Manufacturing Handbook of Best Practices 2011 Part 10 doc

10.1 DEFINITIONS process flow chart or process map so as to identify the specific location where defects or errors are created, where excessive cycle time is con-sumed, where cycle time

Trang 1

Jack B ReVelle, Ph.D.

10.1 DEFINITIONS

process flow chart or process map so as to identify the specific location where defects or errors are created, where excessive cycle time is con-sumed, where cycle time is most unpredictable, or where unacceptable costs are generated

operates without regard to whether it is efficient, effective, or competitive

• Event A nonmeasurable happening that occurs at a specific time, e.g., the start or finish of an activity

• Parallel Events Two or more events that take place simultaneously, i.e., concurrently

for process improvement are recorded when they are conceived for easy reference at a later time, e.g., a white board or easel paper

• Predecessor Event An event that must take place prior to the start of a specific event

• Process A series of sequentially oriented, repeatable events having both

a beginning and an end and which results in either a product (tangible)

or a service (intangible)

as process flow charts, process maps, and annotation The purposes of a process analysis are to expand the process stakeholders’ understanding of the entire process from suppliers to customers, including the critical linkages between the quality requirements and performance metrics of both inputs and outputs, and of the ways in which the voice of the customer drives the process

col-lection of process flow charts designed to facilitate understanding and enhancement of existing processes, both production and transactional

connected by arrows to graphically describe the sequential occurrence and interrelationships of events in a process

improving various phases or by redesigning all or most phases

SL3003Ch10Frame Page 227 Friday, November 9, 2001 1:52 PM

Trang 2

228 The Manufacturing Handbook of Best Practices

• Process Map A two-dimensional version of a process flow chart that also portrays handoffs and receipts of products or services from one person, organization, or location to another

• Series Events Two or more events that take place sequentially, i.e., one following or preceding another

be most efficient, effective, or competitive

• Successor Event An event that must take place following the finish of a specific event

• System A collection of processes, arranged in series or parallel, that has

a common beginning and a common end, and which together constitute

a program, a project, or an entire organization

10.2 PROCESS ANALYSIS

10.2.1 P ROCESS

What is a process? A process is a series of sequentially oriented, repeatable events having both a beginning and an end and which results in either a product or a service

A product, of course, is something tangible, something you can see, taste, or touch

A service is something intangible, something that you can’t see, taste, or touch, but which you know you’ve received For example, delivery of training is a service

10.2.2 S YSTEM

Well, if that is a process, then what is a system? A system is a collection of processes arranged in series or parallel, and which together constitute a program, a project, or

an entire organization A company, large, medium, or small, is an example of an entire organization An initiative might be a project such as the initial use of some new software A program could be an ongoing activity that is done periodically In any case, whether it is a program, a project, or an entire enterprise, it’s a collection

of processes

10.2.3 P ROCESS F LOW C HART

Having defined for baseline purposes what a process and a system are, now let’s review what we can do to better understand these processes, these basic elements

or components of an organization There are a number of different ways we can analyze a process The most common and one of the most useful forms is a graphic tool known as a process flow chart This chart is a series of geometric figures — rectangles, diamonds, and circles or various other shapes — arranged typically from left to right, and from top to bottom, connected by lines with arrowheads to show the flow of activity from the beginning to the end of the process

When a process is being created or an existing process is being analyzed, it is useful to create a process flow chart so that everyone involved, that is, all the stakeholders in the process, can see exactly what is supposed to happen from beginning to end without having to try to imagine it Each of us may have a picture

Trang 3

Process Analysis 229

in our own mind, a graphical portrayal of what the process flow looks like, but the reality may be different The only way we can be sure we understand that we have

a common perspective or outlook on the process is by graphing it as a process flow chart, a linear or one-dimensional process flow chart I say one dimensional to distinguish it from the two-dimensional graphic that we are going to talk about shortly, known as a process map

Let’s talk about the creation of the process flow chart Traditionally, people have created process flow charts from the first step to the last I don’t, and the reason is that, when people put this flow chart together, they are looking at processes in the same way they look at them every day, so there is a high potential for missing something What I suggest people do as we bring them together in a room to create

a process flow chart is to start with the end in mind, a concept understood by everyone familiar with Stephen Covey’s The 7 Habits of Highly Effective People.

