Shifting gears

by Del Williams
A custom, level-cart pushback rack configuration keeps the carts and the unstrapped pallets flat and secure.

A new product launch is usually a reason for celebration, but at Hyundai Powertech, making room for the parts needed was giving warehouse staff the gears.

As a main auto parts manufacturer of Hyundai Motor Group, Hyundai Powertech specializes in automotive transmissions. The company manufactures a full line of transmission parts, from compact to full-size, that complete more than 600,000 transmissions annually.

Staff needed to make room at company’s Georgia manufacturing facility for the additional assembly parts required for a new eight-speed transmission product. However, warehouse space was tight and the double selective upright rack previously used in the area was insufficient to receive the additional parts, according to Yong Kim, the facility’s material department assistant manager.

Kim turned to Mathand, a turnkey material handling systems integrator out of Georgia, to resolve the issue. Mathand recommended pushback pallet rack from Steel King Industries, a storage system and pallet rack manufacturer.

Dynamic racking for easy access

Pushback rack offers up to 90 percent more product storage than selective rack. Unlike static, single-pallet deep selective racks, a dynamic pushback rack system allows storing pallets two- to five-deep while providing easy access to a variety of different SKUs.

Pallets are stored behind each other in a series of nested carts and are loaded from the same side of the system, eliminating separate aisles for each function. With a stable rack, along with a series of inclined carts and rails, when one pallet is pulled, the one behind it rolls forward.

Every pushback rack system is made to order, allowing the racking to accommodate requirements such as for weak-pallet support, non-standard pallet sizes, and other special pallets.

Unique requirements

After a factory tour, initial drawings of the system were completed. However, an ongoing discussion among the three companies revealed a unique material handling issue that needed to be addressed.

“Our eight-speed transmission parts are heavy and very sensitive,” explains Kim. “Most parts are packed in small plastic boxes and stacked on plastic pallets. The pallets arrive strapped down, but our work process involves us unpacking a portion of the parts and then repacking and racking the rest. These partially packed pallets are more susceptible to tipping over, so it is important they are properly secured.”

As a solution, Mathand recommended a custom, level cart pushback rack configuration, designed to keep the carts and the unstrapped pallets flat and secure.

“We suggested a level pushback cart and a level first pallet position so when the carts are pushed back or ride down the inclined rail slope, the pallets will always remain level,” notes Matt Davis, a Mathand product specialist involved with the project.

Clever solution

According to Davis, achieving this custom configuration required numerous design iterations in cooperation with Steel King engineers, who provided CAD drawings as needed.

“Instead of the cart following the angle of the rail, the front of the cart is raised, so it is taller in front and shorter in the rear,” explains Davis. “On a flat surface, the cart and pallet would seem to be leaning back, but going downhill on the pushback rails they are completely level. This design allows the cart to roll down the rails by gravity without it sloping at an angle.”

Safety from every angle

Because Hyundai Powertech placed a priority on safety, Mathand also worked with Steel King to create custom stops on the cart to prevent double loading of pallets onto the cart.

“Now when a forklift operator loads the first pallet position, he cannot set it onto the cart incorrectly at an unsafe angle,” says Davis. “This helps to ensure proper loading and prevents the pallet from potentially tipping over.”

Strong and secure

In Phase I of the project engineers chose SK3000 pallet rack, a rugged bolted rack with structural channel columns for added strength. Compared to typical racking, the pallet rack, constructed of hot-rolled structural channel column with full horizontal-diagonal bracing, offers greater frame strength, durability and cross-sectional area. Using all grade-five hardware provides greater shear strength, and a heavy seven-gauge wrap-around connector plate ensures a square and plumb installation with a tighter connection and greater movement resistance.

According to Davis, four double bays, four levels high, by two deep were constructed for 64 pallet positions of pushback rack in a space-constricted area for Phase I.

“The pushback rack provides double the storage capacity of selective rack, and four times that of floor storage in the same space,” says Davis.

Three-level pushback

Phase II of the project involves creating another 40 bays of pushback rack to provide enough storage for the assembly parts required for Hyundai Powertech’s eight-speed transmission product launch. For safety, this uses the same level pushback cart design, but has three levels with a carton flow pick system on the bottom and two levels of pushback rack on top.

However, to save cost, the project customized Hyundai Powertech’s existing SK2000 selective rack, a boltless, closed tubular upright product. Compared to open back roll-formed columns, the closed tubular uprights are 44 times more torsion/twist resistant, with 250 percent greater frontal impact resistance and 68 percent greater side impact resistance.

Maximizing storage

With Phase II of the project currently underway, Kim is projecting significant benefits.

“The 40 bays of pushback rack will provide about 31 percent more storage than double-sided selective rack,” he says. “In terms of safety and efficiency, forklift operators will only need to load and unload from one side, instead of two, which minimizes forklift travel and potential collision or rack impact.”

“Any warehouse that requires greater storage density should consider pushback rack,” Kim concludes. “Customizing it can help with specialized warehouse applications, such as those handling small, sensitive or heavy products.”

Del Williams is a technical writer based in Torrance, California.