An investigation into short production runs in spray drying plants of the New Zealand dairy industry : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Industrial Management and Engineering at Massey University

Copyright is owned by the Author of the thesis. Permission is given for

a copy to be downloaded by an individual for the purpose of research and

private study only. The thesis may not be reproduced elsewhere without

the permission of the Author.

AN INVESTIGATION INTO SHORT PRODUCTION RUNS IN SPRAY DRYING PLANTS

OF THE NEW ZEALAND DAIRY INDUSTRY

A t he s i s pre s ent e d in partial ful f i l m ent of the re quirement s f o r the d e gree of Doct or of Phi l o s ophy in Industrial

Man agem ent and Engin eering at Mas s e y University

ROBERT KAY

1982

,

THE ROA D NO T TAKEN

Two roads diverged in a yellow wood, And sorry I could not travel both

And be one traveler, long I stood

P�d looked down one as far as I could To where it bent in the undergrowth;

Then t ook the other, as just as fair, And having perhaps the better claim) Because it was grassy and wanted wear;

Though as for that the passing there Had worn them really about the same, And both that morning equally la3r

In leaves no step had trodden bla�k . Oh, I kept the first for another day!

Yet knowing how way leads on to way,

I doubted if I should ever come back . I shall be telling this with a sigh Somewhere ages and ages hence:

Two roads diverged in a wood, and I

I took the one less traveled by,

And that has made all the difference.

Robert Frost

ABS TRA C T

The features o f short production runs in spray­

drying plants o f the New Zealand Dairy Industry were examined and some methods developed to help improve productivity in dealing with them.

In particular a survey was carried out of the

managers o f all spray-drying plants in order to establish quantitative and qualitative in formation on short production runs. It was found that short production runs could be

classi fied into those caused by interruptions to runs, such as mechanical breakdown, those caused by specification

changes, and those caused by the decision to run the plant for a limited period, usually as a result o f the limited milk available for processing.

The e f fect o f capacity utilisation on spray-drying plants and the costs o f smoothed milk flow were examined and it was found that smoothed milk flow could not be

justi fied on economic grounds alone.

The occurrence o f short runs due to speci fication changes in other industries is documented as are methods to overcome their costs. It was concluded that the ma jor e f fects in spray-drying plants were likely to be through set-up cost and learning behaviour. However, it was

found that neither o f these seriously a f fected cost o f powder manufacture, short production. runs due to

speci fication changes were dealt with without excess costs over normal manu facture.

The relationship between run length and energy consumption and run length and processing rate were examined and quanti fied. A computer based management in formation system was developed to assist in the control o f costs in general and short production r�ns in particular

lD spray-drying plants.

li

ACKNOw.LEDGivl},NTS

There are many people who have been a great help in providing enthusiasm, inspiration and practical

assistance in carrying out this resear·ch . I am grate ful to the New Zealand Dairy Research Institute for kindly providing the funds to make it possible.

I would like to thank the staf f of the N . Z.D. R . I., 1

the N. Z . Dairy Board and IVJassey University, especially members of the Department o f Industrial l'-1anagement a..YJ.d

Engineering, who were always help ful and positive in tLeir advice .

Work in this industry has proven enjoyable and satis fying due to the generous co-operation o f managers o f spray-dr;-ying plants and other employees of dairy compe.nies. I"1y -chanks go to them.

In pa:;:-ticular I would like to thank Messrs P. Itead and A. Wolland o f Tui Co-operative Dairy Company, who have freely and willingly provided in fo�mation and help.

fVJy supervisors, Dr K.J. r:irkpatr·i�k, Dr W.B. Sanderson

cmd Professor J.K. Scott have been a continued source of constructive criticism and encouragement and I am most grate ful to them .

I would also like to eA�ress my thanks to my typist, Mrs I1. Garden, who has trans formed the manuscript into a readily intelligible form with skill and ei"ficiency.

Finally, I would like to thank my family, and especially my wi fe Jo, without whose support and

encouragement through the past three years, this work would not have been completed.

h.Kay

1. New Zealand Dai ry Rese arch Insti tute

ABSTRACT

ACKNOWLEDGMENTS TP.BLE OF CONTENTS

' .

iii

TABLE OF CONTENTS

LIST OF ABBREVI ATIONS

·GLOSSARY ·OF MILK POWDER SPEDIFICATIONS

CFJP TER ^ONE: INTRODUCTION

page

l

ii iii

lX X

1

LIST OF REFERENCES.

