Laser Scanner Measures Package Dimensional Weight

May 6, 2009
The FS100 laser scanning system from FreightScanner uses a single laser to measure package dimensions and calculate dimensional weight for efficient freight packaging.

FreightScan LLC, (858) 436-8540,

Lincoln Laser Co., (602) 257-0407,

Engineers at FreightScan, Solana Beach, Calif., have developed Defined Imaging and Multiple Measurement (DIMM), a 3D laser-imager for static dimming — the process of measuring packages moved by skids.

When scanning up to four packages, DIMM calculates a length, width, and height reading for each package, along with its dimensional, or dim, weight. All scans are associated with a shipping order, so a shipment’s total dim weight can be calculated while individual packages are being processed.

To scan full shipments, the device uses a “skyline” mode to determine overall dim weight based on external dimensions of a pallet load. When gross weight exceeds dim weight, the shipment proceeds. But when dim weight is greater, the device alerts workers to dismantle the shipment so it can dim individual packages.

What is dimensional weight?
Dimensional weight is calculated by:

WDim = (l × w × h) × (1 / 194) where WDim = dimensional weight, l = length, w = width, and h = height. All dimensions are in inches.

The multiplication factor, 1/194 lb/in.3, is assigned by shipping companies that use dim-weight calculations for domestic shipments within the U.S. International shipments calculate dim weight by multiplying by 1/166 lb/in.3

Many carriers, including DHL, UPS, FedEx, and the U.S. Postal Service, charge shippers based on whichever is greater, gross package weight or dim weight.

Why dim weight? It lets carriers recoup the cost of shipping packages with low-volumetric weight that take up a lot of cargo room and keep trucks, ships, or aircraft from carrying their full weight capacity. About 33% of cargo shipped by air has a higher dim weight than gross weight, according to André Johnson, CEO of Freight- Scan, Solana Beach, Calif.

“This causes U.S. airlines to miss out on an additional $300,000 for every 10,000 tons of air cargo outbound at the average rate of $1/kg,” he explains.

The unit’s single, precisely positioned laser reflects off the cargo and back into the DIMM. The unit distinguishes reflected laser light from ambient light, removing interference and boosting resolution. The laser’s range-finding capability determines the distance to the package while laser raster scanning produces a digital image of the item.

FreightScan collaborated with Lincoln Laser Co., Phoenix, to refine and scale-up manufacture of DIMM under the product name FS100. Although FreightScan developed the initial design of the electronics, software interface, and hardware layout, Lincoln refined the working prototype for mass production. The company did this by boosting optical output by a factor of four, improving wiring and component placement, and redesigning the chassis.

FS100 completes scans in 4 sec and measures to within 1.0 in. In contrast, manual dimming of a pallet of packages can take 1.5 hr or more, according to the company.

About the Author

Jessica Shapiro

Jessica serves as Associate Editor - 3 years service, M.S. Mechanical Engineering, Drexel University.

Work experience: Materials engineer, The Boeing Company; Primary editor for mechanical and fastening & joining.

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