chapter 4 process design

Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007

Chapter 4

Process design

Source: Joe Schwarz, www.joyrides.com


Process design

Operations strategy

Design Improvement

Planning and control

Operations management

Process design

Supply network design

Layout and flow

Process technology

Job design

Product/service design


Nature and purpose of the design activity

Products, services and the processes which produce them all have to be designed

Decisions taken during the design of a product or service will have an impact on the decisions taken during the design of the process which produces those products or services, and vice versa


Products and services should be designed in such a way that they

can be created effectively

Designing the product or service

Processes should be designed so they can

create all products and services which

the operation is likely to introduce

Designing the process

Product / service design has an impact on the

process design and vice versa

Design of products / services and design of processes are interrelated and should be treated together


Design of the Service

Design of the Process

Design of the Product

Design of the Process

In most service operations the overlap between service

and process design is implicit in the nature of

service

In manufacturing operations overlapping the activities of product and process design

is beneficial


Delay (a wait, e.g. for materials)

Operation (an activity that directly adds value)

Inspection (a check of some sort)

Transport (a movement of something)

Storage (deliberate storage, as opposed to a delay)

Process mapping symbols derived from ‘Scientific

Management’

Decision (exercising discretion)

Process mapping symbols derived from Systems Analysis

Direction of flow

Input or output from the process

Activity

Beginning or end of the process


Designing processes

There are different ‘process types’

Process types are defined by the volume and variety of ‘items’ they process

Process types go by different names depending on whether they produce products or services


Hig

h

VolumeLow High

Var

iety

Project

Low

Manufacturing process types

Process tasks

Process flow

Diverse/ complex

Repeated/ divided

Intermittent

Continuous

Jobbing

Batch

Mass

Contin-uous


One-off, complex, large-scale ‘products’ with high work content

Specially made, every one ‘customized’

Defined start and finish: time, quality and cost objectives

Many different skills have to be coordinated

Project processes


A project process with a small part of the process map that would describe the whole process


Very small quantities: ‘one-offs’, or only a few required

Specially made: high variety, low repetition, ‘strangers’, every one ‘customized’

Skill requirements are usually very broad

Skilled jobber, or team, completes whole product

Jobbing processes


Preparing photolithography materials on a jobbing basis with a typical process map


Higher volumes and lower variety than for jobbing

Standard products, repeating demand. But can make specials

Specialized, narrower skills

Set-ups (changeovers) at each stage of production

Batch processes


A batch process in a kitchen together with an illustrative process map


Higher volumes than batch

Standard, repeat products (‘runners’)

No set-ups, or almost instantaneous ones

Low and/or narrow skills

Mass (line) processes


A mass process – a packing process


Extremely high volumes and low variety:often single product

Standard, repeat products (‘runners’)

Highly capital-intensive and automated

Few changeovers required

Difficult and expensive to start and stop the process

Continuous processes


Part of a continuous process and a typical process map


VolumeLow High

Var

iety

Low

Hig

h

Service process typesProcess

tasksProcess

flow

Diverse/ complex

Repeated/ divided

Intermittent

Continuous

Professional service

Service shop

Mass service


A professional service –Consultants planning how best to help their client


A service shop – This health club offers some varietywithin a standard set of facilities and processes


A mass service – This call centre can handlea very high volume of customer enquiries because it

standardizes its process

Source: Royal Bank of Scotland Group


Deviating from the ‘natural’ diagonal on the product–process matrix has consequences for cost and flexibility

None

None

Less process flexibility than is needed so

high cost

More process flexibility than is

needed so high cost

The ‘natural’ line of fit of process to volume/variety characteristics

Project

Jobbing

Batch

Mass

Continuous

Manufacturing operations

process types

Professionalservice

Serviceshop

Massservice

Service operations

process typesVariety

Volume


Deviating from the ‘natural’ diagonal on the product–process matrix has consequences for cost and flexibility

