03- process analysis
TRANSCRIPT
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OPM 1 Term 2, B2014-16, Oct-Dec 2014 Session 03 Process Analysis
Process Analysis
OPERATIONS MANAGEMENT -1
Term 2, B2014-16, Oct-Dec 2014
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OPM 1 Term 2, B2014-16, Oct-Dec 2014 Session 03 Process Analysis
West
converts iron ores into iron briquettes to supply steel
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OPM 1 Term 2, B2014-16, Oct-Dec 2014 Session 03 Process Analysis
~ 160 m
IronOreFines
CFBPreheater
InclinedBucket Elevator
1st StageCFB Reactor
2nd StageFB Reactor
HBI Produc
ProcessGas
HeatExchanger Process GasCompressor
Fired Gas Heaters
ElectricalSubstation&ControlRoom
Engineering drawing
To Create a Process Flow Chart (Diagram)
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OPM 1 Term 2, B2014-16, Oct-Dec 2014 Session 03 Process Analysis
Elements of a Process
Inventory / Buffers
Do NOT have a capacity; however,
there might be a limited number of
flow units that can be put in this
inventory space at any moment of time
Multiple flow unit types possible
Arrows
Indicate the flow of the flow unit
Multiple flow unit types possible
Activities
Carried out by resources
Add value and are required
for completion of the flow unit
May or may not carry inventory Have a capacity (maximum number
of flow units that can flow through
the activity within a unit of time)
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Pre-Heater
Pile of Iron ore fines
Process flow diagram, first step
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LockHoppers
1st Reactor 2ndPre-Heater
Pile of Iron ore fines
Process flow diagram, to be continued
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FlaHe
DischargeBriquetting
Lock
Hoppers1st Reactor 2nd RPre-Heater
Pile of Iron ore fines
Finished Goods
Completed process flow Process flow di
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Completed PFD for the Circored process
Pile of Iron
ore fines
Pre-Heater
Bri
tinFlash
heater
Dis-
charge
Fini
goo
Lock
Hoppers1st
Reactor
2nd
Reactor
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FlasHeaDischargeBriquetting
LockHoppers
1st Reactor 2ndRePre-Heater
Pile of Iron ore fines
Finished Goods
7.5% Outflow 15% Outflow 1
FlasHeaBriquetting
LockHoppers
1st 2ndPre-Heater
Pile of Iron ore fines
Finished Goods
Process flow diagram accounting for mass
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Session 03 Process Analysis
Process Concepts
Important
Process capacity
Flow rate
Cycle Time
Manufacturing Lead Time (MLT) /Throughput T Bottleneck
Process utilization and capacity utilization
Workload and implied utilization
Additional
Lot Size/Batch Size
Setup time Run time
Waiting time
Idle time
Buffer
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Session 03 Process Analysis
Bottleneck and process capacity Capacity: Number (amount) of units that can be processed pe
Each briquetting machine has a capacity of 55 tons per hour
Overall capacity of a sequence of processes is determined by
process, i.e. the resource with the smallest capacity.
Process capacity=Min{Capacity of Res 1, ., Capacity of Res
Incorporating available input rate and demand rate,
Throughput=Min{Input rate, Process capacity, Demand rate
Demand
InputBottleneckCapacity
Excesscapacity
Flow Rate
Demand
InputBottleneckCapacity
Excesscapacity
Flow Rate
Demand constrained
Flow Rate Flow Rate
Supply constrained
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Session 03 Process Analysis
Capacity Related Terminology
Setup time : thetime that a part
spends waiting for aresource to be set
up to work on thissame part
Process time/runtime is the timethat the part is
being processed
Queue titime th
waits for while the
is bussometh
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Time Components of Production Cycle (C
Wait time is the time that apart waits not for a resourcebut for another part so that
they can be assembledtogether
Idle time is the unuthat represents thtime less the sum
setup time, processqueue time, and w
i d i f
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Time to Produce a Certain Amount of Su
Assuming the process is already producing output.
How long does it take for the Trininad plant to prod10,000 tons?