We begin by defining the last step or the output of the process and then start asking the question sequentially, “What has to happen just before that?” If we know

we have a specific output or step, we ask what must be the predecessor event or events that must take place to satisfy all the needs so that the step we are looking

at can take place So we work backward from the last step to the first step and keep going until someone says, “That’s where this whole thing begins.” Now we have defined, from the end to the beginning, the process, graphed as a process flow chart Some people might question why you want to do it that way The analogy I use that is very effective is this: suppose I were to ask you to recite the alphabet You would say A, B, C, D, E, F, G … without thinking, because you have done it hundreds, perhaps thousands, of times

But if I were to ask you to recite the alphabet backward, you would probably say Z and have to stop and think what happens before that, what letter precedes Z What most people do, I have discovered, is first to do it forward to find out what the letter is and then come back and say that the letter before Z is this, and the letter before that is this, and so on Working the alphabet backward makes people look at

it in a way they have never looked at it before, noticing the interrelationships between the predecessor and the successor events

The same psychology of working backward applies in dealing with our pro-cesses, whether we are dealing with a process of building a home, working with accounts payable, developing a flow chart, understanding a process as it relates to training, or whatever the case may be Establishing the process flow chart from the last step to the first step is a very strong and powerful way to help people understand what their processes really look like

10.2.4 P ROCESS M AP

Once the process flow chart has been created and everyone is satisfied that it truly reflects the order in which the events take place with regard to predecessor and successor events, the next step is to create a process map Earlier I said a process map is created in two dimensions We are going to use exactly the same steps we used in the process flow chart, except now, instead of just having the flow go from left to right, we take the people, positions, departments, trades, or the functions that

Trang 4

are involved in the process and list them vertically down the left-hand side from top to bottom

For example, it might be department A, B, or C; person X, Y, or Z; or trades such as concrete, plumbing, or framing Then, we take the rectangles that we created

in our process flow chart and associate them with the various functional areas, departments, persons, or trades listed on the left-hand side What you see is a series

of rectangles being built from left to right and also moving up and down the vertical axis we have created on the left-hand side of our process map In so doing, we see what might look very much like a sawtooth effect with blocks going up, down, and across Thus we end up with a view of the handoffs from one person to another, one function to another, or one trade to another, so we can see where queues are being built and where the potential for excess work in process is being created among the various areas of responsibility (listed down the left-hand side)

This gives us a very clear, visual picture of some of the things we might want

to consider doing in terms of reordering the various steps to minimize the total number of handoffs that are a part of this process, recognizing that every time there

is a handoff, there is a strong potential for an error, an oversight, something left out,

a buildup of a queue, the creation of a bottleneck, or the like

In creating our process map we gain tremendous insights into what we can do to continuously improve our processes Remember, the order of the steps may have been absolutely vital at one time, but with changes in technology, people, and responsibilities, what we did then may no longer be valid, and we need to periodically assess or review our processes The use of a process map is an excellent way to do that

Now, in addition to looking at the process flow chart and process map in terms

of the sequence and the handoffs, we can also use the process flow chart and the process map to assess cycle time and value-added vs nonvalue-added events or steps

in the process The technique I use is to ask everyone in the room to assess the cycle time of the process that was just evaluated using a process map or process flow chart Does it take 3 hours, 5 days, 10 weeks — whatever? When we get an agreement

of 6 to 8 hours or 6 to 8 weeks — whatever the final range may be — we go through and evaluate each individual step, asking how long each step takes When we have gone all the way through that, we arrive at the grand total of all the individual step estimates and compare that to the estimate that the group has already made of the overall process

What we frequently find is that the sum of the individual steps is only 20 to 30% of the overall total That quickly presents an image of a lot of lost and wasted time, costly time that could be used for other, important purposes If, for example,

a process is estimated to take 6 weeks, but the sum of the individual components takes a week and a half, it’s obvious that we have some time we can save the company Now, what needs to be done? Where are the barriers, the bottlenecks in the process that we can study, where can our trades (for example) share responsi-bility? Instead of having a particular trade come back three, four, or more times to

do some little job that takes a half hour, an hour, another trade already on-site could

be doing it for them That is a very effective way of reducing cycle time Steps can

be eliminated and days upon days can be banked for use in more important projects

Trang 5

10.3 PROCESS IMPROVEMENT

10.3.1 “A S I S ” VS “S HOULD B E ”

Now let’s look at the “as-is” vs the “should-be” conditions When we create the first process flow chart or process map of an existing process, we refer to that as the as-is process, i.e., the status of a process as it is currently operating It gives us

a baseline to create the new, revised process that we call the should-be process Working together, the process improvement team is now able to view the as-is process in juxtaposition with the should-be process that they have created Subsequent to the creation of the should-be process map, the team begins to build a bridge from the as-is to the should-be process The bridge is supported by

a series of steps that we must go through to change the process from the as-is way

to the way it should be

A good example of that is the creation of some superhighways where conven-tional surface roads exist During the building effort, traffic still has to flow, so as

we move from the as-is surface streets to the should-be superhighway, we have to

go through a series of steps, closing down and opening various components of the roads to support as much as possible the flow of traffic that never stops Picture the Los Angeles freeway traffic any time of the day or night This approach graphically illustrates what we need to do to move from the as-is process map to the should-be process map These are things we might have otherwise overlooked

