Description
This is a presentation about line balancing.
LINE BALANCING
WHAT IS LINE BALANCING ?
LINE BALANCING IS THE ARRANGING OF PRODUCTION LINE SO THAT THERE IS EVEN FLOW OF PRODUCTION UNITS FROM ONE WORK STATION TO THE NEXT.
LINE BALANCING PROBLEMS ARE THOSE OF MINIMISING IDLE TIME ALONG THE PRODUCTION LINE RESULTING FROM UNEQUAL TASKS TIMES ASSIGNED TO THE VARIOUS STATIONS
TYPES OF LINE BALANCING PROBLEMS
PRODUCTION LINES
FABRICATION LINES
ASSEMBLY LINES
CONSISTING OF FAB. OPERATIONS ( I.E. THOSE CHANGE SHAPE OR FORM) E.G. MACHINING OPERATIONS
CONSISTING OF PURELY ASSEMBLY OPERATIONS
FABRICATION LINES ARE DIFFICULT TO BALANCE WHY ? -MACHINING OPERATIONS ARE DIFFICULT TO SPLIT -PRECEDENCE RELATIONSHIPS ARE TIGHTER -MACHINE TOOLS CAN BE EMPLOYED FOR RESTRICTED VARIETY OF JOBS HOW DO WE HANDLE PROBLEMS ? ARRANGE MACHINE TOOLS AS PER SEQUENCE OF OPERATIONS
? DUPLICATE MACHINES ( BOTTLENECKS) ? METHODS IMPROVEMENT (BOTTLENECKS) ? CHANGE SPEEDS/FEEDS ? ALLOW PARTS TO BANK ON SLOWER MACHINES (OT/EXTRA SHIFT) ? DIVERT PARTS TO BANK ON OTHER MACHINES ? PROVIDE BUFFER ? IMPROVE PERFORMANCE
TERMINOLOGY
1. PRODUCTION LINE : ( A GENERAL TERM FOR ASSEMBLY LINE) REPRESENTS AN ARRANGEMENT OFWORK STATIONS WHERE EACH WORKMAN PERFORMS A PRE-DETERMINED TASK ON A INCOMPLETE UNIT WHICH PASSES DOWN THE LINE OF SUBSEQUENT STATIONS UNTIL IT IS FINISHED
2. WORK STATIONS : REPRESENTS AN ASSIGNED LOCATION/ZONE/ PLACE/STAGE IN AN ASSEMBLY LINE WHERE A DESIGNATED WORK ( A COMBINATION OF WORK ELEMENTS) IS PERFORMED ON THE PART OR COMPONENT OR SUB-ASSEMBLY OF THE PRODUCT.
3. STATION WORK CONTENT : REPRESENTS TIME REQUIRED TO PERFORM THE DESIGNATED WORK AT A GIVEN WORK STATION. STATION WORK CONTENT = SUM OF TIME OF ALL WORK ELEMENTS ALLOTED TO A WORK STATION.
4. WORK ELEMENT : REPRESENTS THE SMALLEST PORTION OF WORK IDENTIFIED DURING THE BREAKDOWN ANALYSIS OF THE JOB. 5. ASSEMBLY WORK CONTENT : REPRESENTS SUM OF WORK CONTENTS OF ALL WORK STATIONS ALONG THE PRODUCTION LINE n ASSEMBLY WORK CONTENT = ? Wi I WHERE Wi = WORK CONTENT OF ith STATION n = NO. OF STATIONS
6. CYCLE TIME : REPRESENTS THE TIME AFTER WHICH A FINISHED UNIT ( PRODUCTION) COMES OFF THE PRODUCTION LINE. CYCLE TIME IS DICTATED BY PRODUCTION RATE
CYCLE TIME = TIME OF A BOTTLENECK IN A OPERATION FABRICATION LINE
7. DELAY TIME : REPRESENTS IDLE TIME OF A WORK STATION. DELAY TIME OF A = di = C-Wi WORK STATION ( ith STATION) 8. BALANCE DELAY : REPRESENTS THE EFFICIENCY OF THE BALANCING PROCESS OF THE PRODUCTION LINE. BALANCE DELAY = SUM OF IDLE TIME AT ALL STATIONS WORKING TIME OF ALL STATIONS
= ? di i n.C
n
n
x100
= ? C - Wi x100 i n.C 9. LINE EFFICIENCY (?) : MEASURES THE UTLISATION OF EMPLOYEES. n LINE EFFICIENCY (?) = ? Wi i n.C OR LINE EFFICIENCY (?) = 100- BALANCE DELAY
STEPS IN DESIGN OF A PRODUCT LAYOUT LINE BALANCING
STEP 1 : SELECT THE JOB/WORK FOR WHICH PRODUCTION LINE/ASSEMBLY LINE IS TO BE SETUP
STEP 2 : BREAKDOWN THE TOTAL WORK INTO ELEMENTAL TASKS ( OR STEPS) E.G DRILLING A HOLE IS ONE STEP
STEP 3 : ESTABLISH PRECEDENCE REQUIREMENTS BETWEEN THE ELEMENTAL TASKS AND CONSTRUCT A PRESEDENCE DIAGRAM.
