How to automate lift trucks

By retrofitting standard lift trucks with an automation kit, productivity can double and operators can be used more efficiently.

It's becoming a classic Catch-22 for material handling and logistics managers. They need to increase distribution center productivity to keep labor costs under control but, in many cases, they're also being forced to cancel or postpone capital investment. For many companies this squeeze has ruled out the possibility of using automated solutions such as automated storage and retrieval (AS/RS). Some have been looking into using their existing equipment to reduce the investment required to automate warehouse operations.

One such alternative involves equipping standard lift trucks with automation kits so that the trucks follow the operator to each picking location and deliver the pallets to dispatch when full. Lift trucks automated in this way can also perform other unmanned tasks such as delivering incoming goods to the proper location in the warehouse and returning empty pallets to the inbound dock. Existing voice systems can continue to be used by the operator. This new approach can also use the existing warehouse management system (WMS) or be applied to other equipment such as reach trucks.

Challenging Business Environment

Distribution centers face a business environment filled with unprecedented challenges. Retail sales have been very soft and retailers have responded by cutting inventories drastically. The brightest segment of the retail market has been, not surprisingly, private label merchandise, as consumers and businesses switch to lower cost products. Retail sales for 2009 were down 6.2 percent from 2008. Factory utilization has dropped to levels not seen since the great depression. The transportation industry has also seen substantial drops in traffic. Transportation costs were 20.2% lower than 2008 levels, with all modes of transportation being negatively affected.

The Material Handling Industry of America (MHIA) reported that inventory-carrying costs fell by 2% in 2009 due to a 4.6% decline in inventory and a plunge in interest rates. “Although early 2008 saw warehouses full of inventory, by mid-year goods had been drawn down or relocated, leaving facilities with empty space,” the MHIA said.

With sales lower and inventory lower, investment in distribution center automation has naturally taken a major hit. The MHIA estimates that sales of material handling equipment dropped by 35% in 2009 although sales seemed to pick up somewhat in the last half of 2009 and first half of 2010. It's clear that in this challenging environment distribution centers are being forced to reduce costs. Yet few distribution centers will be able to obtain funding for large-scale investments in automation equipment.

One innovative solution that substantially reduces the amount of investment required is upgrading existing equipment, compared to the alternative of starting from scratch. Standard lift trucks from existing suppliers can be upgraded with automation kits that enable them to be automatically dispatched to any area of the warehouse. The automation does not replace the operator but takes over the routine task of driving. This enables the operator to focus on picking goods, which is more difficult and expensive to automate. The lift truck automatically follows pickers from point to point and moves the forks to the correct height. Productivity gains of up to 100% are possible.

Automating Forklifts from Existing Suppliers

A key advantage of this approach is its ability to seamlessly integrate with existing equipment in the distribution center. The automation kits can be installed on all popular makes and models of lift trucks. This is important because most distribution centers have a service contract with one or two lift truck suppliers that typically extends for a considerable period of time. The new approach makes it possible to maintain this contract and continue to work with the same lift trucks covered under the contract, and known to the distribution centers service technicians and operators.

The automation kits provide support for all vehicle types including order pickers, stackers, reach trucks, turret trucks and large counterbalanced lift trucks. The kits support all major navigation techniques including laser, vision, spot and pilot line guidance along with multi-navigation approaches that combine various methods. The kits can support nearly any application so the automated forklifts can continue to be used when needs change, or even be transferred to a different facility.

In addition, automation kits can be installed on the same make and model that the distribution center would normally purchase. Several of the leading lift truck manufacturers are installing the automation kits as factory-installed optional equipment. Installation can also be performed by the automation kit vendor.

Working with Voice Systems and Handheld Terminals

The automated lift trucks can easily be adapted to work with other warehouse equipment. Many distribution centers have voice systems or handheld RF devices to give operators picking information. These systems can continue to perform their existing function. They can also be integrated with the traffic management system that controls the newly automated lift trucks.

