Check weighing in table grape punnet packing:Opportunities in the development of operational effectiveness

[摘要] 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, withemerging markets in Eastern Europe and Asia. The growing demand for pre-packagedfruit and vegetables in these markets are driven by factors like consumer comfort, hygieneand 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 operationaleffectiveness of table grape punnet packing. It looks at the current state of table grapepunnet packing in South Africa, then determines the operational effectiveness of currentpacking practices and finally evaluates the merits of using automated check weighing asan 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 systemsguide the operators towards filling punnets to the specified mass; some packing systemsalso feature internal check weighing in some form. Although these features improve massaccuracy and hence product quality, the packing processes are still prone to human andmachine errors. Producers employ internal quality controllers who try to identify and rectifyany human or machine errors as soon as possible.The PPECB, a local statutory body, enforces the minimum quality standards for SouthAfrican exports by means of inspectors checking random product samples duringproduction. If products of sub-standard quality are found (including under mass), the wholebatch needs to be checked and repackaged where necessary, at great cost to theproducer.Pre-packaged products may be produced according to the minimum mass system or theaverage mass system. The average mass system reduces the amount of raw productgiveaway and increases revenue, but it requires that all products are check weighed andthe masses recorded with a specified level of accuracy.The addition of automated final product check weighing saw a significant reduction in theoccurrence of under as well as over mass punnets. It also managed to improve theproductivity of some packing systems. Subsequent experiments with the check weigherusing different setup parameters yielded much better measurement accuracy and wouldreduce under and over mass punnets even more.Considering the potential costs of having to repack batches due to the discovery of undermass products, it would be viable to implement automated final product check weighingeven for small producers, with a payback period of less than 5 packing seasons dependingon the producer's specific pack house layout.The implementation of check weighing could not only reduce the risk of sub-qualityproducts being produced, but also open up entirely new market opportunities in a verycompetitive market for products produced to the average mass system.

[发布机构] Stellenbosch University