A restaurant has 40 tables. Average flow time = 60 m
long is the wait time if you are sixth on the waiting l
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Throughput Time = Work-in-Process /Throughput rate
Operations management (OM) covers a large arena of practice.
Littles Law is discussed in several current OM texts, including Hopp a(2000), Cachon and Terwiesch (2004).
Queuing theory and OM generally use different notations for Littles Law
and so we introduce that issue first. In a desire to get close to people wh
using LL to support decision making,
Littles Law
Average Inventory = Average Flow Rate X Average Flow Tim
( Cachon and Terweiesch
( Hopp amd Spearman, 2000
Li l L
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Littles Law
7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00
Cumulative In-flow and Out-flow
11
10
98
7
6
5
4
3
2
1
0
Flow Time
Inventory
Inventory=Cumulative Inflow Cumulative Outflow
Cumulative
Inflow
Cumulative
Outflow
Patients
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The process capacity of Circored plant in Trini
Capacities
Preheater 120 tons/hour
Lock Hoppers 110 tons/hour
1st (cfb) Reactor 112 tons/hour. Processes 28 tons every 15 minutes
2nd (fb) Reactor 100 tons/hour. Processes 400 tons every 4 hours
Flash heater 135 tons/hour
Discharge 118 tons/hour
Briquetting 165 tons/hour
Pre-
Heater DischaFlash
heater
Lock
Hoppers 1st (cfb) Reactor
2nd (fb)
Reactor
Process Capac
= min{120,110,112,100,
= 100 tons/ho
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The cycle time of circored plant in Trinidad
Cycle time: Amount of time taken to process 1 unit in a repetitive
Since different units can be processed in parallel, cycle time is not the flow tim
Cycle time (designed) = 1 / Process Capacity
How long does it take to process 1 ton of iron ore?
Since 1 hour is required for 100 tons, 1/100 hour suffices for 1 ton.
That is, the cycle time is 0.01 hour = 0.6 min = 36 seconds
Every 36 seconds 1 ton of iron briquette is completed.
Pre-
Heater DischaFlash
heater
Lock
Hoppers 1st (cfb) Reactor
2nd (fb)
Reactor
P tili ti d C it tili ti
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OPM 1 Term 2, B2014-16, Oct-Dec 2014 Session 03 Process Analysis
Process utilization and Capacity utilizatio
The objective of most businesses is to increase profi
increase utilization.
A service process should not pursue 100% utilization
Utili ation of limited demand
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Utilization of limited demand Assume the demand is only 657,000 tons
Design capacity = (100 tons/hr X 24 hours/day X 365 days/ yr)
tons
The bottleneck is the resource with the highest utilization.
Utilization Profile
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Preheater LockHoppers
CFB StationaryReactor
Flashheater
Pressurelet-downsystem
Briquma
Imbalance relativeTo bottleneck
Mismatch between demand andsupply at the process level
Preheater LockHoppers
CFB StationaryReactor
Flashheater
Pressurelet-downsystem
Briquma
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Imbalance relativeTo bottleneck
Mismatch between demand andsupply at the process level
Bottleneck
Utilization
Utilization Profile
Workload and implied utilization
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Workload and implied utilization
Utilization only carries information about excess ca
Implied utilization captures the mismatch when the
exceeds the capacity.
The utilization with demand of 1 095 000
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The utilization with demand of 1,095,000
Bottleneck
Implied (requested) Utilization of a resource = Demand / Capacity
Preheater LockHoppers
CFB FB FlashHeater
Briquett0%
50%
75%
100%
Utilization
Discharge
125%
STEPS FOR BASIC PROCESS ANALYSIS WITH ON
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STEPS FOR BASIC PROCESS ANALYSIS WITH ON
OF FLOW UNIT
Find the capacity of everyresource, if there are
multiple resourcesperforming the same
activity add their capacitiestogether.
The resource with thelowest capacity is called the
bottleneck. Its capacitydetermines the capacity ofthe entire process (Process
Capacity).
