10paper mt kurup ashok leyland manufacturing quality ... · pdf fileashok leyland ltd. 2...

1 Guidelines for improving manufacturing quality through Process Reliability Rank Up

Manufacturing Quality Improvement through PRRU

M Thulaseedhara Kurup (Ashok Leyland Limited) Email: [email protected]

Priyank Bhatt (Ashok Leyland Limited) Email: [email protected]

Foreword

A barber is working in his shop. A slight deviation in the quality of his work will create an altercation

between him and his customer. A customer buys a cloth from a shop and after a month he founds that the

color of the cloth has faded. Quality of the product or process may sometimes be visible instantly while

sometimes after a period of time. But in both the cases the ultimate loss is customer dissatisfaction.

Different kinds of problem with quality may be seen in different sectors. Quality may relate to service, raw

material used and process etc. When we come to manufacturing, the term quality comes into picture at

the very beginning, i.e. process.

Two years ago, when I joined PNR plant in quality department, I started working with Q = I 2 A strategy

and, within two years by the virtue of strengthen inspection and immense effort of all the executives

towards quality improvement which significantly reduced the DPV level.

Once DPV was brought down the need was to develop a scientific methodology for assurance. With a

team, we developed a methodology “Process reliability rank up”.

‘Process reliability rank up’ is the first step towards quality assurance. It follows the same PDCA cycle of

TQM. This study is written for the need of micro level of the process requirement.

From the inception of the idea team member Priyank and other have assiduously done brain storming for

giving it the shape so that it can be a common sense of everyone. I guided them throughout this project in

every aspect to map our processes with global standards.

This book is going to be the backbone of quality department. I wish the team to excel and keep improving

the quality with different innovations.

Thulaseedhara Kurup Head – Total Quality Management Ashok Leyland Ltd.


TABLE OF CONTENTS

Foreword ...................................................................................................................................................... 1

Preface ......................................................................................................................................................... 3

Abbreviations ............................................................................................................................................... 4

Introduction .................................................................................................................................................. 5

Purpose: ................................................................................................................................................... 7

What is Process Reliability rank up? ....................................................................................................... 7

Effect of a Process Reliability Rank Up (PRRU) ................................................................................ 7

Concept behind the selection of manufacturing quality assurance items ...................................... 8

How to use a Process Reliability Rank Up: ............................................................................................ 9

Step 1: Process Mapping ..................................................................................................................... 10

Step 2: Defect modes capturing ......................................................................................................... 11

Step 3: Defects v/s Process Mapping ................................................................................................ 11

Step 4: Occurrence Prevention & Flow-out prevention – Current Controls ................................. 12

Concept behind occurrence prevention and outflow prevention ................................................ 13

Step 5: Current Assurance Rank Evaluation .................................................................................... 14

Each Process standards rank table: Assembly Processes ........................................................ 14

General Assessment Ranking (Concept behind assurance rank evaluation) ......................... 17

Precaution for using a standard ranks table: ................................................................................ 17

Judgment method when there are plural preventive processes ................................................ 18

Step 6: Setting Target assurance rank .............................................................................................. 20

Step 7: Kaizen Planning ....................................................................................................................... 21

Step 8: Kaizen Implementation ........................................................................................................... 22

1. Physical improvement that reduces human decisions ......................................................... 23

2. Double-checking human decisions ......................................................................................... 23

3. Improving the performance level of operators ....................................................................... 23

Drawbacks and advantages of human operations ....................................................................... 23

Step 9. Post-Kaizen Rank Evaluation & Gap Analysis ........................................................................... 24

Step 10. Continual Improvement ............................................................................................................. 24

Implementation journey: ............................................................................................................................. 25

Overall Effects: ........................................................................................................................................ 25


Preface

“Process Reliability Rank up” is a fundamental of Quality Assurance. For delivering world class product every organization has to assure its own manufacturing process. The basic principle of “Process Reliability Rank-Up” is the same to strengthen the process. That means to enhance the reliability of the process.

Reliability refers to the frequency of defect occurrence by the process. Frequent defect occurrence is possible if the process is less capable. It will also reflect an uneven waviness in process stability.

To uplift such processes and deliver a world class quality product, policy must be clear. For the same Q = I2A (Quality = Inspection X Improvement X Assurance) is being practiced in Ashok-Leyland PNR. Initially to visualize & standardize the situation inspection activities had been initiated. After identifying the problem improvements activities (JDI, KKD & QC Story) started for achieving more stability in the process.

After these two activities; then only process can go for the final step i.e. assurance that mean to make process more capable. And which will guarantee for the world class quality which is 0.2 DPV.

For this assurance purpose “Process Reliability Rank Up” is a methodology. Fundamental of PRRU is to make process more reliable and more flexible w.r.t. human intervention. So that process can guarantee the assurance level of a product even if the process is human dominating.

“Process Reliability Rank-up” is a step towards Quality Assurance for achieving world class quality.