None

None

Variety

Volume

Old process

Old process,

new product

New process,

new product


Flow (layout), technology and job design are all influencedby process positioning

None

None

Variety

Volume

Machine tool maker

Custom furniture maker

Automobile factory

Petro- chemical refinery

Flow Technology Jobs

Unorganized

Predictable

Little / general

Specialist

Varied / high discretion

Routine / low discretion


Flow (layout), technology and job design are all influencedby process positioning

None

None

Variety

VolumeFlow Technology Jobs

Unorganized

Predictable

Little / general

Specialist

Varied / high discretion

Routine / low discretion

Customer service branch

Investment banking

Bank call centre

Credit card processing


Delay (a wait, e.g. for materials)

Operation (an activity that directly adds value)

Inspection (a check of some sort)

Transport (a movement of something)

Storage (deliberate storage, as opposed to a delay)

Process mapping symbols derived from ‘Scientific

Management’

Decision (exercising discretion)

Process mapping symbols derived from Systems Analysis

Direction of flow

Input or output from the process

Activity

Beginning or end of the process


Standard sandwich process

Raw materials

Assembly Stored sandwiches

Move to outlets

Stored sandwiches

Customer request

SellTake

payment

Customized sandwich – old process


Raw materials

Take payment

Customized sandwich – old process

Customer request

Assembly


The operation of making and selling customized sandwiches

Outline process of making and selling customized sandwiches

PrepareAssemble as

requiredTake

payment

Bread and base filling

Stored ‘bases’

Fillings

Assemble whole sandwich

Customer request

Use standard ‘base’?

Assemble from standard ‘base’

No

Yes

Detailed process of assembling customized

sandwiches

Sandwich materials and

customers

Customers ‘assembled’ to

sandwiches


Bread and base filling

Assembly of ‘sandwich

bases’

Assemble from standard ‘base’

Take payment

Assemble whole sandwich

Customer request

Use standard ‘base’?

No

Yes

Fillings

Stored ‘bases’

Customized sandwich – new process


Reports to batch control

Reports filed Payment voucher to keying

Confirm payment

Report arrives

Stamp and date report

Check expenses report

Wait for processingCheck reports and vouchers

Attach payment voucher

Collect retorts into batch

Batch control number

Batch to audit desk

Wait for batching

Copy of reports to filing

Description of activity

Totals

8

1

2

4

5

6

7

9

10

3

11

12

14

15

13

5 5 2 2 1

Send to accounts receivable

Reports to batch control

Reports filed

Confirm payment

Report arrives

Stamp and date report

Send cash to receipt desk

Wait for processing

Check expenses report

Wait for processing

Check employee record

Check advance payment

Send to account payable

Wait for processing

Attach payment voucher

Collect retorts into batch

Check against rules

Wait for processing

Batch control number

Check payment voucher

Log report

Batch to audit desk

Wait for batching

Batch of reports logged

Copy of reports to filing

Description of activity

Totals

8

1

2

4

5

6

7

9

10

3

18

11

12

14

15

16

17

19

20

13

26

2223

24

25

21

7 8 5 5 1

Payment voucher to keying

Flow process charts for processing expense reports at Intel before and after improving the process


Throughput (TH) = Work in process (WIP) × Cycle time (CT)

Little’s law (a really quite useful law)

Cycle time = 2 minutes

Throughput time = ?

WIP = 10

Throughput time = 10 × 2 minutes = 20 minutes


Throughput (TH) = Work in process (WIP) × Cycle time (CT)

Little’s law (a really quite useful law)

Throughput time = 5 days × 7 hours = 35 hours

500 exam scripts need to be marked in 5 days (working 7 hours a day).It takes 1 hour to mark a script. How many markers are needed?

