Knowing the weight and volume of products, packages and unit loads can be helpful in determining the best way to store, handle and ship them. That's why weighing and cubing equipment, from simple floor scales to laser-based dimensioning systems, is such a common sight in warehouses and distribution centers.

Simply determining how much an item weighs requires nothing more than a basic bench or floor scale.

Bench scales, which work like typical bathroom scales, are used with items that weigh 200 pounds or less, says Don Halbert, global product manager for Avery Weigh-Tronix (877-888-1646, www.wtxweb.com).

Larger items are usually placed on floor scales. These high-capacity scales can be recessed into the floor or surrounded by ramps, Halbert says, allowing lift trucks and pallet jacks to drive onto them. More basic designs sit above floor level and require lift truck drivers to deposit loads for weighing and then pick them up again.

These scales are often located near the receiving dock to monitor inbound inventory. They can be used to ensure the weight of incoming packages and pallet loads matches the declared weight or to ensure unit loads are within the weight limits of the racks where they'll be stored.

At the shipping dock, scales are used to document the weight of outgoing freight or to confirm that returnable containers are empty before they're sent back to a supplier.

Many of these processes can be made more efficient, Halbert says, by integrating scales with materials handling equipment such as lift trucks and pallet jacks. Equipping a pallet jack with a scale, for example, saves operators the time and effort of walking to a dedicated floor scale to weigh loads between operations.

Adding more sophisticated instrumentation to a scale allows it to do much more than report an item's weight. A counting scale, for example, can perform calculations that simplify the process of taking physical inventory.

A worker tasked with taking inventory of small components can place a sample of those components (Halbert suggests five pieces or more) on a counting scale, and the scale will calculate the average weight of a single piece. The worker can then place the entire inventory of that component on the scale, and the scale will quickly determine the total number of items.

The precision of the counting, Halbert says, depends on the sensitivity of the scale.

Scales built right into storage shelves and integrated with a company's inventory software can make this process even easier, says Jerry Stoll, warehouse market manager for Mettler-Toledo (866-450-2801, www.us.mt.com). This new “smart shelf” technology, he says, can continuously count inventory and automatically trigger re-orders, saving labor in the backroom as well as on the warehouse floor.

Scales with sophisticated instrumentation are also used for quality assurance. Check weighing scales are used in pick-and-pack operations to compare the actual weight of a finished package against the known weights of the items in an order. If a package weighs significantly more or less than it's expected to, it's diverted for a quality audit.

Check weighing is often performed in motion by scales that are integrated with a conveyor system and a bar code reader. These high-speed systems often interface with warehouse software systems and automated sorters.

According to Halbert, in-motion check-weighing systems can be configured several different ways. Weight sensors can be added to the legs of a conveyor system, or a whole section of conveyor can be placed on a floor scale. The checking calculations can be done by the scale's electronic instrumentation or by the host computer system.

Simply determining the weight of a product or package has become less important in recent years as many operations have become volume-based rather than weight-based. Recent changes in the way parcel carriers charge for ground freight provide the best example of this shift.

FedEx, UPS and other parcel carriers used to calculate charges for ground freight based on a package's weight. Under this system, however, carriers felt they were undercharging for large, lightweight packages that took up considerable space in their trailers. To solve this problem, all the major U.S. parcel carriers changed their pricing last year to take the volume of a package into account.

The new pricing systems are based on dimensional weight (often called “dim weight”), which is currently determined using the following formula for domestic shipments: (length x width x height)/194. The carriers charge customers for the dim weight of a package if it's more than the package's actual weight.

Determining the volume of a package can be done using a tape measure and some simple math, but automated equipment can speed up the process significantly.

Dimensioning equipment—also called cubing equipment—is nearly always combined with a scale, allowing users to simultaneously determine the weight and the volume of a package or product.

Dimensioners use ultrasound, infrared light and/or lasers to sense the dimensions of a package.

Ultrasonic dimensioners are reliable and economical, but their accuracy suffers when they're used on odd-shaped items, says Randy Neilson, director of sales and marketing for Quantronix (801-451-7000, www.cubiscan.com), manufacturer of CubiScan dimensioning products.

Infrared dimensioners are also reliable and economical, he says, and they're better at measuring odd shapes. Their accuracy, however, depends on their quality and design.

Laser-based systems are very accurate, even when dealing with irregular shapes. Laser dimensioners are the most expensive systems to buy and maintain, Neilson says, and some laser systems don't work well with dark-colored items that absorb the laser light.

Which dimensioning technology you should choose, he says, depends on the specific needs of your application.

Like scales, dimensioners can be designed to handle stationary products or products in motion.

Static dimensioning systems require an operator to place items onto the dimensioner, and they're usually used in conjunction with a handheld bar code scanner.

Small, portable static dimensioners can sit on a desktop or a mobile cart (see illustration below). An operator places an item onto the bed of the dimensioner, presses a button, waits a few seconds for the measurement to take place, and then removes the item.

Large static dimensioners for measuring pallet loads usually sit on the floor near the dock, and they're often mounted above a floor scale. A lift truck operator places a pallet load onto the scale, backs away while the measurement takes place, and then retrieves the load.

In-motion dimensioners are integrated with conveyor systems and automatic identification equipment to capture the dimensions of packages or palletized loads as they travel through a facility.

In addition to measuring the dim weight of outgoing freight, cubing systems can also be used to measure the volume of incoming inventory. A warehouse management system (WMS) can use this volumetric information to determine the most efficient place to store inventory, says Neilson. This information can also be used in pick-and-pack operations to allow the WMS to determine the best carton size for an order.

In addition, says Neilson, many retailers also require suppliers to provide volumetric information about their products. Retailers use this data to efficiently allocate shelf space for merchandise in their stores.