Este é um trabalho teórico-empírico que visa principalmente verificar o estado da literatura científica no que diz respeito à consideração dos custos de financiamento da necessidade de capital de giro (NCG) aplicado em mercadorias (NCGp), especialmente em relação aos aprimoramentos do modelo do lote econômico de compras/produção (LEC/LEP). A revisão de literatura mostra diversos modelos aprimorados do LEC/LEP que usam as técnicas de valor presente líquido e fluxos de caixa descontados para considerar o custo do capital no tempo, mas, segundo diversos autores, a diferença entre o LEC original e o uso de tais técnicas é desprezível. Além do mais, o uso destas técnicas não significa que tais modelos tenham incorporado o custo do financiamento da NCGp. Alguns trabalhos, mais recentes, já trazem simulações que levam em consideração o NCGp, outros até já exibem a fórmula NCGp = Estoquesp+Clientesp+Fornecedoresp. Neste trabalho foram feitas 128.000 simulações estocásticas de um modelo dinâmico, de onde se extraíram as variáveis da DRE de cada membro de uma cadeia de suprimentos (CS) hipotética. Foi testada a hipótese de ser este modelo aprimorado, porque incorpora o custo do capital de giro empregado nas mercadorias, mais correto que o modelo que não o incorpora. Para fazer este teste, foi feita uma modelagem (em Excel R) de uma CS contendo dois fornecedores industriais, uma fábrica, um atacadista e um varejista. O modelo recebe como inputs as demandas agregadas do varejista nos dias de cada simulação, que são 360 dias. Os dados foram importados no software estatístico R e as variáveis de saída foram então analisadas nos diversos cenários, regimes e tipos de demanda. Os resultados da análise dos diferentes cenários mostram que é importante considerar os custos financeiros da NCGp. / This is a theoretical and empirical work that primarily aims to check the status of scientific literature with regard to the consideration of the costs of financing the working capital needs (WCN ) applied to goods (WCNp), especially in relation to improvements of economic order/- production quantity (EOQ/EPQ) models. The literature review shows several EOQ/EPQ enhanced models that use net present value and discounted cash flows techniques to consider the cost of capital over time; but according to several authors, the difference between the original EOQ model and with the use of such techniques is negligible. Moreover, the use of these techniques does not mean that such models have incorporated the cost of financing the WCNp. Some latest papers make simulations that consider the WCNp, others have even used the formula WCNp = Inventoriesp +Receivablesp +Payablesp. In this study we made 128,000 stochastic simulations of a dynamic model, from where the were obtained the result\'s variables for each member of a hypothetical supply chain(SC).We tested the hypothesis that this enhanced model, because it incorporates the cost of working capital employed in goods, is more correct than the model that does not. For this test, we made a model (in Excel R) of a CS containing two industrial suppliers, a factory, a wholesaler and a retailer. The model takes as inputs the aggregated demands of the retailer in the days of each simulation, which is 360 days. Data were imported into R statistical software and the output variables were then analyzed in different scenarios, regimes and types of demand. The results of the analysis of different scenarios showed that it is important to consider the financial costs of WCNp, maybe incorporating them into an enhanced EOQ/EPQ model.

Study question: How can the process for article classification and procurement be improved in a new implementable inventory policy with the objective to reduce inventory costs. Purpose: The purpose of this degree project is to design a procurement policy which helps to minimize the annual capital tied up in inventory. Method: The procurement policy is created by a mixed method with a focus on the quantity inputs of secondary data and minor involvements of qualitative from primary data. Inventory management formulas from the theoretical framework constitute the conducted model. With the ground work from theory and inputs from interviews, the research approach has been deductive and followed the guidelines of Ali and Birley (1999). ABB Capacitors is the case study of this degree project which the model has been tested and verified upon. Conclusion: The degree project resulted in procurement policy which includes a calculation model and inventory analysis which has shown success from the theoretical comparisons, and it indicates that the procurement policy is functioning as intended. Mathematical formulas are mere tools in a procurement policy, experience and know-how are two pieces which importance should not be neglected.Weaknesses of this policy concern inventory capacity because the calculations’ purpose is to minimize inventory cost by procuring to an economic optimum. There is a chance that physical structure allows fewer quantities than what is financially best. The policy is recommended for manufacturing industries. / Frågeställning: Hur ska artiklar till lagret köpas in och klassificeras i en ny inköpsstrategi med målet att minska lagerkostnaderna och minimera lagernivåerna till givna förutsättningar. Syfte: Syftet är att ta fram en inköpspolicy som ska minimera årliga kapitalbindningen i lagret. Metod: Inköpspolicyn är utvecklad med hjälp av en blandad metod med fokus på den kvantitativa sekundärdatan med små delar av den kvalitativa primärdatan. Beräkningsmodellen består av de lagerstyrningsformler som presenteras i teorin. Med grunden från teorin och inläggen från intervjuer har forskningsmetoden varit deduktiv och följt riktlinjerna från Ali och Birley (1999). ABB Capacitors är fallstudien för detta examensarbete som modellen har blivit testat och verifierad hos. Slutsats: Examensarbetet resulterade i inköpspolicy som består av en beräkningsmodell och en artikelanalys som har visat sig framgångsrik från de teoretiska jämförelserna och det visar på att inköpsstrategin fungerar som tänkt. Matematiska modeller är bara verktyg i en inköpsstrategi, erfarenhet och kunnande är två komponenter vars betydelse inte ska förminskas. Svagheter i modellen rör kapaciteten i lagret eftersom modellens syfte är att minimera årliga lagerkostnaden genom att köpa in ur en ekonomisk synvinkel. Det finns en risk att den fysiska lagerytan tillåter mindre kvantiteter än vad som är optimalt. Modellen rekommenderas för tillverkande industrier.