1. Part Two
Design
Chapter 4
Process design

2. Process design Direct Operations management Design Develop Deliver
Supply network design
Layout
and flow
Process technology
People, jobs and organization
Product/service design
Figure 4.1 The design activities in operations management

3. Key operations questions
In Chapter 4 – Process design – Slack et al. identify the following key questions…
What is process design?
What objectives should process design have?
How does volume and variety affect process design?
How are processes designed in detail?
What are the effects of process variability?

4. 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.

5. Designing the product or service
The design of products/services and processes are interrelated and should be treated together
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
Figure 4.2 The design of products/services and processes are interrelated and should be treated together

6. The overlap of activities is greater in service design
Design of the product
Design of the process
Design of the service
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

7. Operations performance objective Typical process design objectives
The impact of performance objectives on design
Operations performance objective
Typical process design objectives
Quality
Provide appropriate resources, capable of achieving the specification of product of services
Error-free processing
Speed
Minimum throughput time
Output rate appropriate for demand
Dependability
Provide dependable process resources
Reliable process output timing and volume
Flexibility
Provide resources with an appropriate range of capabilities
Change easily between processing states (what, how or how much is being processed?)
Cost
Appropriate capacity to meet demand
Eliminate process waste in terms of,
excess capacity
excess process capability
in-process delays
in-process errors
inappropriate process inputs
Table 4.1 The impact of strategic performance objectives on process design objectives and performance

8. Operations performance objective Some benefits of good process design
The impact of performance objectives on design (Continued)
Operations performance objective
Some benefits of good process design
Quality
Products and service produced ‘on-specification’
Less recycling and wasted effort within the process
Speed
Short customer waiting time
Low in-process inventory
Dependability
On-time deliveries of products and services
Less disruption, confusion and rescheduling within the process
Flexibility
Ability to process a wide range of products and services
Low cost/fast product and service change
Low cost/fast volume and timing changes
Ability to cope with unexpected events (e.g. supply or a processing failure)
Cost
Low processing costs
Low resource costs (capital costs)
Low delay/inventory costs (working capital costs)
Table 4.1 The impact of strategic performance objectives on process design objectives and performance (Continued)

9. Environmentally sensitive process design
Some fundamental issues:
The sources of inputs to a product or service. (Will they damage rainforests? use up scarce minerals? exploit the poor or use child labour?)
Quantities and sources of energy consumed in the process. (Do plastic beverage bottles use more energy than glass ones? Should waste heat be recovered and used in fish farming?)
The amounts and type of waste material that are created in the manufacturing processes. (Can this waste be recycled efficiently, or must it be burnt or buried in landfill sites?)
The life of the product itself. If a product has a long useful life will it consume fewer resources than a short-life product?
The end-of-life of the product. (Will the redundant product be difficult to dispose of in an environmentally friendly way?)

10. 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.

11. Manufacturing process types
Project
Diverse/complex
Repeated/divided
Intermittent
Continuous
Process tasks
Process flow
High
Jobbing
Batch
Variety
Mass
Contin-uous
Low
Low
Volume
High
Figure 4.3 Different process types imply different volume–variety characteristics for the process

12. Service process types Process tasks Process flow High
Diverse/ complex
Repeated/ divided
Intermittent
Continuous
Process tasks
Process flow
High
Professional service
Service shop
Variety
Mass service
Low
Low
Volume
High
Figure 4.3 Different process types imply different volume–variety characteristics for the process (Continued)

13. Project processes
One-off, complex, large scale, high work content ‘products’.
Specially made, ‘every one customized’.
Defined start and finish: time, quality and cost objectives.
Many different skills have to be coordinated.

14. Jobbing processes
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, complete whole product.

15. Batch processes 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.

16. Mass (Line) processes Higher volumes than batch.
Standard, repeat products (‘runners’).
Low and/or narrow skills.
No set-ups or almost instantaneous ones.

17. Continuous processes
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.

18. Professional service High levels of customer (client) contact.
Clients spend a considerable time in the service process.
High levels of customization with service processes being highly adaptable.
Contact staff are given high levels of discretion in servicing customers.
People-based rather than equipment-based.

19. Service shops Medium levels of volumes of customers.
Medium, or mixed, levels of customer contact.
Medium, or mixed, levels of customization.
Medium, or mixed, levels of staff discretion.

20. Mass service High levels of volumes of customers.
Low to medium levels of customer contact.
Low, or mixed, levels of customization.
Low, or mixed, levels of staff discretion.