35 hours = 500 scripts × Cycle time

Cycle time = 35 hours500 scripts

= 0.07 hours

Number of markers = Work content = 1 hour = 14.29Cycle time 0.07


Throughput efficiency = Work content

Throughput time × 100

Throughput efficiency is the work content of whatever is being processed as a percentage of its throughput time

Throughput efficiency


0 20% 40% 60% 80% 100%

Capacity utilization

Low

X

X

X

High utilization but long throughput times

Low utilization but short throughput times

Reduce process variability

High

10 mins

30 mins

Arrival frequency (demand)

Processing time

Utilization = 33.33 % Q = 0A

vera

ge

len

gth

of

qu

eue

X

Utilization = 50 % Q = 0

20 mins

X

10 mins

Utilization = 100 % Q = 0X

Utilization = 100 % Q = infinity

9 mins

X

5–15 mins

5–15 mins

Arrival frequency (demand)

Processing time

Utilization < 100% Q > 0

Pro

cess

th

rou

gh

pu

t ti

me

(or

inve

nto

ry)


10 20 30 40 50 60 70 80 90 1000Utilization

Ave

rage

num

ber

of u

nits

w

aitin

g to

be

proc

esse

d

Decreasing variability

10 20 30 40 50 60 70 80 90 1000Utilization

Ave

rage

num

ber

of u

nits

w

aitin

g to

be

proc

esse

d

X

Y Z

High utilization but long waiting

time

Reduction in process

variabilityShort waiting time but low

utilization

(a) Decreasing variability allows higher utilization without long waiting times

(b) Managing process capacity and/or variability

The relationship between process utilization and number of units waiting to be processed for variable arrival and

activity times


Key Terms Test

Throughput timeThe time for a unit to move through a process.

UtilizationThe ratio of the actual output from a process or facility to its

design capacity.

Life cycle analysisA technique that analyzes all the production inputs, the life

cycle use of a product and its final disposal in terms of total energy used and wastes emitted.


Key Terms Test

Process typesTerms that are used to describe a particular general approach to

managing processes. In manufacturing these are generally held to be project, jobbing, batch, mass and continuous processes; in services they are held to be professional services, service shops and mass services.

Project processesProcesses that deal with discrete, usually highly customized,

products.

Jobbing processesProcesses that deal with high variety and low volumes, although

there may be some repetition of flow and activities.


Key Terms TestBatch processesProcesses that treat batches of products together, and where

each batch has its own process route.

Continuous processesProcesses that are high volume and low variety; usually products

made on continuous processes are produced in an endless flow, such as petrochemicals or electricity.

Professional servicesService processes that are devoted to producing knowledge-

based or advice-based services, usually involving high customer contact and high customization. Examples include management consultants, lawyers, architects, etc.


Key Terms TestService shopsService processes that are positioned between professional

services and mass services, usually with medium levels of volume and customization.

Mass servicesService processes that have a high number of transactions, often

involving limited customization, for example mass transportation services, call centres, etc.

Product–process matrixA model derived by Hayes and Wheelwright that demonstrates the

natural fit between volume and variety of products and services produced by an operation on one hand, and the process type used to produce products and services on the other.


Key Terms TestProcess mappingDescribing processes in terms of how the activities within the

process relate to each other (may also be called process blueprinting or process analysis).

Process mapping symbolsThe symbols that are used to classify different types of activity,

usually derived either from scientific management or from information systems flowcharting.

High-level process mappingAn aggregated process map that shows broad activities rather

than detailed activities (sometimes called an outline process map).


Key Terms Test

Work contentThe total amount of work required to produce a unit of

output, usually measured in standard times.

Throughput timeThe time for a unit to move through a process.

Cycle timeThe average time between units of output emerging from a

process.


Key Terms Test

Work-in-process

The number of units within a process waiting to be processed further (also called work-in-progress).

Little’s Law

The mathematical relationship between throughput time, work-in-process and cycle time:

Throughput time = work-in-process × cycle time

chapter 4 process design

Documents

stuart chambers

robert johnston

edition nigel slack

packing process slack

product slack

services slack

process products

control slack