Process AnalysisChapter 5

The Design ProcessThe Design Process

Managing TransformationsThe Production SystemInput Output

People Plants Parts Processes Planning and

Control

TransformationProcess

(Value Adding)

Transformation is enabled by The 5 Ps of OM:

[A.K.A. The 5 MsMan, Machines, Materials, Methods,And Management]

Process Flowcharting Defined Process flowcharting is the use of a diagram

to present (or represent) the major elements of a process (i.e. model).

The basic elements can include: tasks or operations (similar to a network diagram) flows of materials or customers, (or capital) decision points, and storage areas or queues

It is an ideal methodology by which to begin analyzing a process. (Think about.)

CommunicateOrder

Collectpayment

Enter Order PrepareProduct

15 seconds60 seconds

Correct Order

pointFail

point

Standard execution

time 30 seconds 15 seconds

20 seconds(e.g., raw, supplies)

Materials(e.g., raw, supplies)

Select and purchase supplies

Not seen by customerbut necessary to

performance

Line of visibility

Work Center Flow

Work Center Flow

Tasks or operations Examples: Giving an admission ticket to a customer, installing an engine in a car, etc.

Decision Points Examples: How much change should be given to a customer, which wrench should be used, etc.

Purpose and ExamplesFlowchart Symbols

Examples: Sheds, lines of people waiting for a service, etc.

Examples: Customers moving to a seat, mechanic getting a tool, etc.

Storage areas or queues

Flows of materials or customers

Purpose and ExamplesFlowchart Symbols

Example: Flowchart of Student Going to School

Yes

No

Goof off

Go to school today?

Walk to class

Drive to school

Types of Processes

Single-stage Process

Stage 1

Stage 1 Stage 2 Stage 3

Multi-stage Process

Types of Processes (Continued)

Stage 1 Stage 2

Buffer

Multi-stage Process with Buffer

A buffer refers to a storage area betweenstages where the output of a stage is placedprior to being used in a downstream stage

Other Process Terminology

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 and 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

Other Process Terminology (Continued) 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 case, the employee represents the limited capacity causing the bottleneck.

Pacing Refers to the fixed timing of the movement

of items through the process

Generic Labels for Types of Production Processes

Make-to-order (Single-piece/JIT or Pull)Only activated in response to an actual order.Both work-in-process and finished goods

inventory kept to a minimum.Make-to-stock (Batch/MRP or Push)

Process activated to meet expected or forecast demand.

Customer orders are served from target stocking level [i.e., Safety Stock].

Process Performance Metrics

Operation time = Setup time + Run time

Throughput time = Average time for a unit tomove through the system

Velocity = Throughput timeValue-added time

[time to produce each unit x batch size]

[time to prepare a machine or system to make a particular item or unit]

[for a particular machine or contiguous discrete system]

[time unit spends being worked on plus time spent waiting in queue]

[time unit spends being worked or the cumulative activity operation times]

[a.k.a. Throughput Ratio]

[> or = 1]

Cycle time = Average time betweencompletion of successive units

Takt time = Available production time .Rate of customer demand

[between starting and completing a job]

[manned shifts (w/wo set-up)]

[forecast or actual orders (with a lead-time)]

Process Performance Metrics (Continued)

German Concept

Process Performance Metrics (Continued)

Productivity = Output [total $ value, products, customers served] Input [total $ value, per resource, per labor hour]

Utilization = Time Activated [man or machine in operation]Time Available [manned shifts (w/wo set-up)]

Efficiency = Actual outputStandard Output

[measured in units]

[theoretical machine or system design, a.k.a capacity]

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.