21. Deviating from the ‘natural’ diagonal on the product-process matrix has consequences for cost and flexibility
Manufacturing operations process types
Service operations process types
High variety
Low volume
Low variety
High volume
Product/service characteristics
Project
Jobbing
Batch
Mass
Continuous
Professional
service
Service
shop
More process flexibility than is needed, so high cost
Less process flexibility than is needed, so high cost
The ‘natural’ line of fit of process to volume/variety characteristics
Figure 4.4 Deviating from the ‘natural’ diagonal on the product–process matrix has consequences for cost and flexibility Source: Based on Hayes and Wheelwright 9

22. Product-process matrix – water meter example
High variety
Low volume
Low variety
High volume
Product/service characteristics
Original service with appropriate process characteristics
New service, old process, so excess process flexibility and high cost A B
Process characteristics
New service with new process having appropriate process characteristics C
The ‘natural’ diagonal or ‘line of fit’
Figure 4.5 A product–process matrix with process positions from the water meter example

23. Process mapping symbols
Delay (a wait, e.g. for materials)
Operation (an activity that directly adds value)
Inspection (a check of some sort)
Transport (a movement of some thing)
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 process

24. Process map – ‘enquire to delivery’ at stage lighting firm
Customer request
Check availability file
Supply from stock ?
Customer wants search ?
Search
Find supplier ?
Call customer
Reserve on availability file
Kit wagon to store
Assemble kit
Check equipment
Needs attention ?
Repair
Pack for delivery
Deliver to customer
Send customer guide
Confirm to supplier
Stored equip. Y N
Kit to workshop
Supplier’s equipment to store
Supplier
Figure 4.7 Process map for ‘enquire to delivery’ process at stage lighting operation

25. ‘Supply and install’ process mapped at three levels
The operation of supplying and installing lighting equipment
The outline process of supplying and installing lighting equipment
‘Enquire to delivery’
‘Collect and check’
‘Install and test’
File failure note
Inform customer N
Rectify in time ? Y
Rectify N
To customer site
Routine control check
Safety check Y
Pass check ? Y
Job sign-off
Return to base
Compliant ?
Install N
The detailed process of ‘Install and test’ activity Y
Rectify in time ? N
Call for help
Rectify
Figure 4.8 The ‘supply and install’ operations process mapped at three levels

26. ‘Collect and check’ process – levels of process visibility
Very high visibility
Check it worked ok
Call customer to agree terms
Worked ok ?
Agree report N Y
Line of interaction
Take out equipment
High visibility
Medium visibility
To site
To base
Line of visibility
Amend usage records
Back office – low visibility
Prepare report N
Check and clean equipment
Did it work ok ?
Equipment to store Y
Figure 4.9 The ‘collect and check’ process mapped to show different levels of process visibility

27. Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)
Little’s law (a really quite useful law)
Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)
Cycle time = 2 mins
WIP = 10
Throughput time = ?
Throughput time = 10 × 2 mins
Throughput time = 20 mins

28. Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)
Little’s law (a really quite useful law) (Continued)
Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)
Need to mark 500 exam scripts in 5 days (working 7 hours a day). Takes 1 hour to mark a script. How many markers are needed?
Throughput time = 5 days × 7 hours = 35 hours
35 hours = 500 scripts × Cycle times
Cycle time = hours
500 scripts
= 0.07 hours
Number of markers = Work content = 1 hour =
Cycle time
0.07

29. Throughput efficiency
Throughput efficiency is the work content of whatever is being processed as a percentage of its throughput time.
Throughput efficiency =
Work content
Throughput time
× 100

30. X X X X X X X High utilization but long throughput times
5-15 mins
Arrival frequency (demand)
Processing time
Utilization = <100% % Q = >0
Arrival frequency (demand) X
Utilization = 100 % Q = infinity
9 mins X
Utilization = 50 % Q = 0
20 mins X
10 mins
Utilization = 100 % Q = 0
30 mins
10 mins
Processing time
Utilization = % Q = 0
High
High utilization but long throughput times
Low utilization but short throughput times
Reduce process variability
Process throughput time
(or inventory)
Average length of queue X X
Low X
20%
40%
60%
80%
100%
Capacity utilization
Figure The relationship between process utilization and number of items waiting to be processed for constant, and variable, arrival and process times

31. Process utilization, waiting time and variability
High utilization but long waiting time
Average number of units waiting to be processed
Decreasing variability
Average number of units waiting to be processed
Reduction in process variability X
Short waiting time but low utilization Z Y 10 20 30 40 50 60 70 80 90
100 10 20 30 40 50 60 70 80 90
100
Utilization
Utilization
(a) Decreasing variability allows higher utilization without long waiting times
(b) Managing process capacity and/or variability
Figure The relationship between process utilization and number of items waiting to be processed for variable arrival and activity times

32. Chapter 4 ‘end-of-chapter’ case
Slide deck for Action Response Case
Source: Shutterstock/ Yuri Acurs

33. Cycle time = time between unit outputs
Some process metrics
Activity A
Activity C
Activity B
Activity D
Activity E
Activity F
Activity G
The individual activities that make up the process.
The sequence of the activities and the flow between them.
Unit time A
Unit time B
Unit time C
Unit time E
Unit time D
Unit time G
Unit time F
The time required for each activity (Unit time A, B, C, etc.).
The ‘work in progress’ (wip) within the process.
Cycle time = time between unit outputs
Throughput time
The ‘work content’ of the whole job (Unit time A + Unit time B + Unit time C, etc.).
The number of staff allocated to the process.