This book will guide for the import0061nce of WHAT? WHY? & HOW? part of the problems. That will tell what needs to improve in the process? Why it needs to improve? And ‘How’ part will tell that How it can be improve? This will lead to the implementation of KAIZEN. This book will also guide about ‘What’ KAIZEN should implement & How to promote KAIZEN plans.

For initiating this methodology same has been implemented on Chassis & Trim line for Boss truck.

We hope that, the book will be a helpful for all the users to make their job easy and simple & will make them understand for practical implementation of “Process Reliability Rank-up” (PRRU) to realize its advantages.


Abbreviations

1. PRRU Process reliability rank up 2. PFD Process flow diagram 3. SCC Self-certification card 4. QA Quality assurance 5. JDI Just do it 6. QG Quality Gates 7. PFMEA Process failure mode effect analysis 8. 3G Genba, Genbutsu, Genjitsu


Introduction

In the era of competition every industry wants to work harder & smarter, so that they can sustain their

position in the market to gain more & more profit.

Meanwhile, every individual also wants to grow in a healthy & happy environment. But in the reality work

is not that much SIMPLE & EASY.

By virtue of “not simple” & “not easy” work, everyone jumbles the work. That always carries a tray of worries

for all. Because of this, industries fall short in terms of Quality, Cost, Delivery and Profits.

In the same manner people lose their motivation for working in an industry. Instead of mental peace,

stability & growth they always seek for new industrial opportunities. That causes instability in industrial

progress & also fails to gain the trust of its employees. There are following cases which represent the

actual picture of few industries (not necessarily in Ashok Leyland.)

1. Worries of an Associate:

Mr A is working in an assembly line. As line have varieties of models to be produced every day.

He always faces a problem in finding the correct part no. for assembly as there is no SOP. There are

so many parts which look almost similar and there is no other way to distinguish such parts rather than

their part number. That arises so many chances when Mr A fails to remember right part no. and picks

a wrong part from the bin. When this problem identified in the line he does troubleshooting for the

correct part, which makes his task ‘not easy’. And that also causes frequent breakdown of the line.

Is this the only one case in the line?

Is this the first & last case in the industry?

Is this a special case of Mr A?

2. Worries of a supervisor

Mr B is a supervisor for the assembly line. In his area there is a process where oil filling process takes

place. This process is done without any oil dispenser unit. A man who owns that process is responsible

for all decisions like quantity of oil & filling procedure etc. Because of running line & obstruction from

the people working around, there are frequent times when some oil drops on the floor. Because of

sophisticated engine assembly process in the same stage, somewhere oil filling in a cabin tilt pump

cannot captured in a regular practice. When oil filling process repeats many times the floor gets oily

& slippery. That slippery area always becomes a problem for the supervisor Mr B because anyone

can easily slip down and that can cause a safety issue. Mr B always runs for housekeeping department

to ensure proper cleaning. This makes Mr B’s work ‘much harder

What should be the job of a supervisor?

Is Mr B a very abnormal supervisor?


3. Worries of a QA Person

Mr C has a responsibility for quality inspection before handover product to next internal customer.

There are few check points like to identify the proper gap b/w two surface, to check the free play( in

mm) or to identify the right location for the brand stickers. All these decisions are purely based on his

own judgment without any gauges or equipment. Same thing get repeated by his immediate customer

at incoming quality inspection person. Now both the person takes the decision based on their own

intelligence. And now we found many chances where both of them had clash over the quality of

product. It may be possible that defect may flow out from the second inspectors too. Also Mr C found

it’s ‘too difficult’ to stand on a common sense (platform) with the next inspector to satisfy his immediate

customer.

Is Mr C is only one who faces such problem?

Is Mr C is not capable enough for capturing defects? If NO then who?

Is ‘Double checking’ is really fruitful for such cases?

4. Worries of the management

Welded cabin of a vehicle before coming to trim line passes through the paint shop. There are few

defects that has actually occurred in weld shop and yet not captured before painting. When these

defects realised in trim line they contribute to paint shop defects. While paint shop report claims that

such defects cannot generate because of their process. That enhances the troubleshooting activities

of management only without any result. That makes management job more hectic & unpleasant.

Is this the only management team who do such troubleshooting?

What should be the real worries of a management?

In all the above cases one thing is common for all the concerns, either the defects (problem) has not been

captured where actually it had occurred or there is no standard methods to filter out defects at right place.

For most of the cases this is because process is not fail-proof or existing process does not know

whether it is capable of meeting product’s new specifications or that process has to be modified according

to the new requirements.

It can be said that process reliability rank is low. Here process reliability rank consists of both the

existing standards for defect occurrence prevention & defect flow out prevention.

These all concerns or in other way lower reliability of the process indicate for cost of poor quality.

Because if defect is getting generated; that must be rectified before hand over the product to its end

customer and all the rework & rectification cost contributes to cost of poor quality.


Purpose:

The purpose of this method is “To detect the defect at the source of its occurrence to

reduce cost of poor quality”

What is Process Reliability rank up?

