Air transportation of goods around the world offers fast turnaround for products for which speed of distribution and ground inventory reduction is important. But, compared to an ocean‐going container vessel, space on a cargo plane is limited no matter how big the plane is.
Unitised loads help maximise the loads that a plane can carry. These unitised loads usually consist of smaller loads packaged in carefully designed packing cartons, and stacked efficiently onto wooden pallets. The weight of wooden pallets can add a substantial amount of weight to the total load. However, in air transportation, the amount of space that wooden pallets take up presents the greatest source of inefficiency in the attempt to achieve optimum load density for products. Theoretically, if a material that does not take up as much space as wooden pallets is used, much higher load densities for products can be achieved, leading to savings in costs.
It has been shown during the last decade that using slipsheets in the place of wooden pallets has resulted in a much higher load density in the air transportation of cargo. One organisation which has implemented a slipsheet program for air freighting of their products is high capacity disk drive manufacturer Micropolis Corp. with distribution sites in the United States and Europe, and manufacturing facilities based mainly in Singapore.
Prior to adopting the slipsheet alternative, Micropolis' shipping method unitised the product three tiers high on wooden pallets. The palletised loads are then transferred to air cargo container shipping bases for loading into the cargo planes. The typical net payload of product in each unitised module was 932 pounds. The weight of the pallet added another 55 pounds. Allowing for the required clearances within the cargo bays, three tiers of palletised loads were possible.
The slipsheet unitisation method provided benefits to container shipping on the oceans, but it can provide even greater benefits for air freighting. Slipsheets weigh a mere four pounds and therefore add very little to the gross shipment weight. They take up a negligible amount of space under the unitised loads, are much cheaper than wooden pallets and are easier to dispose of.
Issues raised for consideration were:
- The need to equip forklift trucks with push‐pull attachments at the different points along the distribution chain. These included the receiving and shipping locations at Micropolis, and the freight forwarder at the airports.
- The need to train forklift truck operators to use the push‐pull attachments and on the practice of slipsheet handling methods.
- The need to provide resources to set up and manage the entire slipsheet program.
- The possibility of redesigning the packaging to best utilise the slipsheet handling method for maximum efficiency.
The concerns were overcome when Micropolis managed to get the agreement of the freight forwarders to purchase push‐pull attachments for their lift trucks and to train their own operators.
As a result of the slipsheet program, the number of tiers of product on each unit load was increased from three to four, without compromising any required height clearances. The load density increased by 33%. In terms of cost savings, Micropolis projected an annual net savings of US$342,000 based on current volume.
Reference: * Ebeling, C. W., "Slipsheets save weight and cost in the air", Transportation & Distribution, February 1992, USA