STEP 4 : SELECT A FEASIBLE CYCLE TIME
STEP 5 : DETERMINE THE MINIMUM NUMBER OF WORK STATIONS.
STEP 6 : SELECT A SUITABLE HEURISTIC TECHNIQUE AND ASSIGN ELEMENTAL TASKS TO INDIVIDUAL WORK STATIONS. - PREDECESSOR NUMBERS TECHNIQUE ( KILBRIDGE & WESTER METHOD) - RANKED POSITIONAL WEIGHT TECHNIQUE ( HELGESON AND BIRNIE METHOD)
STEP 7 : CALCULATE DEFFECTIVENESS AND EFFICIENCY OF THE LINE BALANCING.
STEP 8 : SEEK FURTHER IMPROVEMENTS
1. PRECEDENCE DIAGRAM
PRECEDENCE DIAGRAM IS THE GRAPHICAL ANALYSIS OF SEQUENCE IN WHICH ELEMENTAL TASKS CONSTITUTING THE ASSEMBLY MUST BE PERFORMED. FOR TECHNICAL REASONS OR REASONS OF SAFETY/CONVENIENCE
LISTING OF WORK ELEMENTS
REPRESENTING BY NODES JOINING NODES BY ARROWS TO INDICATE THE DIRECTION OF FLOW
INTERPRETION OF PRECEDENCE DIAGRAM
H B E A
C
F
I
D
G
2. PREDECESSOR NUMBERS TECHNIQUE
STEP 1 : CONSTRUCT THE PRECEDENCE DIAGRAM FOR THE WORK ELEMENTS STEP 2 : GROUP THE WORK ELEMENTS IN COLUMNS. STEP 3 : SELECT THE FEASIBLE CYCLE TIME AND DETERMINE THE MINIMUM NUMBER OF WORK STATIONS
STEP 4 : PROCEED COLUMN BY COLUMN, FROM LEFT TO RIGHT AND ASSIGN WORK ELEMENTS TO THE STATION SUCH THAT – (i) THE WORK ELEMENT WITH THE LARGEST TIME IS CHOSEN FIRST (ii) THE SUM OF THE ELEMENTAL TIMES DOES NOT EXCEED THE CYCLE TIME (C) IF THE STATION TIME EXCEEDS TIME DUE TO INCLUSIONS OF A WORK ELEMENT, THEN SUCH AS ELEMENT IS ASSIGNED TO THE NEXT STATION.
STEP 5 : DELETE THE ASSIGNED WORK ELEMENTS AND REPEAT STEP 3 FOR THE REMAINING WORK ELEMENTS.
STEP 6 : REPEAT STEPS 4 TO 5 UNTIL ALL WORK ELEMENTS ARE ASSIGNED TO WORK STATIONS.
3. RANKED POSITIONAL WEIGHT TECHNIQUE
STEP 1 : CONSTRUCT THE PRECEDENCE DIAGRAM FOR THE WORK ELEMENTS INVOLVED STEP 2 : DETERMINE THE POSITIONAL WEIGHT FOR EACH WORK ELEMENT (A POSITIONALWEIGHT OF AN OPERATION REPRESENTS THE MAXIMUM TIME FROM THE BEGINNING OF WORK ELEMENT THROUGH THE REMAINDER OF THE NETWORK.)
STEP 3 : RANK WORK ELEMENTS ACCORDING TO THEIR POSITIONAL WEIGHTS IN STEP 2 BEGINNING WITH WORK ELEMENT WITH THE HIGHEST POSITIONAL WEIGHT DOWN THE ONE WITH THE SMALLEST POSITIONAL WEIGHT. STEP 4: CONSIDERING THE PRESEDENCE RELATIONSHIP, ASSIGN THE WORK ELEMENT WITH THE HIGHEST POSITIONAL WEIGHT TO THE FIRST STATION.
STEP 5 : IF ANY UNALLOCATED TIME REMAINS AFTER ASSIGNMENT OF WORK ELEMENT, ASSIGN THE NEXT SUCCEEDING RANKED WORK ELEMENTS TO THE STATION WITHOUT VIOLATING THE PRECEDENCE RELATIONSHIPS AND WITHOUT LETTING THE STATION TIME EXCEED THE CYCLE TIME. STEP 6 : REPEAT STEPS 4 & 5 UNTIL ALL WORK ELEMENTS ARE ASSIGNED TO THE WORK STATIONS.
doc_256172449.ppt
This is a presentation about line balancing.