Process reliability rank up tool is a matrix showing the relationship between the manufacturing assurance

items (or defect items) of the product that should be assured in the phase of manufacturing of the product,

and intended to evaluate the occurrence and outflow prevention assurance ranks in the processes in

relation to these manufacturing assurance items (or defects items). The objective of Process reliability

rank up is to identify the drawbacks of processes (Process with low assurance rank) to prevent the transfer

of such defects to the subsequent processes, including customers, and thereby to enhance management

and improve processes. Figure 1 shows a general format of Process Reliability Rank Up.

Effect of a Process Reliability Rank Up (PRRU)

i. A matrix makes clear defect modes (the state that assurance items are not met) in the phase

of manufacturing processes in which these defect modes occur, and the assurance rank of the

processes that prevent the outflow of the defect modes. In consequence of this, the outflow of

defects can be prevented.

ii. The quality assurance rank of the process (line) can be objectively evaluated based on an

assurance rank table and, at the same time, items that should be improved are made clear.

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iii. The participation of production-related sections (Manufacturing dept.) in the preparation of a

PRRU network helps them understand the role of the process against quality and select

management and equipment maintenance points, and raises the operator’s awareness for

quality.

iv. Item, which are likely to be missed because they were dependent on process designer’s know-

how or operator’s experience can be reduced as a matrix makes them easier to identify, and

members can discuss them more easily.

v. Since each manufacturing assurance item can be reviewed through all processes, duplicate

inspections (Outflow prevention) can be found, and inspections can also be reduced and

optimized.

Concept behind the selection of manufacturing quality assurance items

Consulting the defects mode of process FMEA, drawings (quality control point setting requests), design

FMEA, and past defect, discuss among related departments which manufacturing assurance item to

select, and select all manufacturing assurance items that adversely affect products.

In addition to it, make clear and enter on the Process Reliability Rank up (PRRU) network sheet how the

manufacturing assurance items affect products and whether these items are specified for critical control

based on the effects of defects of process FMEA and drawings.

Reconsidering past defects from the PRRU network standpoint reveals some assurance items that were

not completely reviewed.

It is important to select each assurance item.


How to use a Process Reliability Rank Up:

To use ‘Process Reliability Rank up’ method a network sheet should be used. Network sheet is basically

for making a matrix and mapping of assurance items with respect to the defects.

Following steps must be followed while executing Process Reliability Rank Up:

Step 1. Process Mapping

Step 2. Defect modes capturing

Step 3. Defects v/s Process Mapping

Step 4. Occurrence Prevention & Flow-out prevention – Current Controls

Step 5. Current Assurance Rank Evaluation

Step 6. Setting Target Assurance Rank

Step 7. Kaizen Planning

Step 8. Kaizen Implementation

Step 9. Post-Kaizen Rank Evaluation & Gap Analysis

Step 10.Continual Improvement.


Step 1: Process Mapping

Process Reliability Rank Up tool is to strengthen the health of a manufacturing process. So first of

all it is very important to have knowledge of ‘What is actual practice (process)?’, ‘Why is this sequence?’,

& ‘How the product is getting made? All the value added process should be noted and counter checked

with available control i.e. PFD and SCC.

Abnormalities related to process adherence can be visualized easily by this and it can be fixed before

moving to next step. Such abnormalities must be documented for future reference; it may be done by JDI*

concept. Now the current process should be filled inside the PRRU network sheet horizontally.

Here it is important to define the place of Quality Gates (QG). It can vary as per the defect capturing QG.

Ideally QG should be mentioned as per the actual line layout however if it is not possible to show in one

sheet then all the Quality Gates should be mentioned on the right side of the network sheet just after the

processes. This includes quality gates; PDI; Sendai whatever is applicable for the particular process.

Example of process mapping is being shown in table 1.2

* JDI is a technique to solve the problem immediately if solution is known.

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Step 2: Defect modes capturing

After process mapping it is important to capture all the defects that have been generated in the process.

All defects must be captured from every aspect whether they are external or internal complaints.

For defect capturing QG, PDI data can be taken. And it should also include field failure data.

While capturing the defects it is important to take into consideration the severity of that defect.

3G (Actual Place, Thing & Situation) must be practice for defect mode capturing. For each defect,

frequency of the defect should be noted. Frequency can be for a particular period. Whatever period it is;

that must be true representative of all the defects occurring in that manufacturing process. For frequency

(occurrence) calculation; data can be taken from P-chart or any daily defect monitoring sheets. Frequency

will be filled in past defects column in the Process Reliability Rank-Up network sheet.

Apart from frequency, one must also consider the special characteristics (Critical, Safety & Important) of

product/process. Special characteristics of the part/product are available in the drawing. Also special

characteristics of the process are available in the Control Plan. Also special characteristics of process are

available in the form of Q+ & Qs.

