assembly line balancing

What is Line Balancing ?? Assigning each task to a work within an assembly line in order to meet the required production rate and to achieve a minimum amount of idle time..  Line balan

ASSEMBLY LINE

BALANCING

MODUL 7

What is Line Balancing ??

 Assigning each task to a work within an

assembly line in order to meet the required production rate and to achieve a minimum amount of idle time

 Line balancing is the procedure in which

tasks along the assembly line are assigned

to work station so each line has

approximately same amount of work

Terms Defined

 Delay/idle time of a workstation: the

difference between the cycle time (CT) and the station time (ST)

 Cycle time (CT): the time between the

completion of 2 successive assemblies,

assumed constant for all assemblies for a given conveyor speed

Terms Defined (Cont.)

 Line efficiency (LE): the ratio of total station time to the cycle time multiplied by the number of workstations

 Balance Delay

 Balance Delay

 Work element: a part of the total work content in an assembly process

Terms Defined (Cont.)

 Smoothness index (SI): an index to indicate the relative smoothness of a given

assembly line balance A smoothness index

of zero indicates a perfect balance

 Workstation (WS): a location on the

assembly line where a work element or

elements are performed on the product

Precedence Constraint

 Precedence Constraint is a restriction on the order of execution of work elements

 There are two conditions taht usually

appear in assembling process:

1 There is no dependency of the components

in the works

2 If a component has been selected to be

assembled, then the sequence begins to assemble other components.

Precedence diagram

 Precedence diagram: a diagram that describes the ordering in which work elements should be

performed It shows that some jobs cannot be

performed unless their predecessors are

completed The layout of workstations along the assembly line depends on the precedence diagram

 Presedence diagram symbols:

 Symbol element

 Relationship between symbols

Precedence Diagram

Zoning Constraint

 Allocation of work elements at the work

station is also limited by zoning constraints

that preclude or require grouping of certain elements of the work on a particular

station

Line Balancing Methods

 Helgeson dan Birnie / Ranked Positional Weight (RPW)

 Kilbridge and Wester Heuristic (Region Approach)

 Largest Candidate Rule

Helgeson dan Birnie / Ranked

Positional Weight (RPW)

Step 1- Calculate the weight of the position of each work

elements.

Step 2- Sort the elements according to the weight of the

position of the largest to the smallest.

Step 3 -Calculate the cycle time.

 4 Place the working element with the greatest weight on all the workstations do not violate precedence relationships and time station does not exceed the cycle time.

 5 Repeat step 4 until all the elements are placed.

 6 After forming a work station consisting of its elements, then specify the value of efficient, balance delay, and its smoothest index.

Kilbridge and Wester Heuristic

(Region Approach)

 Create precedence diagram of the problems faced Separate work elements in the diagram in columns from right to left.

 2 Determine the cycle time (TC) of primes total time working elements, and specify the number of work stations.

 3 Place the work elements to work stations such that the total time working element does not exceed the cycle time Remove elements of work that has been placed on the list of work elements.

 4 When an element of work placement resulted in a total time of work elements exceeds the cycle time working elements are placed in the next work station.

 5 Repeat steps 3 and 4 until all work elements are placed.

 6 Determine the value of efficient, balance delay, and smoothness index

Largest Candidate Rule

 The basic principle is to combine the processes of sorting

operation on the basis of the largest processing time to the

smallest elements of the operating time

 Steps:

1 Starting from the top, select the element to be assigned to the first station, which meets the requirements of precedence and does not cause the total amount exceeds Tek on stretcher station Ts.

2 If there are no other elements that can be assigned without

exceeding Ts, then move on to the next station.

3 Repeat steps 1 and 2 for the other stations until the completion

of all elements assigned.

4 Determine the value of efficient, balance delay, its smoothness index.