process dsign line balancing

Process Design and Facility Layout

6/28/2015 DMA Kulasooriya, NIBM (UCD -BSc-2011)

DMA Kulasooriya

ISL- Certified Six Sigma Black Belt

Cellular Layouts

Cellular Manufacturing

Group Technology

Flexible Manufacturing Systems


A Flow Line for Production or Service

Flow Shop or Assembly Line Work Flow

Raw

materials

or customer

Finished

item Station

2

Station

3

Station

4

Material

and/or

labor

Statio

n

1

Material

and/or

labor

Material

and/or

labor

Material

and/or

labor


A U-Shaped Production Line

1 2 3 4

5

6

7 8 9 10

In

Out

Workers


Cellular Manufacturing Layout

-1111 -1111

222222222 - 2222

As

se

mb

ly

3333333333 - 3333

44444444444444 - 4444

Lathe

Lathe

Mill

Mill

Mill

Mill

Drill

Drill

Drill

Heat

treat

Heat

treat

Heat

treat

Gear

cut

Gear

cut

Grind

Grind


Design Product Layouts: Line Balancing

Line Balancing is the process of

assigning tasks to workstations in such

a way that the workstations have

approximately equal time requirements.


Cycle Time

Cycle time is the maximum time

allowed at each workstation to

complete its set of tasks on a unit.


Line Balancing

Assembly line balancing operates under two constraints,

precedence requirements and cycle time restrictions’

Precedence requirements are expressed in the form of a

precedence diagram- network

Cycle time is calculated by dividing the time available for

production by the number of units to be produced – time

taken to completed item rolling off the assembly line.


Determine Maximum Output

Output capacity = OT

CT

OT operating time per day

D = Desired output rate

CT = cycle tim e = OT

D


Determine the Minimum Number of Workstations Required: Efficiency

s task timeof sum = t

CT Desired

t)( = N


Real fruit Snack are made from a mixture of dried fruits and packaged. To meet demand real fruit needs to produce 6000 fruit strips every 40-hour week. Design an assembly line with fewest number of workstations that will achieve the production quota without violating precedence constraints


Work Element Precedence Time (Min)

A Press out sheet of fruits

----- 0.1

B Cut into strips A 0.2

C Outline Fun Shapes A 0.4

D Roll up and package B,C 0.3

Total 1.0


Precedence Diagram

Precedence diagram: Tool used in line

balancing to display elemental tasks and

sequence requirements A Simple Precedence

Diagram

A B

C

D

0.1 min. 0.2 min.

0.4 min.

0.3 min.


Calculate the desired CT (Takt Time) TT = 40 h * 60 m/ h = 2400 6000 units 6000 = 0.4 minute


Calculate the theoretical minimum number of workstations

N = 0.1 + 0.2 + 0.3 + 0.4 = 1.0 = 2.5

0.4 0.4

N= 2.5 = 3 workstations


Assembly Line Balancing

Arrange tasks shown in the previous slide into workstations.

◦ Use a cycle time of 0.4 minute

◦ Assign tasks in order of the most number of followers


Work Station

Work Element

Remaining time

Remaining Elements

1 A 0.3 B C

B 0.1 C D

2 C 00 D

3 D 0.1 None


A B

C

D

0.1 min. 0.2 min.

0.4 min.

0.3 min.

Assembly line with three workstations


A B C D

Workstation -01 Workstation -02 Workstation -03

0.3 m 0.4 m 0.3 m

Assembly Line


Calculate Percent Idle Time

Percent idle time = Idle time per cycle

(N)(CT)

PIT = 0.2/ 3 (0.4) = 16.6 %


Determine the Efficiency

s task timeof sum = t

actual) (CTn

t)( = E

E = 0.1 +0.2+0.3+0.4 = 1.0/ 1.2 = 83.3%

3 (0.4)


Requirements:

◦ List of departments

◦ Projection of work flows

◦ Distance between locations

◦ Amount of money to be invested

◦ List of special considerations

Designing Process Layouts


process dsign line balancing

Business