Step 3: Defects v/s Process Mapping

After defect capturing it is easy to relate the defect with respective process. According to this defects are

listed in Production assurance item/Defect mode column row wise with respect to the process where the

defect is generating. Along with process related defects & part related defects are also captured. The

symbol circle and ‘<>’ diamond can be used for denoting the point where defect is getting generated

& where it is getting detected, for e.g.

It is convenient to list down the defects in the sheet, like whichever defect is generating first with respect

to the process that should come first. It helps in the better visualization of work.

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Step 4: Occurrence Prevention & Flow-out prevention – Current Controls

After step 3, it will be clear where the defect is getting generated. How and why defect is getting

generated? For knowing this capability of process to prevent defect from occurrence & flow-out must be

judged.

For each defect, study the process controls given in PFD, PFMEA, Control Plan, WIS etc., and take out

the existing available controls for occurrence prevention and flow out prevention for that particular defect.

For supplier/part related defects, same documents at the Supplier end must be studied. Also, for design

related issues, DFMEAs must be referred.

The contents of these controls should be entered in the Process Reliability Rank-up sheet against the

defect in the “Current quality assurance level” column under the subgroup “Occurrence Prevention” &

“Flow-out prevention”.

The occurrence and flow out prevention levels of process reliability rank up items must be correctly

evaluated and at the same time, there must not be any difference in evaluation between operators in

charge of the process. It is recommended that each department machining/assembly prepares a process

standard rank table for each group of products based on the organizational guidelines.

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* 100% inspection & rectification at Quality gate* Fitment verification during subsequent operation.* Verification after vehicle offtrack.* Verification in VTS / Vehicle painting

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Contents Contents

* Instructions and training provided by Line executive * Instructions & training given to Stores associates to supply parts free from dust , rust or paint damages

* Checking by operator doing fitment* Checking by Inspector at QC gate

* Instructions and training provided by Line executive * Instructions & training given to Stores associates to supply parts free from dust , rust or paint damages

* Checking by operator doing fitment* Checking by Inspector at QC gate* Paint Touch up at Paint Booth prior to despatch

Current quality Assurance Level

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Reference controlOccurrence Prevention Flow-Out Prevention

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Concept behind occurrence prevention and outflow prevention

Process reliability rank-up is an approach to evaluate assurance ranks in connection with both occurrence

and flow out prevention. However, there is a possibility of incorrectly evaluating the difference between

occurrence prevention and flow out prevention.

In a word, the difference between occurrence prevention and out flow prevention is as follows:

Occurrence prevention : Assurance until the machining/assembly of products is completed

Out flow prevention: Assurance of machined/assembled products


Step 5: Current Assurance Rank Evaluation

Each process is evaluated based on its capability for defect occurrence & flow-out prevention. The

contents of Occurrence & Flow-out prevention taken out from Control plan & other documents are judged

on the basis of an “Each Process Standard Ranks Table” as follows and accordingly level as 1,2,3,4 is

decided.

Each Process standards rank table: Assembly Processes

O : Occurrence prevention

Given below are evaluation criteria for occurrence prevention. Evaluate according to the defect mode in

consideration like incorrect parts, missing parts etc.

: Flow out prevention

The rank of outflow prevention is based on 100% checks, but if processes can be theoretically

judged by lot assurance, such as batch processing, they may be judged by lot assurance. However,

rank 1 cannot be evaluated by lot assurance.

However, each item is judged acceptable if at least one of the requirements with at least one

condition

1 2 3 4 - Occurrence prevention automatically carried out by machine

- Occurrence prevention in place but partially needs human intervention.

- Occurrence prevention relies on human operation greatly but with limited amount of KAN-KOTSU required.

- Difficult to follow standard

- Not enough process capability

- Occurrence prevention relies heavily on KAN-KOTSU.

- Impossible to assemble incorrect parts Alarm activated: - Collation done with manuals - No manuals - Machine does not operate when detecting incorrect parts.

- When an incorrect part is detected (lamp, buzzer).

(actual parts, photos and part no.) - It is left to the associate's sense.

- Impossible to take incorrect parts. - When an incorrect part is taken (lamp, buzzer).

Alarm activated: - Assured with operation manual sheet - No operation manual sheet.

- When part are missing (lamp, buzzer).

(including Process professional).

- When necessary parts are not taken (lamp, buzzer). - Qty. check implemented.

- All processes where foreign materials can get into are covered.

- A device to prevent foreign materials adhesion is prepared (Air blower, Vacuum etc.)

- Assured with operation manual sheet - No operation manual sheet.

(Rubber cap, covers etc.) (including Process professional). - It is left to the associate's sense.

Wrong assembly - Machine design to prevent wrong assembly.

- Alarm activated when parts are set incorrectly (Lamp, Buzzer).

- Assured with operation manual sheet (including Process professional) (With e.g. of assembling position and orientation)

- No operation manual sheet.

- Skipped processes not possible - Alarm activated with skipped processes (Lamp, Buzzer)

- Assured with operation manual sheet - No operation manual sheet.

M hi d t t h d t ti

Basic concept - Machine detects abnormality 100 % by

itself.

