Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: South Africa is ranked as one of the largest table grape exporting countries in the world.
The biggest markets for table grape exports have always been the EU and the UK, with
emerging markets in Eastern Europe and Asia. The growing demand for pre-packaged
fruit and vegetables in these markets are driven by factors like consumer comfort, hygiene
and quality. These consumer needs have given rise to stringent quality control standards,
putting more pressure on the producers to produce higher quality products.
This thesis investigates the use of check weighing as a tool to enhance the operational
effectiveness of table grape punnet packing. It looks at the current state of table grape
punnet packing in South Africa, then determines the operational effectiveness of current
packing practices and finally evaluates the merits of using automated check weighing as
an operational management tool to improve current systems.
Producers primarily make use of unskilled labour for the pre-packaging of table grapes,
making it difficult to consistently produce good quality products. Some packing systems
guide the operators towards filling punnets to the specified mass; some packing systems
also feature internal check weighing in some form. Although these features improve mass
accuracy and hence product quality, the packing processes are still prone to human and
machine errors. Producers employ internal quality controllers who try to identify and rectify
any human or machine errors as soon as possible.
The PPECB, a local statutory body, enforces the minimum quality standards for South
African exports by means of inspectors checking random product samples during
production. If products of sub-standard quality are found (including under mass), the whole
batch needs to be checked and repackaged where necessary, at great cost to the
producer. Pre-packaged products may be produced according to the minimum mass system or the
average mass system. The average mass system reduces the amount of raw product
giveaway and increases revenue, but it requires that all products are check weighed and
the masses recorded with a specified level of accuracy.
The addition of automated final product check weighing saw a significant reduction in the
occurrence of under as well as over mass punnets. It also managed to improve the
productivity of some packing systems. Subsequent experiments with the check weigher
using different setup parameters yielded much better measurement accuracy and would
reduce under and over mass punnets even more.
Considering the potential costs of having to repack batches due to the discovery of under
mass products, it would be viable to implement automated final product check weighing
even for small producers, with a payback period of less than 5 packing seasons depending
on the producer’s specific pack house layout.
The implementation of check weighing could not only reduce the risk of sub-quality
products being produced, but also open up entirely new market opportunities in a very
competitive market for products produced to the average mass system. / AFRIKAANSE OPSOMMING: Suid-Afrika is een van die grootste tafeldruiwe-uitvoerders ter wêreld. Die hoofmarkte vir
tafeldruiwe-uitvoere was nog altyd die Europese Unie en Verenigde Koninkryk, met
opkomende markte in Oos-Europa en Asië. Die groeiende behoefte vir voorafverpakte
vrugte en groente in hierdie markte word gedryf deur verbruikersfaktore soos
gemaksugtigheid, higiëne en kwaliteit. Hierdie behoeftes het tot gevolg gehad dat
strenger reëls en regulasies vir kwaliteitsbeheer ontstaan het. Dit plaas ekstra druk op
produsente om hoër gehalte produkte te produseer.
Hierdie tesis ondersoek die gebruik van weging van die finale produk as ʼn hulpmiddel om
die operasionele effektiwiteit van die verpakking van tafeldruiwe te verbeter. Daar word
gekyk na die huidige toestand van die verpakking van tafeldruiwe in Suid-Afrika. Die
operasionele effektiwiteit van bestaande verpakkingstelsels word bepaal. Die meriete van
ʼn “weging van die finale produk stelsel” as bestuurshulpmiddel is nagevors. Daar word
ook bespreek of die stelsel as bestuurshulpmiddel aangewend kan word om die
effektiwiteit van huidige verpakkingstelsels te verbeter.
Produsente maak primêr gebruik van ongeskoolde arbeid om tafeldruiwe te verpak. Dit
maak dit moeilik om konstante goeie kwaliteit te lewer. Sommige verpakkingstelsels
begelei die operateur om bakkies van ʼn spesifieke massa te produseer. Sommige
verpakkingstelsels bevat ʼn interne toetsweeg funksie van een of ander aard. Alhoewel die
funksies die akkuraatheid, produkmassa en dus produkkwaliteit verbeter, kan menslike- en
masjienfoute steeds ʼn impak hê op die verpakkingsprosesse. Produsente maak gebruik
van interne kwaliteitsbeheerstelsels wat poog om menslike- en masjienfoute so gou
moontlik op te spoor en te herstel. Die PPECB, ʼn staatsliggaam, dwing die minimum Suid-Afrikaanse uitvoerstandaarde af
deur middel van inspekteurs wat lukraak produkte tydens produksie ondersoek. Indien die
produkte nie aan die kwaliteitstandaarde (insluitend massa) voldoen nie, moet die hele
pallet nagegaan word en die bakkies moet reggemaak word waar nodig, teen ʼn groot
onkoste vir die produsent.
Voorafverpakte produkte kan volgens die minimum- of gemiddelde-massa sisteme
geproduseer word. Die gemiddelde-massa sisteem verminder die hoeveelheid druiwe wat
weggegee word en verhoog dus inkomste, maar dit vereis dat elke bakkie met ʼn bepaalde
akkuraatheid geweeg moet word. Daar moet ook rekord gehou word van die massas.
Die byvoeging van geoutomatiseerde finale produk toetsweging het ʼn aansienlike
verbetering in die hoeveelheid oor- en ondermassa bakkies tot gevolg gehad. Dit het ook
die produktiwiteit van party verpakkingsstelsels verbeter. Daaropvolgende weër
eksperimente met ander opstellingsparameters het baie beter akkuraatheid getoon en dus
kon die hoeveelheid oor- en ondermassa bakkies selfs verder beperk word.
Met inagneming van die kostes daaraan verbonde om ʼn pallet oor te pak as gevolg van
ondergewig bakkies, sou dit selfs vir klein produsente die moeite werd wees om finale
produk toetsweging te implementeer. Dit het ʼn terugbetalingsperiode van minder as vyf
pakseisoene, afhangend van die produsent se spesifieke pakstooruitleg.
Nie alleen kan die implementering van finale produk toetsweging die risiko van ondergewig
produkte verlaag nie, maar dit kan ook nuwe markgeleenthede oopmaak vir gemiddeldemassa
produkte in ʼn baie kompeterende mark.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/85683 |
| Date | 12 1900 |
| Creators | Smit, Rudi |
| Contributors | Treurnicht, N. F., Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xvii, 177 p. : ill. |
| Rights | Stellenbosch University |
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