LINE BALANCING
WHAT IS LINE BALANCING ?
LINE BALANCING IS THE ARRANGING OF PRODUCTION LINE SO THAT THERE IS EVEN FLOW OF PRODUCTION UNITS FROM ONE WORK STATION TO THE NEXT.
LINE BALANCING PROBLEMS ARE THOSE OF MINIMISING IDLE TIME ALONG THE PRODUCTION LINE RESULTING FROM UNEQUAL TASKS TIMES ASSIGNED TO THE VARIOUS STATIONS
TYPES OF LINE BALANCING PROBLEMS
PRODUCTION LINES
FABRICATION LINES
ASSEMBLY LINES
CONSISTING OF FAB. OPERATIONS ( I.E. THOSE CHANGE SHAPE OR FORM) E.G. MACHINING OPERATIONS
CONSISTING OF PURELY ASSEMBLY OPERATIONS
FABRICATION LINES ARE DIFFICULT TO BALANCE WHY ? -MACHINING OPERATIONS ARE DIFFICULT TO SPLIT -PRECEDENCE RELATIONSHIPS ARE TIGHTER -MACHINE TOOLS CAN BE EMPLOYED FOR RESTRICTED VARIETY OF JOBS HOW DO WE HANDLE PROBLEMS ? ARRANGE MACHINE TOOLS AS PER SEQUENCE OF OPERATIONS
? DUPLICATE MACHINES ( BOTTLENECKS) ? METHODS IMPROVEMENT (BOTTLENECKS) ? CHANGE SPEEDS/FEEDS ? ALLOW PARTS TO BANK ON SLOWER MACHINES (OT/EXTRA SHIFT) ? DIVERT PARTS TO BANK ON OTHER MACHINES ? PROVIDE BUFFER ? IMPROVE PERFORMANCE
TERMINOLOGY
1. PRODUCTION LINE : ( A GENERAL TERM FOR ASSEMBLY LINE) REPRESENTS AN ARRANGEMENT OFWORK STATIONS WHERE EACH WORKMAN PERFORMS A PRE-DETERMINED TASK ON A INCOMPLETE UNIT WHICH PASSES DOWN THE LINE OF SUBSEQUENT STATIONS UNTIL IT IS FINISHED
2. WORK STATIONS : REPRESENTS AN ASSIGNED LOCATION/ZONE/ PLACE/STAGE IN AN ASSEMBLY LINE WHERE A DESIGNATED WORK ( A COMBINATION OF WORK ELEMENTS) IS PERFORMED ON THE PART OR COMPONENT OR SUB-ASSEMBLY OF THE PRODUCT.
3. STATION WORK CONTENT : REPRESENTS TIME REQUIRED TO PERFORM THE DESIGNATED WORK AT A GIVEN WORK STATION. STATION WORK CONTENT = SUM OF TIME OF ALL WORK ELEMENTS ALLOTED TO A WORK STATION.
4. WORK ELEMENT : REPRESENTS THE SMALLEST PORTION OF WORK IDENTIFIED DURING THE BREAKDOWN ANALYSIS OF THE JOB. 5. ASSEMBLY WORK CONTENT : REPRESENTS SUM OF WORK CONTENTS OF ALL WORK STATIONS ALONG THE PRODUCTION LINE n ASSEMBLY WORK CONTENT = ? Wi I WHERE Wi = WORK CONTENT OF ith STATION n = NO. OF STATIONS
6. CYCLE TIME : REPRESENTS THE TIME AFTER WHICH A FINISHED UNIT ( PRODUCTION) COMES OFF THE PRODUCTION LINE. CYCLE TIME IS DICTATED BY PRODUCTION RATE
CYCLE TIME = TIME OF A BOTTLENECK IN A OPERATION FABRICATION LINE
7. DELAY TIME : REPRESENTS IDLE TIME OF A WORK STATION. DELAY TIME OF A = di = C-Wi WORK STATION ( ith STATION) 8. BALANCE DELAY : REPRESENTS THE EFFICIENCY OF THE BALANCING PROCESS OF THE PRODUCTION LINE. BALANCE DELAY = SUM OF IDLE TIME AT ALL STATIONS WORKING TIME OF ALL STATIONS
= ? di i n.C
n
n
x100
= ? C - Wi x100 i n.C 9. LINE EFFICIENCY (?) : MEASURES THE UTLISATION OF EMPLOYEES. n LINE EFFICIENCY (?) = ? Wi i n.C OR LINE EFFICIENCY (?) = 100- BALANCE DELAY
STEPS IN DESIGN OF A PRODUCT LAYOUT LINE BALANCING
STEP 1 : SELECT THE JOB/WORK FOR WHICH PRODUCTION LINE/ASSEMBLY LINE IS TO BE SETUP
STEP 2 : BREAKDOWN THE TOTAL WORK INTO ELEMENTAL TASKS ( OR STEPS) E.G DRILLING A HOLE IS ONE STEP
STEP 3 : ESTABLISH PRECEDENCE REQUIREMENTS BETWEEN THE ELEMENTAL TASKS AND CONSTRUCT A PRESEDENCE DIAGRAM.
