1. Introduction Inrecent years scholars have given meaningful reflexion to the integration oftransportation and inventory decisions. The target is find how to keep balancedinventory and low transportations costs.
World economy andtechnology are at the stage of rapid development, which increases therequirements as to the possibilities and demands. On the global market, thedemand for a variety of products and a short reaction time has increased whichresulted in enormous pressure to establish smooth and effective logisticsolutions. Important non-value added activities are warehousing and materialhandling. Holding a product on the shelf or moving them does not increase thevalue of the given product, but both are significant factors in a supply chainand play a crucial role in gaining customer satisfaction and making it possibleto obtain efficiency (Bartholdi and Hackman, 2012).Ganeshanand Harrison (1995) determine a supply chains as “a network of facilities anddistribution options that performs the function of materials procurement,transformation of these materials into intermediate and finished products, andproduct distribution to customers”.Warehousing,material handling and transportation allows you to configure the provider withthe customers’ requests, quick response for seasonal products, achieving theproduct’s compatibility, modify product or packaging and organization ofdistribution activities. Over time many companies have decided to set up theirsupply chain in order to increase the level of customer service and demandchangeability.
Customer service and logistic costs can be revised throughappropriate selection, storage and proper material handling. Thebasic idea of the magazine and materials handling is “it cost-effectivelyship products to the right place, at the right time, and in the right quantitywithout damaged or alterations” (Manzini et al, 2015). Warehousing andmaterials handling engage untying a large number of issues related with designand operational problems in manufacturing, distribution systems and economicsresearch. Establish the location of the warehouse and its design are strategicproblems which should be considered the first when creating many projects inthe supply chain.
Hence significant knowledge about size of the warehouse, oftentimesmeasured based on the amount, type and kind of storage space.2. Warehousecharacterizations.Inorder to obtain optimal conditions in the supply chain one should take intoaccount two types of decisions should be made. Constructivedecisions: location, capacity, and transportation channels. Coordination decisions: Supplier selection, partnership,inventory ownership, methods of sharing information, demand forecasts,production plans, inventory allocations, etc. All decisions are related to eachother and should be resolved at the same time with equal attention. Decisions regarding location have long-term effectsrelated to production, inventory levels and transport costs.
Its gives serious effects in influencing the supply chain. An example may be a good distribution network whichensures quick reactions. Each of the warehouse could be consider from threepoints of view: processes, resources and organization. According to Rouwenhostet al. (2000) materials arriving at a warehouse then are taken across a number of overtures named as processes. All of themeans, equipment and personnel needed to operate a warehouse is called asresources. Organization includes all planning and control procedures used torun the system. As a material/product is determined as a type of good, as anitem is called individual unit and connection of several items of severalproducts requested by customer is called a customer order.
The process in thewarehouse can be divided into several stages. The first is in order thereceiving process, when the products are delivered by truck or internaltransport. In this phase, the products may be examinedor converted and awaiting for the transfer to next step.
The next step after isstorage process where the items are allocated in storage locations. The storageare may be divided to the reserve area where the items are stored in mostfrugal way and the forward area where are easy to pick for the order. Orderpickingrelates to the movement of the items from storage location.
As the last is theshipping area where orders prepared, checked awaiting for loading.Fig. 1 Typical warehouse functions andflows (Tompkins et al. 2003). The warehouse resources include personnel from whichdepends the work in the warehouse and is one of the most important resource.
It’s also included the material handling equipment which is used to prepare theshipment like sorter systems, palletizers, truck loaders and other equipmentwhich supports the orderpicker defined as orderpick auxiliaries, for examplebar code scanners. Warehouse management system – computer system- use tocontrol the processes. The movement of the items could be performed manually orusing pick equipment like for example reach truck. The warehouse resourcesinclude as well the storage unit where the product could be stored likepallets, carton boxes etc. and the storage system which could be the set of theshelf or fully automated conveyors.The last to describe is the warehouse organization. Onthat part is included important decisions concern the process flow at thedesign stage, how the area will be segregated in the warehouse, for examplewill the picking area be divided to zones for only sorting or picking thebatches or will be use the separatestorage and retrieval aisles.
At this stage, a policy should beestablished according to which the process flow will take place. Policiesshould contain information about:- review at the receiving process which establish theallocation of truck to docks;- At the storage process, are items transported to storagesystem and are allocated to storage location, then will the storage spaces bededicated for one type of the items or divided to specific item groups. It hasto be prescribe where will be allocate the most often items, how the stock willbe replaced.- At the orderpicking process will that be assigned for oneor maybe more pickers, will have the zones divided depending on the type oforders and how many times in the routing the location has to be visit.- After all assigned the responsibilities and task to thepersonnel and equipment. Fig 2. Framework for warehouse design andoperation issues.
(Riccardo et al., 2014) 3. Warehousedesign.Whiledesigning a warehouse, many related factors must be taken into account. Designingthe warehouse takes place in succession of the following stages :”(…) concept,data acquisition, functional specification, technical specification, selectionof means and equipment, layout, and selection of planning and control policies.
” (Rouwenhostet al.,2000). Thesedecisions can be divided into strategic, tactical and operational ones. Functionaland partly technical specification will include decision related to the processflow and the level of automation. Choice of the storage systems anddimension/layout of the warehouse are tactical agreements. Control policies preciseas to details should be discussed on the operational level. During designing a warehouse the criteriahave to clearly define.
