A holistic approach to injection moulding optimisation for product quality and cost through the characterisation of reprocessed polymeric materials and process monitoring. Experimental evaluations and statistical analysis of multiple reprocessing of unfilled and short glass fibre filled polypropylene materials. An optimised methodology to realise minimum product cost at an acceptable product quality.
AuthorElsheikhi, Salah A.
Campean, I. Felician
Product quality and optimisation.
The University of Bradford theses are licenced under a Creative Commons Licence.
InstitutionUniversity of Bradford
DepartmentSchool of Engineering, Design and Technology
MetadataShow full item record
AbstractThe plastics industry is one of the fastest growing major industries in the world. There is an increase in the amount of plastic used for all types of products due to its light weight and ability to reprocess. For this reason, the reprocessing of thermoplastics and the usability of reprocessed materials are gaining significance, and it is important to produce and consume plastic materials in an environmentally friendly way. In addition, rising raw material cost linked to the increased oil prices encouraged for reusing of the plastic materials. The aim of this research was to study and optimize the injection moulding process parameters to achieve a trade-off between the product cost and product quality, measured through mechanical properties and geometry, based on using regrind ratios. The work was underpinned by a comprehensive study of multiple reprocessing effects in order to evaluate the effect of process parameters, material behaviour, reprocessing effects and possible links between the processing parameters and key properties. Experimental investigations were carried out, in particular, focused on the melt preparation phase to identify key process parameters and settings. Multiple reprocessing stages were carried out; using two types of PP material: unfilled and short glass filled. A series of tests were used to examine product quality (mass, colour and shrinkage) and physical properties (density, crystallinity, thermal stability, fibre length, molecular weight, in-line and off-line viscosity, tensile strength, modulus of elasticity, elongation (%) and flexural strength). This investigation showed that the mouldability of the filled and unfilled PP materials, through the successive reprocessing stages (using 100 % regrind), was observed to be relatively consistent. Given the link between the processing parameters and key product and material properties, it is possible to manufacture products with minimal loss to part quality and mechanical properties. The final phase of the work focused on process optimisation study for short glass fibre filled PP material and the identified key process parameters (melt temperature, screw rotational speed, holding pressure, holding time and injection rate). A response surface experiment was planned and carried out for three reprocessing stages (0 %, 25 % and 50 % regrind). The fitted response surface models were utilised to carry out the trade-off analysis between the operating cost (material cost, energy cost and labour cost) and product quality (dimensions and tensile strength) Based on the optimal moulding conditions, the operating cost was reduced (from stage I as a reference), by 24% and 30 % for stage II and stage III respectively. A small, perhaps undetectable, change in product dimensions was noted. In addition, a small reduction in tensile strength was noted (from stage I as a reference), by 0.4% and 0.1 % for stage II and stage III respectively. The same data was applied in other countries (Australia, USA, Brazil, Libya and China) to manufacture the same product; and it was observed that the cost was reduced with increasing of regrind ratio. But the significant reduction of the cost, essentially, depended on those countries which have low wage rates (e.g. Brazil, Libya and China). For example, the cost of moulded product manufactured in China is £ 0.025 (using 50% of regrind), while the cost of the same product produced in Australia is £ 0.12, hence giving a total saving of 79 % and making it a valuable issue to be considered in industry.
Showing items related by title, author, creator and subject.
Optimal design and operation of multivessel batch distillation with fixed product demand. Modelling, simulation and optimisation of design and operation parameters in multivessel batch distillation under fixed product demand scenario and strict product specifications using simple dynamic model in gPROMS.Mujtaba, Iqbal M.; Mahmud, Mohamed Taher Mustafa (University of BradfordSchool of Engineering, Design and Technology, 2010-09-28)Increased interest in unconventional batch distillation column configurations offers new opportunities for increasing the flexibility and energy efficiency of batch distillation. One configuration of particular interest is multivessel batch distillation column, which can be viewed as a generalization of all previously studied batch column configuration. In this work, for the first time the optimal design and operation tasks are developed for multivessel batch distillation with strict product specifications under fixed product demand. Also, in this work, two different operation schemes defined as STN (State Task Network) in terms of the option and numbers of off-cuts were considered for binary and ternary separation. Both the vapour load and number of stages in each column section together with the production sequence are optimised to achieve maximum profit function. The performance of the multivessel batch distillation column is evaluated against the performance of conventional batch column with a simple dynamic model using binary and ternary mixtures. It has been found that profitability improves with the multivessel system in both separations. gPROMS, a user-friendly, software is used for the modeling, simulation, and optimisation.
Investigating the relationship between quality management and productivity: An analysis of quality and productivity in Pakistani manufacturing companies.Barber, Kevin D.; Breen, Liz; Iqbal, Tahir (University of BradfordSchool of Management, 2013-12-05)The aim of this study is to determine the extent to which Quality Management Practices has been effectively adopted and implemented by Pakistani manufacturing companies and to identify best practices for adoption by the companies. The study employed primary and secondary data sources to determine the relationship between QM and Productivity. The study used quantitative methodology for data collection and analysis. The survey responses were categorised into foreign owned companies (FOC¿s) and local owned companies (LOC¿s). The outcome of the descriptive and statistical analysis of the survey responses and secondary data of the companies found that, although most of the companies were aware of the significance of the QM practices and Productivity, FOC¿s were found to have performed highly better in the adoption and implementation of QM practices in their companies compared to locally owned companies. The study also revealed that there is positive relationship between quality and productivity of the manufacturing companies. The evidence deduced from the study shows that foreign owned companies have performed better compared to local owned companies in terms of quality and productivity. Furthermore, the evidence from this study also points out that, automobile sector of Pakistan performed well in the adoption and implementation of QM practices. Strong positive link between quality and productivity was found in the case of automobile companies. This study therefore recommends for manufacturing companies in Pakistan to effectively adopt and implement Quality management practices that encapsulate the study¿s framework for adoption of QM practices (see figure 7.1).
Prostaglandin D2 production in FM55 melanoma cells is regulated by ¿-melanocyte stimulating hormone and is not related to melanin production.Masoodi, Mojgan; Nicolaou, Anna; Gledhill, Karl; Rhodes, L.E.; Tobin, Desmond J.; Thody, Anthony J. (2010)This study shows that prostaglandins in human FM55 melanoma cells and epidermal melanocytes are produced by COX-1. Prostaglandin production in FM55 melanoma cells was unrelated to that of melanin suggesting that the two processes can occur independently. ¿-Melanocyte stimulating hormone (¿-MSH), which had no effect on melanin production in FM55 cells, stimulated PGD2 production in these cells without affecting PGE2. While cAMP pathways may be involved in regulating PGD2 production, our results suggest that ¿-MSH acts independently of cAMP, possibly by regulating the activity of lipocalin-type PGD synthase. This ¿-MSH-mediated effect may be associated with its role as an immune modulator.