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Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.1
10.1
Chapter 10
The nature of planning and control
Pearson Education Ltd. Jules Selmes
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.2
10.2
Design
Planning and control
Operations strategy
Improvement
Capacity planning and control
Capacity planning and control
The operation supplies... delivered products and
services
The market requires… products and services delivered to requested
time, quantity and quality
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.3
10.3
In Chapter 10 – The nature of planning and control – Slack et al. identify the following key questions:
•What is planning and control?
•How do supply demand affect planning and control?
•What are the activities of planning and control?
Key operations questions
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.4
10.4
•Planning is a formalization of what is intended to happen at some time in the future.
•A plan does not guarantee that an event will actually happen, it is a statement of intention.
•Although plans are based on expectations, during their implementation things do not always happen as
expected.
•Control is the process of coping with any changes that affect the plan. It may also mean that an ‘intervention’ will need to be made in the operation to bring it back ‘on track’.
Planning and control
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.5
10.5
Planning is deciding
Control is
what activities should take place in the operationwhen they should take place
what resources should be allocated to them
understanding what is actually happening in the operation
deciding whether there is a significant deviation from what should be happening
(if there is deviation) changing resources in order to affect the operation’s activities.
Planning and control (Continued)
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.6
10.6
PLANNING
CONTROL
Significance of planning and controlTi
me
horiz
onH
ours
/day
sD
ays/
wee
ks/m
onth
sM
onth
s/ye
ars Long-term planning and control
Uses aggregated demand forecasts
Determines resources in aggregated form
Objectives set in largely financial terms
Medium-term planning and controlUses partially disaggregated demand forecasts
Determines resources and contingencies
Objectives set in both financial and operations terms
Short-term planning and controlUses totally disaggregated forecasts or actual demandMakes interventions to resources to correct deviations from plansAd hoc consideration of operations objectives.
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.7
10.7 Dependent and independent demand
Dependent demande.g. input tyre store in automobile plant
Demand for tyres is governed by the number of automobiles planned
to be made
For every automobile that are planned to be made, five tyres will be
needed
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.8
10.8 Dependent and independent demand (Continued)
Demand for tyres is largely governed by
random factors.
ACE TYRES
Demand for tyres is governed by the type of car arriving, the fluctuations in the number of cars arriving and how
many tyres need replacing.
Independent demande.g. tyre-fitting service
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.9
10.9 P : D ratios
DP
Produce to stock
DP
Part produce to order
DP
Resource to order
Customer orders
Deliver to customer
Allow time for delivery
Produce product/service
Allow time for creation
Obtain resources
Allow time for resourcing
DP
Produce to order
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.10
10.10 P : D ratios (Continued)
Resource to order
Make to stock
Make to order
Dependent demand
Independent demand
Each product or service (large) compared with total capacity of the operation
Each product or service (small) compared with total capacity of the operation
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.11
10.11
Scheduling Loading
SequencingMonitoring and control
When to do things?
In what order to do
things?
How much to do?
Are activities going to plan?
The activities of planning and control
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.12
10.12
Quality losses Slow
running equipment
Equipment ‘idling’ ‘Breakdown’
failure
Set-up and changeovers
Not worked (unplanned)
Valuable operating time
Maximum available time
Loading – The reduction of time available for ‘valuableoperating time’
Not worked (planned)
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.13
10.13
Finite and infinite loading of jobs on three work centres A, B and C. Finite loading limits the loading on each centre to their capacities, even if it means that jobs will be late. Infinite loading allows the loading on each centre to exceed their capacities to ensure that jobs will not be late.
12
34
56
0
Work centre Work centreA B C A B C
Finite loading Infinite loading
Weeks
Finite and infinite loading
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.14
10.14
In Accident and Emergency departments, patients arrive at random. Medical staff must rapidly devise a schedule. Patients with serious illness need urgent attention. Less urgent cases will have to wait. Routine non-urgent cases will have the lowest priority of all.
The hospital triage system
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.15
10.15 Triage in the police
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.16
10.16
Process stage
Week 12
Week 13
Week 14
Week 15
Week 16
Week 17
Week 18
Job A Job B Job C Job D Job E
Job A Job BJob Y Job X
Job A Job BJob Z Job XJob Y
Job A Job BJob X Job C
Gantt chart showing the schedule for jobs at eachprocess stage
Initial spec
Pre-coding
Coding
Compact. check
Final test
Job A Job BJob W Job C Job D
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.17
10.17
JOB Mon 5
Tue6
Wed 7 Thur 8
Fri 9
Mon 12
Tue 13
Table
Shelves
Kitchen units
Bed
Actual progressTime now
V
V
Gantt chart showing the schedule for individualjobs over time
Scheduled activity time
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.18
10.18
JOB Mon 5
Tue6
Wed 7 Thur 8
Fri 9
Mon 12
Tue 13
Wood preparation
Assembly
Finishing
Paint
Scheduled activity time Actual progress
T
B
B T
S K
S S S
K
KTS
B T
Non-productive timeV
V
Time now
Gantt chart by activity
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.19
10.19 Pull and push philosophies of planning and control
Push control
Work centre
Work centre
Work centre
Work centre
Instruction on what to make and where to
send it
DEMAND
FORECAST
OR
CENTRAL OPERATIONS, PLANNING AND CONTROL SYSTEM
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.20
10.20
Pull control
Work centre DEMAND
Pull and push philosophies of planning and control (Continued)
Work centre
Work centre
Work centre
Request Request Request Request
Delivery Delivery Delivery Delivery
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.21
10.21 Pull and push philosophies of planning and control (Continued)
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.22
10.22
Shift allocation for the technical ‘hot line’ (a) on a daily basis (b) on a weekly basis
(a)Shift pattern (24-hour clock)
Peter
Jo
Walter
Jo
Marie Claire Jo
04:00 08:00 12:00 16:00 20:00
Peter X X X X O O X Marie X X X X X O O Claire X X X X O O X Walter O X X X X X O
Jo O X X X X X O
Mon Tue Wed Thu Fri Sat Sun
Number of staff required
3 5 5 5 3 2 2
(b)
X OFull day Day off
Shift allocation
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.23
10.23
Operation or processInput Output
Compare / replan
InterventionPlans
A simple model of control
Monitor
Slack, Chambers and Johnston, Operations Management, 6th Edition,© Nigel Slack, Stuart Chambers, and Robert Johnston 201010.24
10.24 The drum, buffer, rope, concept
Stage or process
B
Stage or process
A
Stage or process
D
Stage or process
E
Buffer of inventory
Stage or process
C
Bottleneck drum sets the beat
Communication rope controls prior activities