The relative importance of the criteriondepends on the type of the warehouses. There are two types of magazines: thedistribution warehouse and the production warehouse. In both cases, the following criteria willbe considered: investment cost and operational cost, performance and bandwidth,storage capacity, time of implementation and order quality accuracy. Storingproducts and filling out external customer orders, usually consisting of alarge number of order lines (where each order line determines the amount of onespecific product) that’s the function of the distribution warehouse. The numberof products can be large, while orders can be small, which can result in highercosts orderpicking process. Often, such warehouses are modified tominimize the costs associated with picking the orders. An outstanding criterion is to get thehighest possible throughput of the warehouse with the lowest possibleinvestment and operating costs. Often, the combination of the requiredbandwidth and the short waiting time results in the decision to transform thewarehouse into a more automated one.
It is obvious that the costs increase withthe level of automation. Storage of the raw materials, work in processlinked with a manufacturing these are functions of the production warehouse. Finishedgoods and raw material may be stored for a long period of time. Thisis the case when the delivery of materials exceeds the order quantity.
A longperiod of time causes that storage of materials becomes expensive. Most oftenthe material is stored in large quantities in an inexpensive system such aspallet. One of the important criteria in this situation isstorage capacity. Primary target is to design a warehouse with usage of lowcost expenditure. The situation with the storage of work in process looks abit different. In order to avoid stopping the production the all of thetransactions have to complete fast. It can cause the determinant between thetime of establishment and the order fulfillment will be one of the maincriteria when designing the warehouse. The storage of products has a strategicrole in the supply chain: an efficient organization of products in appropriatelocations enables these products to be moved faster inside the warehouse andlogistics channel, which increases the speed of delivery and thecompetitiveness of enterprises.
For a company to be competitive on the market,it needs a warehouse with a high capacity located in a strategic point.When deciding on the location, thecompanies should ask themselves for a questions like how many warehouses shouldbe created, where they should be located in order to quickly respond to thecustomer’s orders and satisfy its demand, while minimizing costs (Melachrinoudiset al., 2000). While making decisions, the firms should not focus onlyon the investment costs but also on how much local incentives and transporttimes will affect them investment. Planning the number and location ofwarehouses and distribution centers is determined on the basis of creating themost optimal supply chain network. In the case of a well-organized supply chainand distribution of warehouses and distribution centers in strategic positions,a permanent network is created. The advantage of this is the lack of materialaccumulation in the storage or shortage of it, production capacities arerelated to its resources, warehouse capacity and distribution centers arerelated to the inventory they handle, and transport costs are the actual costincurred and included in the whole process from raw material to fulfillment oforders. .
As a strategic place isdefined easy, fast and access to a variety of suppliers, spatial distributionin relation to the producer and the recipient, raw materials should be storednear their production and purchase finished product warehouses should belocated in centres of consumption demand, taking into account such factors as,for example, the range of goods, the density of the retail network and thefrequency of purchases. Existence of access roads ensuring convenienttransport, utilities (water supply and sewage, electricity, telephone), and theability to arrange buildings in a way that ensures free entry, access, accessto the ramp/bays.Allefforts made to gain a competitive advantage can be frustrated by one decision- to build / rent a large / small warehouse space. How to calculate thewarehouse area in relation to the scale of our business for a given timeperspective or what size (scale) of our business can be implemented with theexisting warehouse space. The size and shape of the warehouse depends on thetypes of materials stored there, and in a more general sense, on the profile ofthe company’s activities in the industry (warehouses of the automotive industrydiffer significantly from the cosmetics / pharmaceutical or bulk materialsstores). The management boards of the companies and / or logistics managers relativelyoften have a serious “warehouse” dilemma to consider: to build orrent, expand or not, move to a new warehouse or get rid of excess space.Regardless of what question they ask, something always boils down to two issues- the design of a new warehouse or the assessment of the surface resources ofthe “old”.
Assortment items or product codes represent all productsstored in the warehouse. Having knowledge about their quantity is important toensure the appropriate number of storage places for different types ofproducts. As order picking takes place in a certain area of the warehouse, thespeed with which you can reach selected products will determine the efficiencyof the facility’s operation. The greater the distance between storagepositions, the more work will be consumed by the confection process. Questions to answer when planning a newwarehouse are: “How many pallets are we currently saving?”,”What is our growth rate” and “How many pallets will we store ina year or two?” An analysis of current and future needs is one of the keyelements that should be considered during this type of projects. Thefacility layout plays an important role in the business success of the company (Johnston,1995).
However, regardless of the situation, the overall layout of the facilitymust be compatible with a good storage system, i.e. a system that meets thefollowing needs: the best use of space, minimizing the trans-shipment of goodsto the minimum, ease of access to the stored product, maximum possible rotationrate, maximum laying flexibility product and easy control of the quantity ofstored goods. The following zones should ideally bedefined in the design of the warehouse and its layout:A.
Loading and unloading zones.B. Reception area.C. Storage area.D. Order picking area.E.
Shipping zone. 4. Conclusion.When designing a new warehouse, it isnecessary to identify the needs, possibilities and expectations related to thenature of the company, the quantity of the assortment held and its rotation.Knowledge of the number of items in the assortment, the number of palletsstored, the number of orders packed per day or the number of pallets that makeup one order is essential when designing a new warehouse. This knowledgeenables us to develop the space efficiently and in accordance with theprinciples of material flow.