- 4M for normal operation is standardised and occurrence

prevention is sufficient.

- Occurrence prevention made on machine not sufficiently enough, but there is enough process

capability.

Skipped process

Foreign materials

Ass

embl

y

Incorrect parts

Missing parts - Machine does not operate when detecting missing parts.

Level

Table 5.1


O: Occurrence prevention: Assurance until the machining of products is completed

* Occurrence prevention must be evaluated according to each subcategorized item (within solid lines)

and fulfil all items within the solid lines.

* However, each item is judged acceptable if at least one of the requirements with "*" is met.

* When a characteristic for preventing an assurance item is comprehensively evaluated (A, B, C, D) as an

assurance item for a subassembly or part.

: Outflow prevention: Assurance of machined parts

Level <1> <2> <3> <4>

Basic concept - Flow-out prevention automatically carried out by machine.

Flow-out prevention in place but partially needs human intervention.

- Flow-out prevention relies on human operation greatly.

- Standard not sufficiently specified/followed.

Items - Machine detects abnormalities 100% by itself.

Some standards and procedure not sufficiently specified/followed.

- High potential of defect out-flow from machine.

- Not sufficient flow-out prevention on machine.

- 100% Defect detection within the process. Automatic rejection implemented.

- 100% defect detection within the process and alarms when detecting defects (Lamp, Buzzer etc.)

- Assured with operation manual sheet (including KOUTEI-PRO)

- Abnormality cannot be cleared unless detect part is rejected.

- 100% check within the process with measuring instruments/gauges

- Double check implemented 100% sensory within the process (1 item checked by two different associates)

- Double check implemented 100% within the process and at inspection with measuring instrument/gauges.

- Double check implemented 100% sensory within the process and at inspection.

- Enough process capacity and sample check done.

- Impossible to operate. - Enough process capability.Data recorded on control chart, recording paper etc. to control the change points( with plot or figure)

Performance inspection (bench) - 100 % defect detection at inspection and a tomatic rejection after machine stop

- 100 % defect detection at inspection and alarms hen detecting defects (lamp b er)

- Assured with operation manual sheet (incl ding KOUTEI PRO)

- No operation manual sheet

Assembly - No operation manual

sheet.

① ② ③ ④Basic concept Equipment alone can

prevent defects and is also capable of detecing them.

Quality still has to be assured (partially) by members.4M is standardized and most defects are prevented in the ordinary work condition.

Relying on human labor greatly, however does not have to rely on the element of intution or method of individual.It is not sufficient for prevention of occurrence with equipment; however process capability exists.

* Difficult to adhere to the standards.* Process capability not sufficient from equip aspect.* Team members rely on knuck.

Physical action Equipment detects any improper condition and incomplete assembly and does not transfer parts to the next process.

Equipment detects and warns any improper condition and incomplete assembly.

Human action There is no operation involving human decisions.

An operation partly involving human decisions

A standardized human operation

Not standardized

Heat treatment

Hardness, Structu* The treatment conditions (temperature, current, voltage, time, gas, concentration) are constantly monitored, and the interlock is

* The treatment conditions (temperature, current, voltage, time, gas, concentration) are constantly monitored, and a warning is issued.

* The treatment conditions (temperature, current, voltage, time, gas, concentration) are checked at the start of operation.

* Treatment conditions are not monitored.* There is no standard operation.

Surface treatmen

t

Film Thickness Blister

* The treatment conditions (temperature, current,

* The treatment conditions (temperature, current, voltage, time, gas,

* The treatment conditions (temperature, current, voltage, time, gas,

* Treatment conditions are not monitored.* There is no standard

Basic

Items

Treatm

ent p

rocess

Table 5.2


* The assurance of outflow prevention is based on 100% checks, but if processes can be theoretically

judged by lot assurance, such as batch processing, they may be judged by lot assurance.

However, rank 1 cannot be evaluated by lot assurance

* However, each item is judged acceptable if at least one of the requirements with "*" is met.

Basic concept Defect prevention is equipment wise. Also, capable of knowing equipment breakdown.

Assurance is partially provided by members. During normal operation. 4M is standardized and escape prevention is sufficiently done.

Largely relying on members. Standardization and adherence of standard is questionable. Equipment wise escape prevention is not perfect.

* Lack of standards, or not adhered as they are supposed to.* It is likely to have defects esape, equipment wise.

Physical action Any defects can not be transferred to the next process

Any defects can be detected and a warning is issued.

Human action There is no operation involving human decisions.

An opeartor partly involving human decisions

A standardized human operation

Not standardized.

100% assurance * Equipment detects problems and interlocked

* Equipment detects problems and issues a warning.* Measuring instruments or gauges are used to check all parts and determine whether

* Visual or sensory check * Defects are difficult to detect.* There is no operation standardized.

