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Japan, the home country of Daifuku Co., Ltd., is the world famous earthquake country where earthquakes are daily occurrence. Daifuku has grown up its material handling business in such environment since 1937 and has accumulated expertise through several huge earthquakes marked in the history.
Why seismic tremor control is needed
Unlike the general image of earthquake, "collapse", we did not observe much damage to racks and rack-supported buildings that are designed in line with the safety and construction regulations. The major issues we observed are;
- 1. Damage of stored loads due to fall-off from pallets
- 2. Damage of material handling equipment due to fallen loads or pallets
- 3. Difficulty of recovery work on collapsed loads at high place
- 4. Loss from business interruption
To minimize such business risk, Daifuku sees it important to;
- 1. Minimize rack sway
- 2. Avoid load collapse from pallet
- 3. Avoid pallet fall off from rack
Where seismic tremor control is needed
According to USGS, other countries known as earthquake countries are China, Indonesia, Iran, Turkey, Peru, USA (Alaska, California), Italy, Chile and so on. When planning AS/RS in these countries, it is essential to think how to minimize the above mentioned risk.
Daifuku's seismic tremor control solutions
Daifuku offers varieties of seismic control solutions that can be applied alone or combined according to needs.
|Applied to||Solutions||Power of tremor|
|25~80 gal||80~140 gal||140~250 gal||250~400 gal|
|Quake-absorbing rack +
|Seismically isolated rack|
|Location control by stability|
1. Stretch-wrapping / Binding / Box pallet application
One of the effective ways to reduce the load turnover risk is to stabilize loads by stretch-wrapping, binding or roll box pallet application. However, it is not always possible to do so due to operational reason such as case picking requirement.
2. Fixed Stoppers at rack locations
Fixed stoppers installed in rack locations prevent pallet movement into crane aisle during earthquakes. They work effectively when combined with stretch-wrapping and binding. However, they cannot prevent loads on pallets from protruding or falling when stretch-wrapping or biding is not applicable.
3. Quake-absorbing Stoppers at rack locations
Quake-absorbing stoppers installed in rack locations absorb the collision energy and reduce load fall-off risk.
They can be applied to both newly built and existing racks.
4. Quake-absorbing Rack
Dampers installed at the top of AS/RS racks reduce energy of seismic activity by up to 50%, reducing the potential for loads to fall of the racks during earthquakes. Dampers can be installed on both existing and newly built racks.
5. Seismically Isolated Rack
A seismically isolated AS/RS base severs AS/RS from direct influence of earthquake tremors.
6. Seismograph / Seismometer
When the seismograph detects a significant tremor, the equipment controller sends cycle stop signals to all equipment to reduce the potential for damage.
7. Location control by stability
Ordinary random storage management places pallets in any available location. This means that tall, unstable loads may be stored on higher levels where the impact of earthquakes is greater. With load stability information registered, WMS can limit location assignment for unstable loads to only lower levels, reducing the risk of loads falling during earthquakes.