Answer

DCM BLO3001 Project P04 Group 6


Qns: Under what circumstance the mobile rack (as shown in your Blog) becomes a preferred choice instead of other storage system? Explain.


Ans: Mobile rack would be a preferred choice of storage system when the warehouse has limited storage capacity. Using mobile storage, the warehouse could better utilize the storage space. This storage system turn wasted aisle space into productive workspace and allows the storage capacity of the original workspace to be doubled. Powered mobile rack enable up to 80% of the warehouse floor area to be occupied. This greatly reduce space wasting.

Cantilever Racking

Cantilever Racks are meant for storage of long items such as steel bars, tubes and pipes. The “arms”, supported by columns, are used to hold these long items as shown in the picture. These arms are normally flexible in a way that the height of each row can be adjusted to accommodate for the load. Unlike pallet racks, it does not have the front column in the way, thus loads can be loaded and unloaded faster, minimizing handling time. Using this rack allows the locations of the loads to be more organized compared to when loads are piled together without the racking. It also creates space by having multiple levels, maximizing the use of warehouse space.

Push Back and Gravity Flow Racking

Similar to Drive-in and Drive-through racking, the Push Back Racking is able to better utilize warehouse space with the removal of lanes and aisle. In this type of racking system, pallets are loaded and unloaded from one aisle and each position is able to hold up to four pallets. Pallets are placed on wheel carts that roll on inclined frames. When a new pallet is being loaded into the location, the rest of the existing pallets will be pushed back into the storage lane. Goods will then be picked from the first pallet. After the first pallet is removed, pallets behind will automatically slide to the front due to the force of gravity.

Although Push Back racking system can increase pallet density which is ideal for warehouses, products that needs to be First-In-First-Out(FIFO) cannot be placed on such racking. Reason being, when a new pallet arrives and is loaded into the location, the rest of the pallets are being pushed to the back. It will then be impossible to pick from the earlier batches. Thus, this racking system should not be recommended to store products which have an expiry date.




In Gravity Flow racks, rollers are being used just like the Push Back racks. The main difference is that palletized loads are loaded from the back and being rolled to the front on rollers with the help of gravitational force. Goods will always be picked from the front and thus the First-In-First-Out (FIFO) rule is being observed. This eliminates the drawback of the Push Back Racking system whereby the FIFO rule cannot be carried out. Another benefit of this system is that pickers and forklifts will be accessing from different aisle as the picking of goods and loading of pallets will be on two different sides. This keeps the pickers a safe distance from the forklifts that are replenishing the racks.

Drive-in and Drive-Through Pallet Racking

This type of pallet racking has got vertical support frames with cross pieces at selected heights to hold the pallets. As shown in the picture, forklifts are able to drive in between the vertical support frames to retrieve or put a pallet. This greatly increases the space utilization of the warehouse as lanes and aisles are removed from the system. With this, up to 75% more pallets can be stored in the same space. However, stock selectivity is restricted as the first in will always be the last out (FILO).

The picture on the left is an example of Drive-in pallet racking. Forklifts can only access the products from one side of the racking.

This is a Drive-through system whereby forklifts can enter from both sides of the racking. This allows more flexibility since pallets can be accessed from both sides.

This type of racking is suitable when:

• The warehouse needs to store a large amount of the same product
• Seasonal good whereby input and output are at different times
• Pallets are dispatched in batches

Reason being, in those situations stated above, goods do not have to be First-In-First-Out (FIFO).

Double Deep Pallet Racking

Double Deep pallet storage is a simple adaptation of placing one row of 100% selective rack behind another. Using a deep reach lift truck, the operator places the back pallet into the system first, and then places another pallet in front of it. While selectivity has been reduced by one-half over standard pallet rack, twice as many pallets are stored for a given number of aisles. This increases productive use of floor space about 60% to 65%.

Double deep storage rack has become a very popular choice in "high throughput" operations. It offers low initial cost, high productivity, good selectivity and less equipment damage However, the disadvantage include the need to have double reach trucks, loss of absolute FIFO and poor visibility for the truck driver when accessing the rear location.

