Warehousing

Chapter V                                                            

Inside the warehouse:                                                    Jnayni Zakaria

Design and flow:

In order to optimize warehouse design and location, companies trend to use simulation software in their planning. Actually There are five principles in designing a warehouse:

1. Unitise loads: Products should be handled in modules or units to reduce handling costs and improving handling efficiency by carrying each module as a single unit through the logistical system without dividing it, which will improve the storage and minimize the journeys.
2. Maximise cubic space utilisation: It is desirable to utilise as much space in the warehouse as possible. The factors influencing this principle are the tradeoffs between cubic utilisation or warehouse density and accessibility, speed of throughput, and the need to minimise double-handling; and the choice of preferred storage location systems: fixed, hybrid, zone and random.
3. Optimise warehouse height: Higher warehouse buildings achieve scale economies in warehouse construction using ‘clad rack’ or ‘roof on rack’ buildings; use land more intensively; and use automated storage and handling systems.
4. Minimise internal movements: Moving inventory less is efficient in terms of cost and time. And that can be achieved by the application of popularity storage whereby items with high activity; the design of layouts and flow to minimise movement, avoid congestion and separate storage and picking; and the use of technology and information systems and the use of mechanisation.
5. Provide a safe working environment: It can be achieved by the elimination of hazards, such as separating people from moving equipment, providing a formal risk assessment process and training in using transport, racking systems and machinery, reducing manual handling to avoid cumulative strain through the use of lifting equipment.

Warehouse racking:

The purpose of racking is to store loads vertically and reduce the floor space required. To select a rack configuration we take in consideration the initial costs and the operational costs such as rack and product damage, product expiration. Load characteristics such as weight, physical dimensions and  pallet type and condition are important. And other factors like the type of lift equipment, the design and layout of the building.

Types of racking

1. Block stocking of pallets: refers to unit pallet loads stacked on top of each other and stored on the warehouse floor in lanes or blocks. They are stacked to a specific height based on a number of criteria such as pallet condition, weight of the load, height clearance and the capability of the warehouse forklifts. The pallets are retrieved from the block in a last-in, first-out (LIFO) manner.
2. Adjustable pallet racking (APR) is a highly versatile storage option and gives direct access to individual pallets without specialist handling equipment. It is particularly well suited to storing a wide variety of items of different sizes, weights and types, and high turnover operations where fast access to products is needed.
3. Very narrow aisle (VNA) racking enables high-density storage by making use of the warehouse floor area and roof height. VNA can reduce aisle width by up to 50 per cent compared with standard aisles and is particularly well suited to pallets of a uniform size and warehouses with a high roof and a flat floor. Pallets can be reached only by specialist equipment, which is costly but helps to protect the security of your stock. VNA aisle trucks are guided by rail or wire systems, so the risk of rack damage due to collision is reduced, as are maintenance costs.
4. Drive-in racking gives access to just one side of the aisle, so it operates on a first-in, last-out (FILO) basis. Drive-through racking gives access to both aisles using a FIFO stock-rotation system. This Is limited, however, by the need to empty lanes at every level.

Drive-in and drive-through Racking are particularly well suited to low turnover products with a high number of pallets Per SKU, cold storage, including chilled and frozen, and high-density storage of easily damaged or fragile items.

1. Mobile racking is comprised of standard racking mounted on motorised, mobile bases. This enables increased storage capacity by eliminating most aisles and block racking, without restricting access. Mobile racking is particularly well suited to cold storage – both frozen and chilled – space maximisation where order picking isn’t a major concern, and batch storing pallets or other heavy goods that all need to be accessed at the same time.
2. Pallet live racking allows the loading of stock in one aisle and removing it from the next. A FIFO system allows automatic stock rotation. Each lane is usually dedicated to storing one product variant or for marshalling loads in or out. Pallet live racking is particularly well suited to goods with expiration Dates that need failsafe stock rotation, a relatively small number of SKUs in a high quantity Of pallets, and fast-moving ranges where items need to be retrieved at speed.

Warehouse materials handling equipment

There are various materials-handling equipment (MHE) types, selecting a MHE type is one of the important keys to improve warehouse’ operations.

1. Hand pallet trucks suitable for low volumes over small distances, are inexpensive and are suitable for palletised loads. They are often carried on vehicles to help offload palletised trailers. Power pallet trucks are available in pedestrian, stand-on or rider versions. They are designed for truck loading/unloading and pallet transfer duties to and from receiving/despatch and storage areas.
2. Forklift trucks (FLTs) are the most ubiquitous and versatile of mechanical handling equipment. A basic forklift can be used for handling standard pallets and a clamp adaptation for lifting and stacking of bulk products such as fridges. FLTs are of moderate cost, are versatile and can be container compatible. They are excellent for loading/unloading operations and transporting product over moderate distances.
3. Narrow aisle reach trucks are used for warehousing duties in narrow aisles from  2.7–2.9 metres and are side-seated operated. The load is retracted for travelling, reached forward for stacking. Narrow aisle reach trucks are typically 1–2 ton capacity with lift Heights of 9 metres, however, they are not suitable for outside use and not good for travelling with loads over long distances.
4. VNA systems permit the narrowest working aisles for high-density storage. They enable maximum stack heights on racking while maintaining 100 per cent load access, high work throughput rates, and flexibility. With up to 2 tonnes capacity and lift heights of 12 metres, they typically work in aisle widths of 1.85 metres.
5. Other specific equipment types include side loaders, stacker cranes, automatic guided vehicles (AGVs) and conveyor systems.

Technology and warehouse management systems

The concept of whole life cycle cost (LCC) is the best way to calculate the real cost of any warehouse equipment, the total LCC of any equipment consists of three main elemnts :