10.3.2 A NNOTATION

Using either a process flow chart or a process map, a process improvement team can easily identify specific locations within a process where events should be mon-itored to determine the extent of defects, errors, oversights, omissions, etc Moni-toring is usually accomplished using statistical control charts, e.g., X-bar and R, C,

P, Np, U, and other charts Chapter 15 on statistical process control (SPC) presents information on this topic

Annotation is the development of a listing of defects and variances associated with the process being analyzed Each known defect or variance is assigned a number

by the team Then the team annotates (assigns) each defect or variance to one or more events on the process flow chart or map At this point the team evaluates the combined impact of the defects or variances at each event Based on this evaluation, the team determines where SPC control charts should be physically located on the manufacturing floor, design center, or office In addition, the team identifies which defects or variances should be counted (attribute/discrete data) or measured (con-tinuous/variable data)

The combined effect referred to above is determined by the quantity of defect

or variance identification numbers annotated at each event Those events with the greatest incidence of identification numbers have a greater need for monitoring using SPC control charts than the events with few or no identification numbers This is a simple application of the Pareto principle, also known as the 80-20 rule In this case, 80% of the SPC control charts will be needed to monitor 20% of the process events

Trang 6

The annotation methodology is also valuable in identifying where, within an as-is process, changes are needed in the creation of a should-be process

10.4 PROCESS ANALYSIS AND IMPROVEMENT NETWORK (PAIN) 10.4.1 R EASONS FOR PAIN

There are several reasons for using the Process Analysis and Improvement Network (PAIN) Whenever a process exhibits undesirable attributes, it is incumbent upon the process owner, process stakeholders, members of a process improvement team (PIT), or any other interested parties to take timely and appropriate corrective actions

to eliminate or at least to reduce the presence or influence of the negative attributes The most common of these negative attributes are

• Process too long (excessive cycle time)

• Process too inconsistent (excessive variation)

• Process too costly (excessive cost per cycle)

10.4.2 PAIN — M AIN M ODEL ( F IGURE 10.1 )

• Senior management identifies a process critical to success of the organi-zation

process stakeholders, and process subject-matter experts (SMEs)

improvement

process flow chart

• Start the development of the as-is process flow chart with identification

of the final step in the process and then a backward pass through the process, finishing with its first step

two forward passes

• With the assistance of its facilitator, the team should now convert the as-is process flow chart into its corresponding should-be process map

• At this point, the process improvement team has a variety of options from which to select, depending upon its objectives As noted above, there are

a number of reasons for PAIN The following models and discussions are offered to clarify the team’s choices

three steps remaining to complete the PAIN These steps are spelled out

in the final blocks of the PAIN — main model (Figure 10.1)

Trang 7

10.4.3 PAIN — M ODELS A T HROUGH G

PAIN — Model A (Figure 10.2) The objective of this sequence of events is to reduce process cycle time The process improvement tools, cause-and-effect analysis (also known as the fishbone diagram or the Ishikawa diagram), and force field analysis are explained in numerous books on continuous improvement

PAIN — Model B (Figure 10.3) The objective of this sequence of events is to reduce process variation The process improvement tools, cause-and-effect analysis (also known as the fishbone diagram or the Ishikawa diagram), and force field analysis are explained in numerous books on continuous improvement

PAIN — Model C (Figure 10.4) The objective of this sequence of events is to reduce the number of process steps This is accomplished primarily by identifying the value-added (VA) and non-value-added (NVA) steps that exist within the as-is process

PAIN — Model D (Figure 10.5) The objective of this sequence of events is to reduce the cost per cycle of using a process After determining whether the costs in question are direct or indirect and the pertinent cost categories, the objective is accomplished through the sequential use of several process improvement tools The improvement tools, Pareto analysis, cause-and-effect analysis (also known as the fishbone diagram or the Ishikawa diagram), and force field analysis are explained

in numerous books on continuous improvement

PAIN — Models E and F (Figures 10.6 and 10.7) The objective of these models

is to provide guidance in the reduction of transactional errors and defects (Model E,

ID Critical

Process

Establish Process A&I Team

Convene Team with Facilitator

Facilitator Provides A&I Tutorial

Team Starts

Process Flow

Chart with

Backward Pass

Team Completes

"As Is" Process Flow Chart with 2

or More Forward Passes

Team Converts Process Flow Chart Into Process Map

Team Creates

"Should Be"