LevelBasic

Items

Treatment Machinin

1 2 3 4

Table 5.4


General Assessment Ranking (Concept behind assurance rank evaluation)

Based on the combination of occurrence ( , , , ) & flow out prevention level (<1>, <2>, <3>, <4>),

general assessment rank in terms of A, B, C, D, E, F has been allotted according to table 5.1

Precaution for using a standard ranks table:

When using a standard ranks table, focus on the following points to avoid misjudgment is essential.

If it is difficult to judge, decision can be taken by referring to “basic concept” at the top of the standard

ranks table.

1. Evaluate occurrence prevention by solid lined frame. To determine the occurrence prevention of

each machining process, all machining conditions must be covered and correctly evaluated. It is,

therefore necessary to evaluate occurrence prevention in relation to each item (in solid-lined

frame) subdivided in the standard table and fulfill all items within the solid-lined frames.

2. However, each item within lined judged acceptable if at least one of the requirements is met.

3. The evaluation of outflow prevention by lot assurance is limited. Incorrect parts, missing parts,

wrong assembly and product characteristics are assurance items for all products in principle. If

lot assurance is theoretically possible, for example, a machining process is batch processing,

outflow prevention may be judged in the “Lot assurance” field. A lot is a shift or daily basis.

However another frequency is acceptable if the definition of lots is established by theory and

defects can be prevented within the plant.

4. Judge the rank of any machining method is not included in the standard ranks table based on

“Basic concept”

Occurrence

Flow out

<1> A A A B

<2> A B C D

<3> A C D E

<4> B D E F

Table 5.5


Judgment method when there are plural preventive processes

If there are plural preventive processes while evaluating assurance ranks with a PRRU network, they are

handled as described.

1. Outflow prevention:

If there are plural outflow prevention processes (there are plural outflow prevention ranks), apply the

highest outflow prevention rank among those after the originating process (the process with an

occurrence prevention rank).

In figure 5.1 for example judgment of gap throughout check <4> and final inspection <3> are

given, its evaluation is considered the higher rank <3> because the same gap (length) is checked

by different methods and the higher rank represents it.

2. Occurrence prevention If there are plural originating processes (there are plural occurrence prevention ranks), evaluating

the assurance rank in each occurrence process, and apply the lowest occurrence prevention rank.

However note that there are exceptions.

i. Independent type: Lowest rank

This is the basic type of occurrence prevention. If the characteristics of occurrence

prevention do not correlate with one another and are independent, apply the lowest rank.

For example, “occurrence prevention rank of grinding process 3 ” and ‘occurrence

prevention rank of press fitting process 2 are given to the assurance item ‘foreign

substance’ in figure 5.2. ‘Foreign substance’ is independent in the two processes, and its

evaluation is considered the lower rank 3

Rear

axle

tigh

teni

ng

Final

Insp

ectio

n

Leve

l

Leve

l

3

43 3 3 D C

Contents Contents

HELPER SPRING & HELPER BKT GAP LESS

* Instructions and training provided by Line executive to operator as per WIS* Instructions & training given to Stores associates to supply parts free from dust , rust or paint



Targ

et ra

nk

Occurrence Prevention Flow-Out Prevention

Gene

ral a

sses

smen

t

Production assurance

item

Cutti

ng

Grin

ding

Insp

ectio

n

Acce

ptan

ce in

spec

tion

Pres

s fitt

ing

Final

Insp

ectio

n

Leve

l

Leve

l

3 2 3 3 3 D C

Preceding Process Main Process

Contents Contents

Foreign substance

* Instructions and training provided by Line executive to operator as per WIS* Instructions & training given to Stores associates to supply parts free from dust , rust or paint damages



Targ

et ra

nk


Gene

ral a

sses

smen

t


item

Figure 5.6

Figure 5.7


ii. Correlative type: Higher rank This is an exception to occurrence prevention. If the characteristics of occurrence

prevention correlate with one another, apply the highest rank. For example, different

methods are used for occurrence prevention in connection with the assurance item “pull-

out strength” in figure 5.3, there is a correlation between “dimensional assurance of parts

2 and load monitoring 1, in this case, its evaluation is considered the higher rank 1 as in

the case of outflow prevention.

iii. Low effect type: Not included in judgment There are also exceptions to occurrence prevention of the independent type. If there is characteristics

whose effect on the assurance item is low, it may be excluded from judgment of the item. For

example: when “U-bolt tightening” is an assurance item. Tightening torque is the important factor for

occurrence prevention characteristics. Occurrence is being insured by DC nut runner 2 in main

process however the effect of tightening at Sub-assembly 3 is lesser then DC nut runner torqueing

3 .Here in this case, enter 2 in the evaluation field of the PRUU network sheet for classification.