STEP 4 : SELECT A FEASIBLE CYCLE TIME
STEP 5 : DETERMINE THE MINIMUM NUMBER OF WORK STATIONS.
STEP 6 : SELECT A SUITABLE HEURISTIC TECHNIQUE AND ASSIGN ELEMENTAL TASKS TO INDIVIDUAL WORK STATIONS. - PREDECESSOR NUMBERS TECHNIQUE ( KILBRIDGE & WESTER METHOD) - RANKED POSITIONAL WEIGHT TECHNIQUE ( HELGESON AND BIRNIE METHOD)
STEP 7 : CALCULATE DEFFECTIVENESS AND EFFICIENCY OF THE LINE BALANCING.
STEP 8 : SEEK FURTHER IMPROVEMENTS
1. PRECEDENCE DIAGRAM
PRECEDENCE DIAGRAM IS THE GRAPHICAL ANALYSIS OF SEQUENCE IN WHICH ELEMENTAL TASKS CONSTITUTING THE ASSEMBLY MUST BE PERFORMED. FOR TECHNICAL REASONS OR REASONS OF SAFETY/CONVENIENCE
LISTING OF WORK ELEMENTS
REPRESENTING BY NODES JOINING NODES BY ARROWS TO INDICATE THE DIRECTION OF FLOW
INTERPRETION OF PRECEDENCE DIAGRAM
H B E A
C
F
I
D
G
2. PREDECESSOR NUMBERS TECHNIQUE
STEP 1 : CONSTRUCT THE PRECEDENCE DIAGRAM FOR THE WORK ELEMENTS STEP 2 : GROUP THE WORK ELEMENTS IN COLUMNS. STEP 3 : SELECT THE FEASIBLE CYCLE TIME AND DETERMINE THE MINIMUM NUMBER OF WORK STATIONS
STEP 4 : PROCEED COLUMN BY COLUMN, FROM LEFT TO RIGHT AND ASSIGN WORK ELEMENTS TO THE STATION SUCH THAT – (i) THE WORK ELEMENT WITH THE LARGEST TIME IS CHOSEN FIRST (ii) THE SUM OF THE ELEMENTAL TIMES DOES NOT EXCEED THE CYCLE TIME (C) IF THE STATION TIME EXCEEDS TIME DUE TO INCLUSIONS OF A WORK ELEMENT, THEN SUCH AS ELEMENT IS ASSIGNED TO THE NEXT STATION.
STEP 5 : DELETE THE ASSIGNED WORK ELEMENTS AND REPEAT STEP 3 FOR THE REMAINING WORK ELEMENTS.
STEP 6 : REPEAT STEPS 4 TO 5 UNTIL ALL WORK ELEMENTS ARE ASSIGNED TO WORK STATIONS.
3. RANKED POSITIONAL WEIGHT TECHNIQUE
STEP 1 : CONSTRUCT THE PRECEDENCE DIAGRAM FOR THE WORK ELEMENTS INVOLVED STEP 2 : DETERMINE THE POSITIONAL WEIGHT FOR EACH WORK ELEMENT (A POSITIONALWEIGHT OF AN OPERATION REPRESENTS THE MAXIMUM TIME FROM THE BEGINNING OF WORK ELEMENT THROUGH THE REMAINDER OF THE NETWORK.)
STEP 3 : RANK WORK ELEMENTS ACCORDING TO THEIR POSITIONAL WEIGHTS IN STEP 2 BEGINNING WITH WORK ELEMENT WITH THE HIGHEST POSITIONAL WEIGHT DOWN THE ONE WITH THE SMALLEST POSITIONAL WEIGHT. STEP 4: CONSIDERING THE PRESEDENCE RELATIONSHIP, ASSIGN THE WORK ELEMENT WITH THE HIGHEST POSITIONAL WEIGHT TO THE FIRST STATION.
STEP 5 : IF ANY UNALLOCATED TIME REMAINS AFTER ASSIGNMENT OF WORK ELEMENT, ASSIGN THE NEXT SUCCEEDING RANKED WORK ELEMENTS TO THE STATION WITHOUT VIOLATING THE PRECEDENCE RELATIONSHIPS AND WITHOUT LETTING THE STATION TIME EXCEED THE CYCLE TIME. STEP 6 : REPEAT STEPS 4 & 5 UNTIL ALL WORK ELEMENTS ARE ASSIGNED TO THE WORK STATIONS.
doc_256172449.ppt