Transcript Document

Process Analysis I
Operations -- Prof. Juran
Outline
• Process Analysis Defined
• Key Terms and Metrics
• Process Flowcharting
• Gantt Chart
• Example: Milford Physicians
Operations -- Prof. Juran
Process Analysis
A set of concepts, tools, and metrics for
describing, planning, controlling
managing, and improving processes.
A process is any part of an organization
that transforms inputs into outputs,
preferably adding value.
Operations -- Prof. Juran
Process Layout
• Process Layout
– Traditional Approach
– Aimed at Economies of Scale and Specialization
• Product Layout
– Basis for Cellular Manufacturing, Applied in some
services
– More customer focused?
– Behavioral benefits among workers?
Operations -- Prof. Juran
Other Types of Processes
• Make-to-order
– Only activated in response to an actual order
– Both work-in-process and finished goods
inventory kept to a minimum
• Make-to-stock
– Process activated to meet expected or forecast
demand
– Customer orders are served from target stocking
level
Operations -- Prof. Juran
Types of Processes
Single-stage Process
Stage 1
Multi-stage Process
Stage 1
Operations -- Prof. Juran
Stage 2
Stage 3
Process Analysis Terms
• Level of Analysis: The scope of our study; a single
machine, an assembly line, a factory, etc.
• Cycle Time: The average time between
completions of successive units
– Typically used at the lower levels of analysis
Operations -- Prof. Juran
Process Analysis Terms
• Utilization: The ratio of the time that a resource is
actually activated relative to the time that it is
available for use
• Flow Time: The time it takes for a single customer’s
order to proceed through the process from start to
finish. Sometimes called Throughput Time
• Throughput: The volume of production passing
through the process over some time period
– Typically used at the higher levels of analysis
Operations -- Prof. Juran
Process Analysis Terms
• Bottleneck
– Occurs when the limited capacity of a process
causes work to pile up or become unevenly
distributed in the flow of a process
– If an employee works too slow in a multi-stage
process, work will begin to pile up in front of
that employee. In this is case the employee
represents the limited capacity causing the
bottleneck.
• Pacing
– Refers to the fixed timing of the movement of
items through the process
Operations -- Prof. Juran
Process Analysis Terms
• Blocking
– Occurs when the activities in a stage must stop because
there is no place to deposit the item just completed
– If there is no room for an employee to place a unit of
work down, the employee will hold on to it not able to
continue working on the next unit
• Starving
– Occurs when the activities in a stage must stop because
there is no work
– If an employee is waiting at a work station and no work
is coming to the employee to process, the employee will
remain idle until the next unit of work comes
Operations -- Prof. Juran
Process Analysis Terms
A buffer refers to a storage area between
stages where the output of a stage is placed
prior to being used in a downstream stage
Bottlenecks, buffers, blocking, and starving
are key concepts in Just-in-Time systems,
which we will study later in the course
Operations -- Prof. Juran
Types of Processes (Continued)
Multi-stage Process with Buffer
Buffer
Stage 1
Operations -- Prof. Juran
Stage 2
Process Performance Metrics
• Operation time = Setup time + Run time
• Velocity = Throughput time
Value-added time
• Throughput rate =
1
.
Cycle time
Operations -- Prof. Juran
Process Performance Metrics
• Efficiency = Actual output
Standard Output
• Productivity = Output
Input
• Utilization = Time Activated
Time Available
Operations -- Prof. Juran
Cycle Time Example
Suppose you had to produce 600 units in 80 hours to
meet the demand requirements of a product. What is
the cycle time to meet this demand requirement?
Answer: There are 4,800 minutes (60 minutes/hour x
80 hours) in 80 hours. So the average time between
completions would have to be:
Cycle time = 4,800/600 units = 8 minutes.
Operations -- Prof. Juran
Process Improvement
• Flow Time Reduction
– Perform activities in parallel
– Change the sequence of activities
– Reduce interruptions
• Elimination of Non-Value-Added Steps
• Quality Improvement
Operations -- Prof. Juran
Process Flow Diagram
• A process flow diagram (a.k.a. flow chart) is
a graphical tool for describing the major
elements of a process
• The elements can include tasks or
operations, flows of materials or customers,
decision points, and storage areas or queues
• It is an ideal methodology by which to begin
analyzing a process
Operations -- Prof. Juran
Flowchart Symbols
Tasks or operations
Decision Points
Operations -- Prof. Juran
Examples: Giving an
admission ticket to a
customer, installing a
engine in a car, etc.
Examples: How much
change should be
given to a customer,
which wrench should
be used, etc.
Storage areas or
queues
Examples: Sheds, lines
of people waiting for a
service, etc.
Flows of
materials or
customers
Examples: Customers
moving to a seat,
mechanic getting a
tool, etc.
Operations -- Prof. Juran
Example: Flowchart of Student Going
to School
Go to
school
today?
No
Goof
off
Operations -- Prof. Juran
Yes
Drive to
school
Walk to
class
Man gets angry
Flow Chart of a Relationship
The man and the
woman agree to
have a date
Woman changes her mind
At the end of the date,
the man makes
sexual advances
No sex
Man nags about the
reasons why the woman
doesn’t want to have sex
Woman is more
relaxed this time
No sex for a long time
Man tries again;
Asks for a second date
Man guesses that the time is
right and approaches the woman
sexually
Woman starts to get tired
Woman suggests making
dinner together
Man trips on the edge of the carpet
on purpose to show the
woman how vulnerable he is
Man falls asleep
Man approaches
woman sexually
After cooking for
hours, they eat
Man discovers how much fun
they have even without sex
Man pretends
to be hungry
Man suggests
a bath together
Woman melts
After the bath the
man suggests opening a
bottle of Champagne
Man almost drinks the
whole bottle himself
Woman agrees
Man suggests a refreshing walk,
hoping that it will relax her
Man suggests
a short cut
Mans knee heals rapidly and he
suggests sex
Man suggests a trip to
Venice
Operations -- Prof. Juran
Woman gets excited and starts to
go through brochures
SEX
After a glass of wine the man
Finds courage to say what he’s
been trying to say all evening and
makes a confession of love
Gantt Chart
Vertical Axis: Always Activities or Jobs
Horizontal bars used to denote length of time
for each activity or job.
Activity 1
Activity 2
Activity 3
Activity 4
Activity 5
Activity 6
Time
Horizontal Axis: Always Time
Operations -- Prof. Juran
Summary
• Process Analysis Defined
• Key Terms and Metrics
• Process Flowcharting
• Gantt Chart
• Example: Milford Physicians
Operations -- Prof. Juran