Shaf

t

Body

Term

inal

Thin

Line Ac

cept

ance

insp

ectio

n

Pres

s fitt

ing

Fusi

ng

Fina

l Ins

pect

ion

Leve

l

Leve

l

2 2 1 3 1 3 A A

Part Main Process

Contents Contents

Pull out strength: 10 N




Targ

et ra

nk


Gene

ral a

sses

smen

t


item

Load

ing

Plac

ing

Tigh

teni

ng

Acce

ptan

ce in

spec

tion

Prel

oadi

ng

Tigh

teni

ng

Torq

uing

(DC

nut R

unne

r)

Fina

l Ins

pect

ion

Leve

l

Leve

l

3 2 3 2 3 C A

Sub Assembly Main Process

Contents Contents

U-bolt tightening less




Targ

et ra

nk

Occurrence Prevention Flow-Out PreventionGe

nera

l ass

essm

ent


item

Load Monitoring

Dimensional assurance parts

Figure 5.8

Figure 5.9


Step 6: Setting Target assurance rank

According to our Quality policy, we are committed to provide world class products and services to delight

customers while complying with all regulatory requirements. Therefore, to achieve World Class Quality

Product, target rank for each defect mode is given based on world class quality criteria which are as

follows:

Rank Characteristics

A Safety related defects B Functional related defects C Defect which can be sensed

1. Safety related defects In this category we consider those defects which can cause an accident resulting in injury, death or vehicle fire. Also, items required to meet legal regulations are also taken in this category. Such items need to be intensively controlled in the manufacturing process so that defect, related to these items does not occur at all or even if it occurs, it is not allowed to flow out. This ensures that not even a single product safety problem occurs in the field. Accordingly, the target rank for these defects is set at A.

2. Functional related defects Those defects which can prevent the driving function from working on the vehicle or have a potential to seriously interfere with the running function of the product are taken in this category. Such defects can cause huge customer dissatisfaction and must be strictly controlled in the manufacturing process. This ensures that no large volume of failure/damage occurs in the field and reliability target of the product is maintained. Accordingly, the target rank for these defects is set at B.

3. Defect which can be sensed: Defect modes like vibration, noise, poor aesthetics etc. which leads to customer irritation come in this category. The target rank for such defect items is set at C.


Step 7: Kaizen Planning

For kaizen planning, gap analysis is the initiating step. For each defect item, we should analyze the gap between current assurance level and target assurance level. Accordingly, kaizen plan is formulated. For the purpose of Kaizen planning, we need to analyze 3G for each defect mode, that is:

1. Genba: Actual work place at which defect occurs 2. Genbutsu: Actual thing (product) 3. Genjitsu: Actual situation (real facts and data)

During kaizen planning step, multiple ideas need to be generated for each defect item in order to bring them to target quality assurance rank through various approaches possible. One of the methods for idea generation is brainstorming. Ideas generated should be evaluated for their expected rank as shown below. An example of kaizen planning is given below.

Figure 7.1


Step 8: Kaizen Implementation

How to promote improvements?

There is no human operation that does not cause any human error, & the incidence of human errors depends on the difficulty of each operation or the level of each operator’s performance level. Reducing operations involving human decisions & increasing decisions by equipment is the basic concept of assurance level improvement through a Process reliability rank-up to improve process assurance levels. However, because of manual processes, there is a limit to equipment-related improvement as well. The key to assurance level improvement is “How to create ideas & promote activities to reduce human errors.” Below figure shows the steps of improvement.

Giving “Physical improvement” in step (1) the first priority, promote improvement so that the target rank will be achieved. If the target cannot be achieved in physical improvement, improve process assurance levels by “Double Checking” in step (2) or “Improvement of performance level of operators” in step (3). Manage the improvement activities of step (2) & (3) with an assurance level below-target control chart to monitor human operation levels & approve the release of products.

Step (1); Physical improvement that reduces human decisionsExamples:

Preventing reverse assembly using fail-proofingAutomatic judgment by sensors

Step(2):Double checking human decisions-Application conditions (All must be met)

Visual & sensory checks to prevent outflow of defectsProcedures involving motions such as point & checksDifferent operatorsDifferent workshops

Step (3): Improving the performance level of operatorsDesignating human operation as qualified operations & there by improving operation levels.Daily check of human operation levels by supervisors, etc.


1. Physical improvement that reduces human decisions

To reduce operations involving human decisions, implement physical improvement by means of “Fail-proofing” and “Jig & Tool” as the first priority. Monitoring Fail-proofing and human errors through equipment is effective in preventing human errors. For the prevention of outflow of defects, on the other hand, the way products are checked with measuring instruments, sensors, and the other devices is a key factor.

2. Double-checking human decisions

In this step, review the assurance items which are rated as outflow prevention rank 3 and failed to achieve the target rank in physical improvement in step (1). This step is intended to improve processes assurance ranks by performing a visual check & sensory check twice (double checks) for the purpose of prevention of outflow of defects.

However merely superficial double checks may not ensure improvement effects and it is, therefore, necessary to fulfill all application conditions.

3. Improving the performance level of operators

In connection with the assurance items which failed to achieve the target rank in step (1) and to which step (2) was not applicable, make attempts to "improve the performance level of operators" involved in human operations.

An improvement plan must be formulated and systematically carried out in such a way that target ranks can be achieved.