Adjustable Pallet Racking (APR)

Adjustable pallet racking is a pre-engineered rack construction system designed to meet a wide range of industrial storage needs and is one of the most widely used palletized storage equipment. This system is bolt free and can easily be adjusted. The racking system consists of two basic components – the frame and the beam. Frames and beams in this racking system can be used together in standard or modified form. Together with a number of accessories, it can produce an almost unlimited variety of storage solutions. The frames of the rack are constructed in a way that it is being welded and it comprised of two uprights alternate horizontal and diagonal braces and two base plates. Beams are usually manufactured from boxed steel section with beam connector brackets welded to either end. Beams fitted to frames are secured against accidental dislodgement by a locking pin inserted into the locking pin slot in each beam connector bracket. Beams are adjustable vertically; this basic adjustability cannot be varied.


Locking pins
In adjustable pallet racking, the frame and the beam is held together using locking pins. The locking pins are 3mm thick and zinc plated. The locking pin prevents accidental dislodgement of the beam and the shape of the pin is similar to that of a question mark. Two pins are used to secure each beam. The locking pin would not be vibrated out of position even if it were halfway out of the slot.

Eight cold-formed bends in the upright’s section give it exceptional strength-to-weight performance and excellent resistance to twisting Frame uprights are punched with a slot pattern that permits the insertion of beam connector brackets. The outside pair of slots on the upright is rectangular.

Advantages of APR:
-Beam height is adjustable for different pallet load heights
-The racks can be dismantled and moved.
-There is a random access to every pallet
-Damaged parts can be easily replaced.
-It is not expensive.

Disadvantages of APR:
-Low space utilization due to the reason that fork truck aisle give access to only two rows of racking.
-For racking above 8m in height, a chemically treated floor is needed to stabilize the racking with the load.

Powered Mobile Storage

Powered mobile racking features pallet racking fixed to bases that move electrically. Powered mobile racking maximizes space utilization, enabling up to 80% of the floor area to be occupied for storage. Powered mobile pallet racking comprises units of conventional pallet racking mounted on a steel framed base. The base is a diagonally braced structure; below which sit two bogies, with direct drive electric motors. The wheels run along a track set into the floor.
Varying rack configurations and bogie types are available to suit single bay loads of up to 15 tonnes and run lengths of up to 30 meters. Having no bolts eliminates the need for safety checks on bolt torque.

Up to 80% floor space utilization, each pallet supported, all pallets accessible, high throughput speeds, uses conventional handling equipment, and needs aisle control system.
It is particularly suitable for use in cold stores, high rental premises, bulky multi product applications, palletized consumer goods and food products. Mobile racking is expensive though this cost may be offset by a reduced building cost.

Conventional stationary storage units require space watsing fixed aisles.

Spacesaver storage systems turn wasted aisle space into productive workspace and allows the storage capacity of the oringinal workspace to be doubled.

Conventional Storage

Spacesaver Storage

Live storage

The live storage is design to allow the pallet load to be fed into higher end, and to be retrieved from the lower end. It is an expensive set-up and is only suitable for higher throughout per line item.


The benefits of implementing includes:
- Improved flow characteristics - less hang up
-Rapid adjustment without tools - reconfigure "in house" without havingto employ specialist labour
- Robust design provides long term durability
- Reduced installation times
- less disruption to warehouse operation

Basic Storage Method

There are two storage methods, namely the fixed storage location and random storage location.

For fixed location, every location has an assigned product to be stored. Meaning the products in the warehouse will always be stored at the same location. By using this method, it may be easier for workers to locate products as their locations will not change. However, this method has its limitations. Since each location will only be used to store specific products, there will be empty spaces when there is no more of the specific products to be stored at those locations. Other products cannot be stored at those locations resulting in wasted storage space. Thus, this method is not recommended in reserve storage areas in most of the industries.

This problem of having unutilized storage space can be solved by using the random storage location method. An example of a company using random storage location is NTUC Fairprice. The have large amounts of Stock Keeping Units (SKUs) going in and out of their warehouse everyday and could not afford to waste warehouse space by leaving locations empty. By using random location method, product could be stored at any empty locations. In this way, they will be able to better utilize their warehouse space, resulting in higher space utilization.

Companies should always consider the advantages and disadvantages of these two methods to choose a suitable method for the company.

STORAGE SYSTEM

This online e-learning session aims to equip students with the overview of the warehouse storage system. In this blog, we will be looking into the different methods in racking, storage and shelving system. The advantages and disadvantages of the above methods would also be explored. Apart from that, more in-depth discussions such as how a well-designed storage system contribute to the efficiency and productivity of the warehouse.