(

^{Chapter 1 ) 7}

CHAPTER ^TWO: THE SHORT PRODUCTION RLm IN HISTORY 8

. . . -

2 . 1 ^The commonali ty o f methods o f

manage ment o f production 8

2 . 2 The occurrence o f short production runs 1 0 2 . 3 Classi fication of manu facturing systems 11

2.4 Batch production 1 4

2. 5 Mass produc tion 1 9

2 . 6 Short runs in spray drying plants 2.'/

LIST OF REFERENCES,

(

^{Chapter 2 ) 30}

CHAPTER THREE: _{- .} THE OCCUR.ltENCE OF SHORT

. . . �

PRODUCTION RUNS IN SPRAY DRYING

PLA.t�TS 34

3.1 Preparation o f the survey 34 3 . 2 Results o f the written questionnaire 39 3 . 3 Results o f the interview questionnaire 51

LIST OF REFER

�

^CES_

(

^{Chapter_ 3 ) 68}

CHAPTER FOUR: ANALYSIS OF THE OCCURRENCE OF SHORT PRODUCTION RUNS

4.1 Introduction

4 . 2 Interruptions to production runs LJ-.3 Short production runs caused by

speci fication changes 4.4 Short daily running time 4�5 Additional in formation 4 . 6 Su mmary

LIST . . . OF REFERENCES

(

^{Chapter 4)}

69 69 69

72 76 77b 78 80

lV

page

·cF ^... APTER F IVE: THE E F FECT S O F SO ME ASPECT S

O F DAI RY I NDU ST RY I NF R ASTRU CTU RE 81 O N T HE S HO RT RU N P RO BLEM

5 . 1 Introduction 81

5.2 The determinants of New Zealand's

pattern of agricultural production 81 5 . 3 Comparison of costs of seasonal milk

production with smoothed production 83 5 . 4 Pressures causing a higher peak milk

supply 84

5-5 The market for milk powders 85 5 . 6 The New Zealand Dairy Board's effect

on short runs 5-7 Conclusion

LI ST OF REFEREN CE S ( Chapter-5 )

86 87 89

· C HAPTER S IX: T HE E F FECT S OF S HO R T PRO DU CT IO N RUNS I N- THE SP R AY DRYI NG PLANT 90

6 . 1 Introduction 90

6.2 Spra;y drying factory cost structures 92 6 . 3 Cost of start-up and shut-down in a

spray drying plant 96

6 . 4 Learning effects in spray drying pl�nts 99 6.5 Capacity utilisation in spray drying

plants 105

6 . 6 Cost effects of seasonal milk flow in

spray drying plants 109

6 . 7 Simulation of smoothing milk supply 116

6.8 Conclusion 120

LI ST OF REFEREN CE S ( Chapter 6) 121

CHAPTER SEVEN: CO NT ROL O F THE EF FED TS •OF S HO RT

'

P RO DU CT ION RU NS · I N SPRAY DRY I NG -PL.A..NT S

Introduction

Determination of the relationship.

between energy consllii!ption and daily run length

122 122

123

V

page 7-3 Factors affecting the rate of milk

processing in a spray drying plant 137 7 -4 Computer based management information

system 7-5 Conclusion

L IS':r OF REFERENCE S ( Chapter 7)

CHAP TER E IGH T: THE EFFEC T S OF TECHNOLOG ICAL

162 166 167

C HANGE ON SHOR T PRO DUC TION R UNS 168

8. 1 Introduction 168

8. 2 Mechanical vapour recompression 168

8. 3 Reverse Osmosis 169

8. 4 Energy developments 170

8.5 Computers �nd control 171

8.6 Evaporator cleaning 171

8.7 Ch anges in the size o f spray drying

plants 172

8.8 Conclusion 175

L I S T OF REFERN�CE S ( Chapter-S) 176

CFf__llx TE R N INE: CONCL U S ION 17 9

_APPEN DIX 1 : THE SPR AY DR YIN G-PL ANT 187 JlxPEL'J DIX 2: - QUE S T IONNAIRE LE:rTERS A.l\f D wRI T TEN

QUE STIONNA I RE BOOKLE T 189

APPEN DIX 3 : EXAMPLE OF " TEN DAIL Y" REPOR T 190 _APPEN DIX 4: EXAMP LE OF DAlL Y REPO R T 196 APPENDIX 5: B ACKGROUND TO ::L·EE EFFEC T S OF- SO ME

ASPEC T S OF DAIR Y IN DU S TRY INFR A- 200 S TR UC TU RE ON THE SHOR T R UN P ROBLEM

L IS T OF F IGURE S, GR APH S Jl� D TABLE S Figures

2.1 The manner o f action of .production management

2 . 2 Production systems

2 . 3 The production continuum

9 12 14

vi

page List of figures (cont )

6 . 1 Examples of computer print�uts

from simulation 118

188 A1. 1

Graphs 4 . 1

6 . 1 6 . 2

Diagram of spray drying process

Monthly average daily runn1ng time Theoretically expected result of learning behaviour

