سهام محموله موجودی: مورد صنعتی و تجزیه و تحلیل عملکرد

The “Consignment Stock” technique is a novel approach to the management of inventories in supply chains. It is based on an improved collaboration between the company and its suppliers, one that is acquiring growing importance in industrial environments, as the authors have found in Italy. The main aim of the present work is to describe the technique itself, thus underlining its potential benefits and pitfalls. The case proposed refers to a company manufacturing components for the automotive industry. Essentially, the company offered its suppliers the opportunity of stocking part of the items in its own warehouses, with the agreement that they would guarantee over time an inventory level between a set minimum and a maximum value.

There is no question that over the past decades an increasing amount of research has concerned the importance of establishing a profitable vertical relationship between companies and suppliers, especially in management literature. In particular, strong interaction and reliable collaboration between these two actors have emerged as strategic issues and powerful instruments for maintaining or acquiring competitive advantages in a dynamic and selective market. Indisputably, this issue also plays a pivotal role in inventory policies and management. Yet, despite the growing number of studies and theoretical models developed, the operational research still seems to be frequently divorced from industrial reality. Meanwhile, several practices that are not dealt with in the literature show up, acquire importance, and prove to be successful. This is the case of consignment stock (CS) management of provisioning, which, regardless of some similarities with the common (s, S) policy, reveals significant innovative contributions. Nowadays, this practice has been widely adopted in Italy, and is consistently gaining consensus among both small and large firms. Both business press and private sources have also confirmed recent CS applications between Italy and other countries. Under a CS policy, the relationship between a company and a supplier is based on the following simple rules: 1. The supplier will guarantee the company the continuity of an available stock between a minimum level s and a maximum level S: the stock will be stored in the company's raw material depots, close to the production lines. 2. The company may draw on raw materials daily, according to its needs. The supplier is paid for these materials according to their agreement, hypothetically up to a daily frequency, so that the information concerning the consumption trend is also constantly refreshed and immediately transferred to the supplier. In such a way, the continuous replenishment from the supplier protects the company against demand fluctuations and costs determined by eventual stockout may also be debited to the supplier, by means of contract penalties. On the other hand, the supplier has a better perception of his customer's requirements: lower stocking costs are incurred and the continuous evolution of market demand is directly perceived thanks to an electronic data interchange (EDI) interface. Several benefits are immediately evident: 1. The company always has raw material available. 2. The company pays for raw material consumption only when the items are drawn on for use. 3. The supplier saves holding costs and may organise his production in different ways, also with respect to eventual third parties. 4. A renewed and reinforced link is set up between the company and its supplier. However, CS requires the accurate definition of various parameters, i.e. s and S, and a constant attention to the information flow, that is, the electronic transmission to the supplier of item consumption. On this basis, the supplier can foresee the consequences of a better management of his own production, being freed from the bounds implicit in the strict EOQ practice (e.g. handling large but infrequent orders). This paper seeks to provide a coherent framework within which to understand the success of CS. We ask why these changes are taking place. Is it a mere coincidence that various firms are adopting CS policies or is there a rationale behind their choice? If this is the case, how should their choice be implemented? So as to grasp both the why and the how of CS, the rest of the paper is organised as follows. Section 2 briefly presents the main results of the literature, while Section 3, using the results of a computational simulation, shows how CS policy may outperform previous models. In other words, we provide a tentative proof that CS is a rational choice. Section 4 addresses the main tactical questions that follow the decision to adopt CS. This problem is tackled with the benefit of insights offered by a case study. Concluding remarks follow.

This paper gives the account of an innovative inventory policy called consignment stock. Its rapid diffusion and the absence of any important reference to it in the scientific literature led us to ask ourselves whether CS was just a fad or whether it had some value. We showed how, by combining the practicality of (s,S) policies with the “system approach” of joint-profit maximising models, CS is able to outperform the usual inventory models. Not only does CS allow savings in inventory costs, but it also entails several complementary intangible advantages, such as a higher degree of flexibility, an increased service level in turbulent environments, a reinforced and reliable relationship between companies and suppliers. Even Authors that argue that CS may be harmful for the supplier from a purely economic point of view, recognise the strategic importance of the relational rents stemming from CS ( Ferrozzi and Shapiro, 2000). Hence, the diffusion of CS has a clear rationale behind it, which at present we have shown by simulation experiments. Moreover, thanks to a case study, we have provided some insights into tactical issues that firms have to address once they decide to adopt the CS policy. We believe we have provided reasons that show why CS is catching on as well as how it is and should be implemented.