EXTREMELY SHORT REPETITIVE TASKS.

TAKING THE CINE FILMS @ 16 TO 20 FRAMES PER SECOND WITH MOTION PICTURE CAMERA, DEVELOPING THE FILM AND ANALYZING THE FILM FOR MICRO MOTION STUDY HAD ALWAYS BEEN CONSIDERED A COSTLY AFFAIR. TO SAVE ON THE COST OF DEVELOPING THE FILM AND THE COST OF FILM ITSELF, A TECHNIQUE WAS USED IN WHICH CAMERA TOOK ONLY 5 TO 10 FRAMES PER MINUTE. THIS SAVED ON THE TIME OF FILM ANALYSIS TOO. IN APPLICATIONS WHERE INFREQUENT SHOTS OF CAMERA COULD PROVIDE ALMOST SAME INFORMATION, THE TECHNIQUE PROVED FRUITFUL AND ACQUIRED THE NAME MEMO MOTION STUDY.

TRADITIONALLY, THE DATA FROM MICRO MOTION STUDIES ARE RECORDED ON A SIMULTANEOUS MOTION (SIMO) CHART WHILE THAT FROM MOTION STUDIES ARE RECORDED ON A RIGHT HAND - LEFT HAND PROCESS CHART.

THERBLIGS:

ON ANALYZING THE RESULT OF SEVERAL MOTION STUDIES CONDUCTED, GILBRETHS CONCLUDED THAT ANY WORK CAN BE DONE BY USING A COMBINATION OF SOME OR ALL OF 17 BASIC MOTIONS, CALLED THERBLIGS (GILBRETH SPELLED BACKWARD). THESE CAN BE CLASSIFIED AS EFFECTIVE THERBLIGS AND INEFFECTIVE THERBLIGS. EFFECTIVE THERBLIGS TAKE THE WORK PROGRESS TOWARDS COMPLETION. ATTEMPTS CAN BE MADE TO SHORTEN THEM BUT THEY CANNOT BE ELIMINATED. INEFFECTIVE THERBLIGS DO NOT ADVANCE THE PROGRESS OF WORK AND THEREFORE ATTEMPTS SHOULD BE MADE TO ELIMINATE THEM BY APPLYING THE PRINCIPLES OF MOTION ECONOMY. 

SIMO CHART:

IT IS A GRAPHIC REPRESENTATION OF AN ACTIVITY AND SHOWS THE SEQUENCE OF THE THERBLIGS OR GROUP OF THERBLIGS PERFORMED BY BODY MEMBERS OF OPERATOR. IT IS DRAWN ON A COMMON TIME SCALE. IN OTHER WORDS, IT IS A TWO-HAND PROCESS CHART DRAWN IN TERMS OF THERBLIGS AND WITH A TIME SCALE.

MAKING THE SIMO CHART. A VIDEO FILM OR A MOTION PICTURE FILM IS SHOT OF THE OPERATION AS IT IS CARRIED OUT BY THE OPERATOR. THE FILM IS ANALYZED FRAME BY FRAME. FOR THE LEFT HAND, THE SEQUENCE OF THERBLIGS (OR GROUP OF THERBLIGS) WITH THEIR TIME VALUES ARE RECORDED ON THE COLUMN CORRESPONDING TO THE LEFT HAND. THE SYMBOLS ARE ADDED AGAINST THE LENGTH OF COLUMN REPRESENTING THE DURATION OF THE GROUP OF THERBLIGS. THE PROCEDURE IS REPEATED FOR THE RIGHT HAND AND OTHER BODY MEMBERS (IF ANY) INVOLVED IN CARRYING OUT THE OPERATION.

IT IS GENERALLY NOT POSSIBLE TO TIME INDIVIDUAL THERBLIGS. A CERTAIN NUMBER OF THERBLIGS MAY BE GROUPED INTO AN ELEMENT LARGE ENOUGH TO BE MEASURED

USES OF SIMO CHART:

FROM THE ANALYSIS SHOWN ABOUT THE MOTIONS OF THE TWO HANDS (OR OTHER BODY MEMBERS) INVOLVED IN DOING AN OPERATION, INEFFICIENT MOTION PATTERN CAN BE IDENTIFIED AND ANY VIOLATION OF THE PRINCIPLE OF MOTION ECONOMY CAN BE EASILY NOTICED. THE CHART, THEREFORE, HELPS IN IMPROVING THE METHOD OF DOING AN OPERATION SO THAT BALANCED TWO-HANDED ACTIONS WITH COORDINATED FOOT AND EYE MOTIONS CAN BE ACHIEVED AND INEFFECTIVE MOTIONS CAN BE EITHER REDUCED OR ELIMINATED. THE RESULT IS A SMOOTHER, MORE RHYTHMIC WORK CYCLE THAT KEEPS BOTH DELAYS AND OPERATOR FATIGUE TO THE MINIMUM EXTENT. 

References: - www.nptel.iitm.ac.in/