Process dsign and facility layout

Process Design and Facility Layout

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

DMA Kulasooriya

ISL- Certified Six Sigma Black Belt

Process Selection and System Design

Forecasting

Product and

service design

Capacity

planning

Facilities and

Equipment

Layout

Work

design

Process

selection

Technological

change


Introduction

• Make or Buy?

– Available capacity

– Expertise

– Quality Consideration

– The nature of demand

– Cost


Variety

◦ How much

Flexibility

◦ What degree

Volume ◦ Expected output

Process Selection


Process Types

• Job Shops

– Small runs

• Batch Processing

• Repetitive/Assembly

– Semicontinuous

• Continuous Processing

• Projects

– Nonroutine jobs


ProductVariety

High Moderate Low Very Low

Equipmentflexibility

High Moderate Low Very Low

LowVolume

ModerateVolume

HighVolume

Very highVolume

Job

Shop

Batch

Repetitive

assembly

Continuous

Flow

Variety, Flexibility, & Volume


Product-Process Matrix

Flexibility-Quality Dependability-Cost

Continuous

Flow

Assembly

Line

Batch

Job

Shop

Low

Volume

One of a

Kind

Multiple

Products,

Low

Volume

Few

Major

Products,

Higher

Volume

High

Volume,

High

Standard-

ization

Commercial

Printer

Heavy

Equipment

Automobile

Assembly

Sugar

Refinery

Flexibility-

Quality

Dependability

Cost


Automation: Machinery that has sensing and control devices that enables it to operate

Automation


Automation

• Computer-aided design and

manufacturing systems (CAD/CAM)

• Numerically controlled (NC) machines

• Robot

• Manufacturing cell

• Flexible manufacturing systems

• Computer-integrated manufacturing

(CIM)


Layout:

the arrangement of departments, work station, and equipment, with particular emphasis on movement of work (people, information or materials) through the system

Layout


Basic Layout Types

Product Layouts

Process Layouts

Fixed-Position

Combination Layouts


Basic Layout Types

Product Layout ((Assembly line) ◦ Arrange activities in a line according to the sequence of operations for a particular product or service. Layout that uses standardized processing operations to achieve smooth, rapid, high-volume flow

Process Layout (functional layout) ◦ Group similar activities together according to the process they perform. Eg. Drilling, lathe

Fixed Position Layout ◦ Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed ( ships, Air craft)


Requires substantial investments of money and effort

Involves long-term commitments

Has significant impact on cost and efficiency of short-term operations

Importance of Layout Decisions


The Need for Layout Decisions

Inefficient operations

For Example:

High Cost

Bottlenecks

Changes in the design

of products or services

The introduction of new

products or services

Accidents

Safety hazards

The Need for Layout Designs (Cont’d) Changes in

environmental

or other legal

requirements

Changes in volume of

output or mix of

products

Changes in methods

and equipment

Morale problems

Basic Layout Formats

Group Technology Layout

Just-in-Time Layouts

◦ May be assembly-line or

◦ Group Technology formats

Fixed Position Layout ◦ e.g. Shipbuilding

Part Family W Part Family X

Part Family Y Part Family Z


Cellular Layouts

Cellular Manufacturing

Group Technology

Flexible Manufacturing Systems


Cellular Layouts

Cellular Manufacturing ◦ Layout in which machines are grouped into a cell that can process items that have similar processing requirements

Group Technology ◦ The grouping into part families of items with similar design or manufacturing characteristics


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


Process Layout

Process Layout - work travels

to dedicated process centers

Milling

Assembly

& Test Grinding

Drilling Plating


Functional Layout

Gear

cutting

Mill Drill

Lathes

Grind

Heat

treat

Assembly

111

333

222

444

222

111

444

111 333 1111 2222

222

3333

111

444

111


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)



The Basic Block Company needs to produce 4000 boxes of

blocks per 40-hour week to meet upcoming holiday demand. The

process of making blocks can be broken down into six work

elements. The precedence and time requirements for each

element are as follows. Draw and label a precedence diagram for

the production process. Set up a balanced assembly line and

calculate the efficiency of the line

WORK PERFORMANCE

ELEMENT PRECEDENCE TIME (MIN)

A — 0.10

B A 0.40

C A 0.50

D — 0.20

E C, D 0.60

F B, E 0.40


Quick Start Technologies (QST) helps companies design

facility layouts. One of its clients is building five new assembly

plants across the continental United States. QST will design

the assembly-line layout and ship the layout instructions,

along with the appropriate machinery to each new locale. Use

the precedence and time requirements.

given below to design an assembly line that will produce a new

product every 12 minutes. Construct a precedence diagram,

group the tasks into workstations, determine the efficiency of

the line, and calculate the expected output for an eight-hour

day.


Task Precedence Time (mins)

A None 6

B A 2

C B 2

D A 1

E A 7

F A 5

G C 6

H D, E, F 5

I H 3

J G 5

K I, J 4

Line Balancing Rules

Assign tasks in order of most following tasks.

Assign tasks in order of greatest positional weight.

Positional weight is the sum of each task’s time and the times of all following tasks.

Some Heuristic (intuitive) Rules:


Parallel Workstations

1 min. 2 min. 1 min. 1 min. 30/hr. 30/hr. 30/hr. 30/hr.

1 min.

1 min.

1 min. 1 min. 60/hr.

30/hr. 30/hr.

60/hr.

1 min.

30/hr.

30/hr.

Bottleneck

Parallel Workstations


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 and facility layout

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