Arrigo Pareschi

TPM: situation and procedure for a soft introduction in Italian factories

Personalization of products, mix variability and short time to market are the most important factors that have forced companies to a new form of organization during past years. A very common reply to this question is a lean organization based on flexibility of productive lines, reduction of storage and integration among company sections. In this context, quite differently from a traditional system, the maintenance function must work efficiently. Also the maintenance division must contribute to the success of the factory. Aims to introduce a methodology for a soft and tenable application of the principles of total productive maintenance (TPM) in Italian factories. The first step of the study is an explanation of the actual situation, usually based on traditional or on productive maintenance. After a brief introduction, focuses on TPM links with productive maintenance in order to suggest a method for TPM. Concludes with a real application of TPM in a big factory, with a description of a world leader in plant manufacturing for the ceramics industry.

Similarity-based storage allocation rules in an order picking system: an application to the food service industry

Todays distribution warehouses often need to process a far higher volume of smaller orders of multiple products which considerably increases logistics costs. They use the so-called order picking (OP) systems where products have to be picked from a set of specific storage locations by an OP process usually driven by production batches or customer orders. The OP is often very labour-intensive and its efficiency largely depends on the distance the order pickers have to travel, which therefore needs to be minimised. Minimising this distance is affected by several factors e.g. facility layout, shape of storage area, and especially the storage assignment strategy. Products that are frequently ordered together in multi-item, less than unit load customer orders should be stored near each other: this is the correlated storage assignment strategy. This study develops, tests and compares a set of different storage allocation rules based on the application of original similarity coefficients and clustering techniques. Lastly, a case study demonstrates the effectiveness of the proposed rules in minimising logistic costs.

The threshold value of group similarity in the formation of cellular manufacturing systems

Cellular manufacturing is an effective alternative to batch-type production systems where different products are intermittently produced in small lot sizes with frequent setups, large in-process storage quantities, long production lead times, decreasing throughputs, and complex planning and control functions. An effective approach to forming manufacturing cells and introducing families of similar parts, consequently increasing production volumes and machine utilisation, is the use of similarity coefficients in conjunction with clustering procedures. In a similarity coefficients-based approach, the results of the clustering analysis depend on the minimum admissible level of similarity adopted for the generic group of clustered items. This is the so-called threshold value of group similarity. The aim of this paper is to identify effective values of the threshold value of group similarity to help practitioners and managers of manufacturing systems form machine groups and related part families. The proposed threshold values for a given similarity coefficient are based on calculation of the percentile of aggregations generated by the adopted clustering algorithm. The importance of the proposed measure of group similarity has been demonstrated by experimental analysis conducted on a large set of significant instances of the cell formation problem in the literature. This analysis can also support the best determination of this percentile-based cut value especially when the number of manufacturing cells is not known in advance.

Redesign of the Mozzarella cheese production process through development of a micro-forming and stretching extruder system

Abstract The aim of this paper is the analysis and examination of the industrial processes for Mozzarella pizza cheese (hereafter referred to as pizza cheese). Specific phases and mechanical devices are studied in order to optimise and rationalise the production cycle. This goal is reached by developing a new and innovative forming method. At present pizza cheese is produced in 1–5 kg pats whereas, as this paper intends to highlight, by forming the cheese in smaller-sized dimensions (5–10 g) the processes will benefit in terms of energy consumption and use of resources (equipment, water, time etc.). Another advantage would be that the customer would be provided with a ready-to-use product, without the need for additional cutting. The paper deals with an innovative process for pizza cheese production, by focusing mainly on the forming phase; a double-screw extruder with a productivity of 20 kg/h was designed and tested in order to evaluate its functionality and applicability. The most relevant spin-offs deriving from the new forming device are the elimination of the pre-hardening phase, the reduction of the chilling time of about 10-fold, the reduction of the total processing time of about 25% and the diminution of the refrigerant water consumption.

Logistics outsourcing: an examination of third-party providers

The outsourcing of logistical functions to third-party providers has become an increasingly powerful trend in modern multinational companies. The literature presents several studies on the outsourcing of logistical activities by contractors, the greater proportion of which focus on industrial and service companies. In contrast, there are only a few studies on providers who offer logistical services. A survey of several managers from logistics service providers operating in different industrial sectors and countries was designed in order to accept or reject a set of hypotheses collected from previous studies found in the literature. The database was analysed by applying statistical modelling and inferential analysis, which are based on the Pearson chi-square test, Kruskal-Wallis test and the calculation of exact p-values. Not all results are consistent with previous findings.

Correlated Storage Assignment and Iso-Time Mapping Adopting Tri-Later Stackers. A Case Study from Tile Industry

The process of picking products from storage locations to fill customer orders is a very critical and labour-intensive logistic activity, especially in the presence of many orders made of a few orderliness. The storage strategy is one of the main factors affecting the order picking system performance. Object of this chapter is the development and application of an original and systematic procedure for the minimisation of the variable travelling cost in a picker-to-part high-level order picking system with tri-lateral stackers. This procedure takes inspiration from a correlated storage assignment strategy developed and applied by the authors, and is based on the introduction of similarity indices, as measures of correlation between products, the application of hierarchical clustering algorithms and positioning rules. The authors propose different storage allocation/positioning rules supported by an iso-time mapping of the storage area. A case study from tile industry is illustrated and the results of a what-if analysis are discussed.

Numerical solution of the navier-stokes equations for a rotating fluid flow in a cylindrical pipe

SommarioIn questa nota si presenta uno studio numerico del moto di un fluido viscoso ed incomprimibile in un tubo cilindrico, chiuso in uscita da un disco ideale poroso rotante, che trascina e mantiene in rotazione il fluido che lo attraversa. Si è adottato il suddetto modello per rappresentare la prerotazione diretta che ha luogo nel tubo di aspirazione di una pompa centrifuga. Si è determinato il campo di velocità per via numerica attraverso la soluzione diretta delle equazioni di Navier-Stokes in forma completa fino a valori del numero di Reynolds tangenzialeRet pari a 5 000. I risultati numerici danno un quadro dettagliato e completo delle principali caratteristiche di tale tipo di flusso, e, confrontati con risultati sperimentali disponibili nel campo diRet turbolento, mostrano un significativo accordo qualitativo. Si riporta infine un confronto con i risultati di precedenti indagini numeriche sul moto di fluidi rotanti presenti in letteratura.SummaryA numerical investigation of a viscous incompressible rotating fluid flow in a circular cylinder with a net axial flow rate is presented. The cylinder is opened at the bottom and closed at the top by an ideal porous rotating disk, through which the incoming fluid flows receiving an action of solid body rotation. This physical model has been chosen for a realistic representation of fluid direct prerotation which takes place in the suction pipe of a centrifugal pump. The flow field was solved by the direct solution of the complete Navier-Stokes equations for values of Reynolds tangential numberRet up to 5 000. The numerical results give a detailed and complete sight of the principal features of such kind of flow, and, compared with experimental results in the turbolence range ofRet. show a significant qualitative agreement. A comparison with previous numerical investigations of other authors about rotating fluids is reported.