Drawbacks and advantages of human operations

It is necessary for us to understand the drawbacks & advantages of human operations to promote

process assurance level improvement activities through a Process reliability rank-up in manual

processes.

1. Human errors (drawbacks)

There is no human operation that does not cause any human error. Human errors are not what

operators want to make.

These errors will be a serious problem if they endanger operator’s (customer's) lives. For manual

processes, measures to prevent human errors are important, and dealing with such problems

through a Process Reliability rank-up is indispensable.

2. Variation in assurance levels depending on operators' condition (drawback)

Whether a defect, which occurs with one out of several thousand products, can be detected without fail in

appearance checks, for example, is a concern, and it must be considered separately from machines. The

skillfulness of operators must also be considered.

For the above mentioned reasons, it is important to "provide operators guidance & education," "compile


easy-to-understand operation manuals," and "prepare boundary samples." Additionally, "ensuring proper

breaks,” "creating a comfortable working environment," and activities to raise the awareness of operators,

such as "loyalty to the company," are required.

3. Making processes at low labor cost (advantage)

Labor costs in Southeast Asia are about one-tenth of those in Japan. The reliability of human processes

can, therefore, be improved by:

Making it rule to perform operator-assigned inspection twice and thereby prevent the outflow of

defects with a higher level of reliability

Defining human operations as operation procedures including checking operations thereby prevent

human errors.

If we cannot spend money on equipment, we must assign costs to maintain quality in a

comprehensive manner,

4. Detecting unexpected problems (advantage)

There are things that machinery cannot do but operators can deal with. Operators can never perform

routine, repeated operations better than machinery. On the other hand, there are unexpected problems

that machinery cannot detect but operators can find out.

However, process design entirely relying on operators’ expertise, or old-fashioned "artisanship'"

Step 9. Post-Kaizen Rank Evaluation & Gap Analysis It is important to evaluate the post KAIZEN rank on the certain frequency. It tells about the effectiveness,

cost and implementation effort. User are advised to develop multiple KAIZEN and evaluate under these 3

categories. Most suitable and feasible KAIZEN idea must be selected which must be in line with the

business objectives.

Step 10. Continual Improvement Improvement is continual journey. PRRU recommends that to make processes more reliable and for

achieving acceptable target ranks i.e. A,B & C strategy should be in 3 steps. First of all should target to

eliminate E & F that means make all processes standard and after that 1 more step improvement and in

final step should target to acceptable ranks.However, it is most appreciable if based on business objectives

KAIZEN can be implemented directly to achieve acceptable target rank.


Implementation journey:

Journey of PRRU has started with Ashok Leyland, PNR plant which is the youngest plant among AL plants.

AL PNR established initial quality controls through quality gates, standardization and improvement

methodology supported to achieve quality objectives. The plant has benchmarked all quality parameters

within 3 years of journey.

PRRU was the unique & most important concept at AL PNR plant which could make the process

improvements so much speedy.

At AL PNR, total 1474 defects were mapped with existing processes and the level of process reliability

were ranked. Only 192 processes were ranked as good. By FY17, total good ranked process increased

from 192 to 327 and total defect recurrence reduced from 1474 types to 471 types.

PRRU also proved itself ‘a guide’ for Kaizen Quantity and Quality. Crossing 5000 improvements (small /

big) in a month is very normal at ALP. These KAIZEN bank has helped other plants to improve their

processes significantly and efficiently.

Overall Effects:

AL PNR reduced its DPV drastically by implementing Quality Gates but PRRU helped plant to

sustain and further reduce DPV up to 0.13 (better than the CV Industry benchmark).

After successful pilot at AL PNR, this methodology has been deployed to 5 more plants of AL.


12

34

AA

AB

AB

C (

*)D

A

C (*)

DE

BD

EF

Crea

tion

date

: dd

.mm

.yyy

y

12

34

56

78

910

1112

1314

1516

1718

1920

2122

23

Level

Level

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Targ

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PRRU

Net

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Revi

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date

Revi

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cont

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(ent

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Refe

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Control Plan

Work Instruction Sheet

PFMEA

PFD,Drawings,SCC & Others

Curr

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General assessment

PE(P

RJ. L

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(MGR

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No.Critical control designation

Past defect (yr/mth)

Functional - characteristic

KAIZEN Date

Completion Date

Added Part number

Proc

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Occu

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Cont

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Cons

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Repr

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Annexure 1.1


Occu

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even

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Flow

-out

Pre

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Leve

lLe

vel

Line

Nam

e :

Pers

on in

Cha

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ntro

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Crea

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date

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n da

te :

Com

plet

ion

Dat

e

Post

-KA

IZEN

Ra

nk

KAIZ

EN P

lann

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Shee

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ty A

ssur

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Pos

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Cont

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Cont

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KAIZ

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lan

Curre

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rank

Targ

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rank

Unac

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No.

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Resp

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Dept

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chd

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Act

l.

PR (M

GR)

PF (P

RJ I)

Annexure 1.2

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