Process Map

Team Leader Facilitates Transition to

"Should Be"

Process

Repeat, as needed, Biannually Team Determines Its

Objectives

B C D A

E

F

G

Reduce Process Cycle Time

Improve Process Documentation

Reduce Production Defects

Reduce Transactional Errors

Reduce Cost per Cycle

Reduce Number

of Steps

Reduce Process Variation SL3003Ch10Frame Page 233 Friday, November 9, 2001 1:52 PM

Trang 8

A

Measure/Estimate Individual Step Durations

Calculate Overall Duration

Apply 80/20 Rule to ID the Few Steps that Consume the Most Cycle Time

Use Cause & Effect

Analysis to ID Cause(s)

of Excessive Time

Consumption

ID 2 or More Potential Corrective Actions

Use Force Field Analysis

to Select the Most Appropriate Corrective Action

Collect Cycle Time Data

to Confirm Cycle Time Reduction

Implement Corrective

Actions

B

Measure/Estimate Individual Step Durations(Most Optimistic Pessimistic)

Collect Data When Estimates Vary

Apply the 80/20 Rule to ID the Few Steps Containing the Most Variation

Use Cause & Effect

Analysis to ID

Cause(s) of

Excessive Variation

Use Force Field Analysis to Select the Most Appropriate Corrective Action

Implement Corrective Actions

Collect Individual

Step Durations to

Confirm Variation

Reduction

Trang 9

Figure 10.6) as well as production errors and defects (Model F, Figure 10.7) The model

is based on the Deming-Shewhart Plan-Do-Check-Act cycle The earliest version of the model was created in 1985 as a part of a continuous improvement seminar When the model is first introduced to a process improvement team, it is important to gain consensus from the team members regarding the rationale of event selection and arrangement

FIGURE 10.5 Objective: reduce cost per cycle.

C

Determine Desired % Reduction in No of Steps

Count Actual No of Steps

Calculate No of Steps to be Reduced

Count No of

Hand-Offs from One

Function to Another

ID Non-Value-Added (NVA) Steps

Redraw Process with

VA Steps above Time Line & NVA Steps Below

Calculate VA/NVA Ratio (Bigger is Better)

Set Improvement

Goal for VA/NVA

Ratio

ID NVA Steps that can be Totally Eliminated

ID NVA Steps that can

be Combined with Other NVA Steps or with VA Steps

Select NVA Steps for Elimination or Combination

Perform Necessary

Changes to Eliminate

/Combine NVA Steps

OR

Type of Cost

?

Identify Cost Categories

Direct

Cost

Indirect

Cost

Collect Relevant Recent Cost Data

Failure Costs (Internal & External) Appraisal Costs

Prevention Costs

Conduct Pareto Analysis of Cost Data

Use Cause and Effect Analysis to

ID Cause(s) of Greatest Cost

Use Force Field Analysis to Select Most Appropriate Corrective Action

Implement Corrective Action

Collect Additional Cost Data to Confirm Cost Reduction

Controllable Expenses

Clean-Up Expenses

Miscellaneous Expenses D

Trang 10

FIGURE 10.6 Objective: reduce transactional errors/defects.

E

Identify Internal

(Operational) &

External (Customer)

Transactional Problems

Prioritize Problems

Select & Define Primary Problem

Identify Process(es) Associated with Primary Problem

Describe Process(es)

Identify Specific Steps which Require Analysis

Collect

Attribute or

Variable

Data

Determine Defects to

be Counted & Charted (Performance Metrics)

Determine Critical Dimensions to be Measured and Charted (Performance Metrics)

Design Data Collection (Tally) Sheet

Decide How Collected Data Should be Bundled

& Graphed

Initiate Data Collection

Analyze Data For Process Competitiveness (Quality,Cost,Sch.)

Process

Competitive

?

Institute CI

Determine Root Cause(s)

Develop Consensus for Continuous Improvement Strategy

Determine &

Implement Corrective Action Sequence

Evaluate Results

of Corrective Action

Institute Process

Redesign

Process

Redesign Risk Factors Manageable?

Develop Process Redesign Flow

Modify Process

Commit to CI

Monitor Process

to Assess On-Going Status

Select & Define Next Primary Transactional Problem

Establish Performance Improvement Objectives

Identify Scopes

& Target s

Assess Internal

& External Process Factors

Select New Technologies &

Methodologies

Develop New Process

Test New Process ?

Evaluate &

Communicate New Process

No Go

Yes No

No Yes

Go

Định dạng
Số trang	17
Dung lượng	480,98 KB