The instructions provided by the WMS to the pick-by-voice system or handheld device can be utilized by the traffic management system to guide an automated lift truck through the facility. The traffic management system can also communicate with whatever WMS is used in the facility.

Finally, the traffic management system can use the existing wireless network, which is most often based on the WiFi protocol, to provide instructions to the trucks.

Here's how the new approach works. The WMS simultaneously sends the customer order to the picker and the truck. For example, the picker receives information on his headset that the first pick for a new order is in location 24 in aisle five. The picker walks to that location which will normally be very close to his current location because of optimization provided by the WMS. Simultaneously, the automated lift truck system solution will dispatch the vehicle to arrive at the same time as the operator. The lift truck arrives with the forks positioned at the proper height for efficient and ergonomic order picking. The picker picks the item and the next order line item is then sent to the operator's headset. The truck automatically travels to the next position along with the picker.

When the pallet is almost full, the system sends a new truck with an empty pallet to the picker. The truck with the full pallet automatically travels to the dispatch area. The productivity of the picker is substantially improved because he or she does not need to jump on and off the truck and does not need to drive the truck to the dispatch area.

Automating Other Warehouse Functions

The automated vehicles can deliver goods on pallets from the inbound docks to the locations in the warehouse where they will be stored. In a typical application, the inbound dock operators unload the pallets from the trailer and place them in specially defined lanes near the inbound docks. Notification is sent to the traffic management system by either a photoelectric sensor or by the actuation of a switch at the inbound dock that a pallet or pallets is ready to be picked up.

When an automated lift truck is free, it is dispatched to the lane containing the pallet. The lift truck moves along the lane until a sensor determines that its forks are under the pallet. The truck then delivers the pallet to the proper location in the warehouse. The traffic management system communicates with the WMS when the goods are delivered. In most cases, the goods are then put away by a reach truck driven by an operator. Operator productivity is substantially improved because the operator no longer needs to shuttle back and forth to the inbound dock to pick up incoming goods.

Another application that demonstrates the versatility of this approach involves picking up empty pallets from throughout the warehouse after they have been unloaded, and returning them to the inbound dock. This is typically accomplished by establishing special locations for pallet pickup throughout the warehouse.

After reach truck operators have finished unloading a pallet they place it in one of these locations. The placement of the pallet can be made known to the traffic management system either by placing a photoelectric sensor in the pickup location or by positioning a switch connected to the traffic management system. In either case, once the traffic management system is made aware that a pallet has been dropped off, it uses pre-defined logic to determine when to send an automated lift truck to pick it up. Some distribution centers may prefer to have pallets picked up whenever a lift truck is free while others may want to pick up pallets during hours when picking activity is low.

Wide Range of Benefits

The key advantage of this approach is that it eliminates non-value-added tasks that pickers otherwise need to perform such as jumping on and off lift trucks, raising and lowering forks, fetching empty pallets and delivering full pallets. The time saved translates into higher order-picking productivity with higher number of picks per hour leading to lower operational costs.

These systems can easily be changed to accommodate future changes in warehouse layout, product mix or volume. While a problem with an AS/RS will often shut the entire system down, any problems that may arise with a retrofitted lift truck are limited to the individual lift truck while the rest of the system continues to run normally.

Besides improving productivity, this automated lift truck approach improves safety by eliminating injury-prone tasks such as driving the lift truck, getting on and off the vehicle and ensuring the pallet is positioned at an optimal height for the picker. There is also significantly less risk of collisions with pickers or other automated and/or manual lifts trucks, or damage to goods, even in distribution centers where mixed lift truck traffic is operating within the same aisle.

The automated lift trucks are driven over optimized routes at controlled speeds, helping to avoid injury or damage to goods, saving energy, and providing longer lift truck life with lower maintenance expenses. The result is reduced risk of personal injury with less damage to goods, pallets and racks when compared with manual lift truck operations.

Benny Forsman is business unit manager for Pick-n-Go, from Kollmorgen, providers of motion systems and components for OEMs.

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