Principles of warehouse layout and operation

During the consideration of planning layout and operations in any warehouse system, there are fundamental principles embody a general philosophy of good pratice.


Load utilization









A unit load is an assmebly of individual items or packages, usually of a same kind to enables convenient composite movement (mechanical or manual movements). typical unit load sizes are wooden pallets, roll cage pallets, tote bins, post and cage pallets and ISO containers.


Advantages

1. Moving a greater quantity of goods per journey, reduced numbers of journeys required. Hence total cost is also reduced.
2. Enabling a better use of warehouse space.
3. Enabling a use of standard handling system and equipments.
4. Increase the speed in loading and unloading time
5. Minimise the risk of damage and pilferage.

Better use of space

It is important to make the best use of space when planning and operating a warehouse. An effective space utiliztion makes good use of total volume not just the floor area.

Considerations of good space utilization includes

1. Not holding obsolete stocks
2. Minimise total stock, compatible with customer service
3. Fully utilizing head room
4. Using mezzanine floors
5. Minimising gang ways compatible with safe movement and access to stock
6. Careful positioning of services, pipes etc
7. Using random stock location system rather than fixed location system

Minimise movement

System planning and operation should aim to minimise movement and movement cost

To achieve:

1. Locating close together those parts of a system between which there is a lot of movement
2. Locating the most popular stock lines to minimise travel distance
3. Separating order picking stock from reserve stock area
4. Using appropriate unit loads
5. Using equipment designed to eliminate personnel movement
6. Using computerized techniques for determining goods and people movements
   

When deciding a layout, there may have to be a compromise between minimizing movement and minimising congestions, while avoiding consequent risk of accident or slowing down of operation

Controlling movement and location

Control is very important in warehousing. It concerned with movement and the awareness of where the material is located within a system. The ability to control a system, to have rapid and accurate data on location and system status, enable management to run a warehouse effectively, to respond quickly to changing situations and customer request.

Reflection from ALB trip by Winnie

To itemize the individual reflection on field trip to ALB (Army Logistics Base), the type of warehousing floor layout at ALB is Through-flow. Through-flow occurs when the loading bay facilities for outbound and shipping are separated at opposite end of a warehouse building. ALB uses the Through-flow to reduce the confusion between goods in and goods out and to let all goods travel the full length of the warehouse building. The other reason for using Through-flow is the goods inward vehicles and dispatch vehicles are very different in platform height and nature of unit load. It necessitates to control for easy and flexible operations and for future building expansion. The height of the each floor of ALB building is thirty meter height that is the same height of ten stories. The powered mobile racking system is the main storage system of ALB and stores homogeneous products. The layout consists of a number of mobile sections working between fixed and racks. Mobile racking provides good space utilisation, random access to every pallet and suitable for stock where the number of line items is high. Installing cost for the system is expensive although it can help to reduce building cost and consequent on the better space utilisation.
We saw the vertical carousel system at medical supplies. In the vertical carousel system is a series of shelves suspended between two continuous chains are driven through supporting sprockets to move the trays up or down as necessary. The carousels can be built to use the available building height. Spared parts are the MHEs used at the inbound and outbound of ALB. At ALB, the laser guided vehicles are used in the distribution centre.

the throughput level

In addtion to the through flow and the U flow, good A has the highest throughput level. hence it's located nearest to the aisle, the marshelling area and also the cross docking area. Then it follows by goods B, C, D, E and others.

THROUGH FLOW

The above diagram shows a through flow of goods in a warehouse

Similarly, it consists of 5 main areas as the U flow. The major difference between the 2 flow is the location of the loading and unloading bays. For through flow, the loading and unloading bay is located at different part of the building, often at oppostie end of a warehouse.

Advantages

1. Reduce risk of confusion between goods in and good out
2. Able to meet the requirements of very different good inward and dispatch vehicle in terms of platform height and the nature of unti load.
3. More useful and applicable to warehouse which connects with its production plant

Disadvantages

1. Necessitates all goods to travel full length of the building
2. Lesser environmentally control
3. Less flexible
4. Harder for future building expansion

In addtion, the ABL we visited is a through flow designed warehouse.

U FLOW

The above digram shows a U flow of goods in the warehouse.

There are 5 main areas:
1) Goods in (receiving dock area)
2) Main store (reserve storage area)
3) Order picking (forward storage area)
4) Marshalling (conveyor lines area)
5) Goods out (shipping dock area)


The flow of goods appears to be an U flow design as the loading and unloading bays are located as the same side of the building. The goods coming from receiving dock, unloading, put away to reserve storage area, break-bulk and replenish to forward (active) storage area, conveyor lines to shipping dock.

Advantages

1. Minimise the movement of goods by locating fast product lines close to the loading bays.


2. Due to it's design, it has better utilization of dock space and associated handling equipments


3. A possibility that it requires lesser total area with seprate loading and unloading bays.


4. More flexibility. Enables expansion in 3 other directions.


5. Better control of security and environment.

Disadvantages

1. Higher risk of confusion of goods between goods in and goods out.


2. Unable to meet different docking requirements between goods in vehicle and dispatch vehicle.

http://www.youtube.com/watch?v=NkfHVYv5nUo&feature=related

Above link will give you a better understanding in the 5 main areas of a warehouse operation.

Army Logistics Base Trip by Jasmine

28 November 2008 I joined my class and board the coach at Temasek Polytechnic. We headed to the Singapore Army Logistic Base (ALB) at Chua Chua Kang for our DCM one and only field trip.




The ABL is Singapore’s first centralised logistic base. The warehouse space is about 34 hectares of land or an equivalent of 45 football fields.
The Army Logistic Base (ALB) is jointly developed by the Singapore Armed Forces (SAF), the Defence Science & Technology Agency (DSTA) and Singapore Technologies Logistics.


In recent years, the private sector logistics operators have focussed on greater integration with its suppliers and third party logistics agents to further optimise its supply chain. Hence the development of the ABL is built and operated on a novel Design, Build and Operate concept whereby the commercial contractor, Singapore Technologies Logistics, is not only responsible for the warehouse's design and construction but also its full operations for the contractual duration.

By working with ST Logistics, the Army is able to tap into the ideas of the latest commercial best practices. ALB have clocked a labour productivity improvement of 25% and an 80% reduction of stores collection time during mobilisations. Annually, the base will also save the SAF about 25% in warehouse management fees.


In this dynamic logistic based, to achieve high productivity, effectiveness and utilisation, they use high technologies such as RFID, multi-storey warehouse architecture including an Automated Storage and Retrieval System (ASRS), a Mobile Racking & Shelving system, a modern wireless radio frequency identity system, Automatic Guided Vehicles, and Vertical Carousels.

This field trip was enriching and exciting as it was my first time to visit a real warehouse. It definitely enhanced my understanding in distribution centre management!

Constraints of Layout Designs

Warehouse space & sizing is a critical aspect of planning a new facility or re-designing an existing building.

Many times organizations start from a fixed view of what size the facility will be, and most times the square footage is based on affordability. The problem with this, is that the building may end up be to big, and therefore more expensive or too small and put operational constraints into the facility before the design even gets off the ground.

Warehouse layout and sizing: The correct way to size the facility is from the inside, that way the actual size required will fit the operational requirements, and will ensure that all available space is used and you are not paying for unused space.

Estimating space requirements: Short and long term, based upon forecasts, historical usage patterns, and projected changes. Developing new layouts to maximize usage of space. Short- and long-range sizing of individual areas: racks, shelving, automated systems, docks, staging, offices, and support.