Number of failures per day vs day of run

7 7 100

103 6 . 3 Number of failures per day as percent

of all days of that number vs day 103 of run

6 . 4 Utilisation index versus cost per tonne 107 7 . 1 Example of scatter plot of daily total

oil consumption vs daily milk

volume (for spec 607) 125

7 . 2 �ate _of oil consum:ption per kilogram 129 of product vs production volume per day 7 -3 Rate of oil consumption per kg of

product vs raw milk volume 130 7 . 4 Rate_ of electricity consumption per

kg of product •.rs raw milk volume 7-5 Tukey plots of processing rate and

_131

processing time versus day number 13 9 7 . 6 Moving average plots of processing

rate and processing time vs day number 141 7-7 Cumulative sum plots of processing

rate and processing time vs day_number 142 7 . 8 Regression lines of processing rate

on _1/time 150

7 . 9 Predicted processing rate vs processing time

7 . 10 _Processing rate vs processing time,

151

days 69 to 92 156

vii

page Graphs

(

^{cont inued}

)

T ab l es

7 . 11 Process ing rat e vs pr�cessing t ime ,

days 106 t o 142 157

7.12 Process ing rat e vs process ing t ime , days 173 t o 210

7 . 13 Product ion rat e vs process ing time , days 69 t o 92

7.14 Product ion rat e vs proces_s ing t ime , days 106 t o 142

7.15 Product i on rat e vs proce_ss ing t ime , days _172 t o 210

2.1 I l lustrat ive est imat e of cost and scale ln car manufacture

3 . 1 Int ervi ew quest ions and information s ought

4 . 1 Occurrence of int errupti_ons t o product ion runs

4. 2 Fact ori es with short run l engths 6 . 1 1978-7 9 s e as on , average costs ln

do llars p er t onne and p ercent 6.2 Overall average p ercent age cost

structure

158 159 160 161

20 51

70 7 2 94

95 6 . 3 Spray drying fact ory inflat ion rat e 95 6.4 Result s of examinat ion of various

runs_ for 1earning b ehaviour 102 6.5 Summary of result s showing relat i onship

betwe en cost p er t onne _a.n.d capacity 106 6.6 Re sult s summary - Equal groups of

at equal p eriods 119

6.7 Result s summary - Two herds at vari ous

s eparat i ons 119

6.8 Result s summary - One t hird of herd calves lat er

7 . 1 Summary of resu lt s of r�gress ion

119

analys i s 127

7.2 Yield of product p er litre of raw m i lk 128

Vlll

T ab les

(

^{cont inued}

)

7.3 Values of co-eff ici ent of

det erminat ion

(R2)

for various regress i ons of process ing rate on process ing t ime

page

1 47

7.4 Summary of result s of r egression of 1 49 proces s ing rat e on 1 /process ing t ime

(hr)

A5.1 Estimat ed gro s s margins 1 981 -82 s eas on , J"'anawatu region

A5. 2 Exp enditure on average t own milk and

fact ory supp ly f arms for 1 978-79 season

A5.3 Percent age of New Zealand dairy product s by weight s o l d in Unit ed Kingdom

A5.4 The t en princip al milk powder market s for s e l ect ed years s ince 1 960

A5 . 5 Market sales of powders f or s e l ect ed

204

205

21 0 21 1

yea:r·s s ince 1 960 21 2

A5.6 Quant it i e s of dairy product s given access t o t he U . K . market during

the trans it ional period 21 3

B . M . P.

C . I . P.

Co -op E . E . C . hr

kg k. w.h . M.V .R . N . S . P. O . N.Z.C.D.C. N.Z.D.B. N.Z.D.R.I. R.O.

R.P.D.

· S.M.P.

Spe c U.K. W.M.P.

W . P . N . I .

N.C.

ix

LIST OF ABBREVI ATIONS

Buttermi l k p owder Clean in place Co -operat ive

European Economic Communit y hour

Kilogram

Kilowatt ho ur

Mechani cal vapour recompression Non-standard p urchase order Ne w Zealand Co -operative Dairy

Co mpany Lim ited Ne w Zealand Dairy Board Ne w Zeal �nd D airy Research

Inst it ute Revers e Osmos is

Rangitaiki Pl ain s Co -op erative Da iry Company Lim ited Skim m ilk p o wder

Spe c if icat ion United Kingdom Whole m ilk po wder

Whey prote in nitroge n index

Numerical control

X

GLOSS.A_-qy OF MILK POWDER SPEDIFICATIONS

Skim milk powder

Whole milk powder

Special (whole milk) products

600 I 633 ^l M301J 6021 607

J

662 672

800 801

}

802 803 821

}

823

J _L

^{900 930}

934 ^SMA

Medium heat Low heat High heat Heat stable

Basic, conventional Limited bulk density

range Vitaminised