34. Action response TASK Read the Action Response case and…
Map the application processes
Identify the strengths and weaknesses of their processes
Help to suggest possible improvements

35. ARAPU process map 300/week Receipt clerks (4) (10 mins) 100/week
Coding clerks
(5)
(20 mins)
Secretaries
(3)
Assessors
(7)
(100 take 10 mins)
(300 take 60 mins)
Committee
Payment clerks
Decline clerks
(4)
(3)
(50 mins)
(30 mins)
Dispatch
(2)
(10 mins)

36. ARAPU objectives?
Quality?
Speed?
Dependability?
Flexibility?
Cost?

37. Cycle time, throughput time and work-in-progress
Calculating the required cycle time
Forecast demands during the period (A)
Availability of productive time (B)
Cycle time (C = B/A)
Deciding how many staff are needed
Work content of the task (D)
Cycle time required (C)
Number of staff (D/C)
100
480 mins
4.8 mins
55 mins
4.8 mins
11.46 (12)

38. For action response… 300 2,100 mins 7 mins 127.5 mins 7 mins Actual=25
Calculating the required cycle time
Forecast demands during the period (A)
Availability of productive time (B)
Cycle time (C = B/A)
Deciding how many staff are needed
Work content of the task (D)
Cycle time required (C)
Number of staff (D/C)
300
2,100 mins
7 mins
127.5 mins
7 mins
Actual=25
18.21 (19)

39. Cycle time, throughput time and work-in-progress
Little’s law (a really quite useful law)
Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)
Cycle time = 2 mins
WIP = 10
Throughput time = ?
Throughput time = 10 × 2 mins
Throughput time = 20 mins

40. Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)
For action response...
Little’s law
Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)
Cycle time = 7 mins
Cycle time = ?
WIP = ?
WIP = 2,000
Throughput time = ?
Throughput time = 2,000 × 7 mins
Throughput time = 14,000 mins
Throughput time = days

41. Balancing
An ideal balance where activities are allocated equally between stages
Cycle time = 12 mins
Cycle time = mins
Stage 2
Stage 1
Stage 1
Stage 2
Stage 3
Stage 4
Stage 3
Stage 4
Balancing waste = 5 mins per unit
Balancing waste =

42. Balancing (Continued)
Load = 400 × 10 = 4,000 mins/week
Load = 4,000/4 = 1,000 mins/person
300/week
Receipt clerks
(4)
(10 mins)
100/week
Coding clerks
Load = 400 × 20 = 8,000 mins/ week
Load = 8,000/5 = 1,600 mins/person
(5)
(20 mins)
Secretaries
(3)
ARAPU Process map
Load = 400 × 47.5 = 19,000 mins/week
Load = 19,000/7 = 2,714 mins/person
Assessors
(7)
(100 take 10 mins)
(300 take 60 mins)
Committee
Load = 150 × 50 = 7,500 mins/week
Load = 7,500/4 = 1,875 mins/person
Payment clerks
Decline clerks
Load = 150 × 30 = 4,500 mins / week
Load = 4,500/3 = 1,500 mins/person
(4)
(3)
(50 mins)
(30 mins)
Dispatch
(2)
Load = 300 × 10 = 3,000 mins/week
Load = 3,000/2 = 1,500 mins/person
(10 mins)

43. Value stream mapping TPT = Total processing time
TTT = Total throughput time
P/T = Processing time
Yield = quality conformance
C/O = Change-over time
Rel = Reliability
Resubmitted applications, approx. 100/week
Further information request, approx. 100/week
New applications, approx. 300/week average IN IN IN
Receive
Code
Assess
X 100%
Batched 2X per day
X 100%
Batched 2X per day
X 100%
FIFO
To Committee, batched every Thursday am
FIFO
Largest given priority
P/T = 10 min
Yield = 99%
C/O = 0 min
Rel = 95%
P/T = 20 min
Yield = 98%
C/O = 0 min
Rel = 97%
P/T = 10–60m
Yield = 99%
C/O = 0 min
Rel = 99%
10 min
20 min
47.5 min
Approx. 3 days
Approx. 5 days
Approx. 10 days

44. Value stream mapping (Continued)
TPT = Total processing time
TTT = Total throughput time
P/T = Processing time
Yield = quality conformance
C/O = Change-over time
Rel = Reliability IN
Pay
X 100%
FIFO?
Batched 1X per week
P/T = 50 min
Yield = 98%
C/O = 0 min
Rel = 97%
Batched 1X per day
New applications, approx. 300/week average IN IN
Committee
Dispatch
X 100%
As recom- mended by assessors
To applicants IN
Largest given priority
P/T = ?
Yield = 100%
C/O = ?
Rel = 100%
Batched 1X per week
P/T = 10 min
Yield = 99%
C/O = 0 min
Rel = 99%
Decline
X 100%
Batched 1X per day
FIFO?
P/T = 30 min
Yield = 98%
C/O = 0 min
Rel = 97%
150 min
50–30 min
10 min
TPT = min
3.5 days
Approx. 5 days
Approx. 6 days
TTT = 33.3 days