The flow on Flow(Availab
Pro
We find the Utilization oSimilarly we find the utilization of eachresource as Flow rate
Different units flowing in the same syste
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File
Contact faculty/
other persons
Contact prior
employers
Benchmark
grades
Confirmation
letter
Internship
Staff
Consulting
File
Contact faculty/
other persons
Contact prior
employers
Benchmark
grades
Confirmation
letter
Different units flowing in the same syste Outsourcing business processes is common
Billing, Recruiting, Maintenance, Customer call centers, etc
The company which handles the outsourced process is likely to deal w
kinds of units
Case in point: A company that provides resume validation service:
Demand is 180 applications per day ( 30 for consulting, 110 for staff and remaining f
STEPS FOR BASIC PROCESS ANALYSIS WITH M
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OPM 1 Term 2, B2014-16, Oct-Dec 2014 Session 03 Process Analysis
STEPS FOR BASIC PROCESS ANALYSIS WITH M
TYPES OF FLOW UNITS1. For each resource, compute the number of minutes that the resource can produce; this is 6
Number of resources within the resource pool.
2. Create a process flow diagram, indicating how the flow units go through the process; use m
indicate the flow of the different flow units.
3. Create a table indicating how much workload each flow unit is consuming at each resource
The rows of the table correspond to the resources in the process.
The columns of the table correspond to the different types of flow units.
Each cell of the table should contain one of the following:
1. If flow unit does not visit the corresponding resource, ;
2. Otherwise, demand per hour of the corresponding flow unit activity time.4. Add up the workload of each resource across all flow units.
5. Compute the implied utilization of each resource as
Implied utilization = Result of Step 3
Result of Step 1
The resource with the highest implied utilization is the bottleneck.
An application as a unit
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An application as a unit
Activity
Time (min)
Per applct
Number
of workers
Available
Capacity
Applct/hr
Consulting
Workload
Per hour
Staff
Workload
Per hour
Intern
Workload
Per hour
T
File 3 1 20 3 11 4
Contact Persons 20 2 6 3 0 0
Contact
Employers
15 3 12 3 11 0
Benchmark
Grades
8 2 15 0 0 4
Confirmation
Letter
2 1 30 3 11 4
Demand per hour for validation: 3 for consulting; 11 for staff; 4 for inter
Using One minute of work as the flow unit to find the
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g
Activity
Time (min)
Per applct
Number
of workers
Available
Capacity
Consulting
Workload
Minutes Per
hour
Staff
Workload
Minutes Per
hour
Intern
Workload
Minutes Per
hour
File 3 1 60 3 X 3 11 X 3 4 X 3
Contact Persons 20 2 120 3 X 20 0 0
Contact
Employers
15 3 180 3 X 15 11 X15 0
Benchmark
Grades
8 2 120 0 0 4 X 8
Confirmation
Letter
2 1 60 3 X 2 11 4 X 2
Demand per hour for validation: 3 for consulting; 11 for staff; 4 for inter
A li ti it
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An application as a unit
What is the minimum number of people to hire simplied utilization of contact employers is below 100%
What happens to implied utilizations when staff ap
decrease to 8 per hour? Compute the new utilization
Summary of process analysis
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Compute the
Capacity for
each of the
Resources
Use demand to
compute the
implied utilization
levels
Identify the
Bottleneck
Prepare a
Process Flow
Diagram
Use different
Colors to mark
Flow units
Note that capacity
levels may differ
depending on
product type
Compute the work-
load across all
product types
Step with highest
implied utilizationExtensions required
for working with
multiple flow units
Extensions required
for working with
multiple flow units
Compute the
Capacity for
each of the
Resources
Use demand to
compute the
implied utilization
levels
Identify the
Bottleneck
Prepare a
Process Flow
Diagram
Compute the
Capacity for
each of the
Resources
Use demand to
compute the
implied utilization
levels
Identify the
Bottleneck
Prepare a
Process Flow
Diagram
Use different
Colors to mark
Flow units
Note that capacity
levels may differ
depending on
product type
Compute the work-
load across all
product types
Step with highest
implied utilization
Summary of process analysis
World class enterprises excel at the speedy and flexible integthe business processes.
Finding the bottleneck allows us to compute a variety of perf
measures.
You Can't Manage What You Don't Measure