When AAP St. Marys Corp. learned last year that a portion of the aluminum wheels it manufactures and ships to Japan were arriving damaged and unusable, finding the source of damage became a top priority. "We had to examine all of our packaging and shipping components and procedures," says Elaine Lochtefeld, production control shipping supervisor at the St. Marys, OH, company.
Japanese auto manufacturers were receiving wheels that had a white haze on their surface, and in certain instances the substance had eaten through the wheels' sealant layer. This meant that AAP St. Marys had to bear the cost of shipping the rejected wheels back to the U.S., correcting the problem and reshipping them to Japan. The company ships an average of 7ꯠ wheels per month to Japan.
Lochtefeld soon discovered the culprit was the polyethylene foam that was being placed on top of each layer of wheels as a protective cushioning material.
"Because the load spends most of its time in a container on an ocean-going vessel, it is subjected to quite a bit of vibration and intense heat," Lochtefeld explains. The heat caused the PE foam to melt and attack the wheel coating. The rough seas caused the wheels to slide around a bit, which sometimes scratched or marred the wheels due to the PE's abrasive surface.
With the cause of the problem figured out, Lochtefeld began looking for a different kind of cushioning material. She chose Microfoam® closed-cell polypropylene foam from Pactiv Inc. (Duluth, GA). Its high melt point of 320F made it suitable for handling parts or packaging environments that reach elevated temperatures. And at 1/16" thick, sheets of Microfoam PP are half as dense as the PE foam sheet. That low density results in low weight, which reduces shipping costs.
Additionally, Microfoam has a high coefficient of friction. In other words, the foam grips the wheels better than the slicker PE, causing the wheels to slide around less when shipments encounter choppy waters.
Before Lochtefeld made the decision to use Microfoam, she sent samples of the materials along with competitive materials to an independent testing lab, G&H Packaging & Testing (Fairfield, OH).
"We had the lab simulate a variety of conditions. Everything from shock, drop, vibration, temperature, humidity and so on," she says. "Microfoam PP came out the clear winner. We even discovered that thicker materials didn't perform as well as Microfoam PP, and they were more expensive."
A positive change
AAP St. Marys switched to Microfoam in January '98 with positive results. "When [the wheels] arrive, they go through approximately 20 different quality checks. Since the switch, we haven't had a single wheel returned because of damage from packaging components," Lochtefeld says. About 7% to 10% of the wheels shipped to Japan had to be sent back to AAP St. Marys before the company switched foams. Although AAP St. Marys' contract with Japanese automakers has expired, it is using the microfoam PP to ship wheels domestically.
A standard AIAG (Automotive Industry Action Group) returnable high-density PE tray from TriEnda Corp. (Portage, WI) is used to transport the wheels, and each wheel is placed in a molded recess. Each layer of eight wheels is then topped with Microfoam before a new tray is stacked on top. Depending on the size of the wheels, each pallet load carries between 30 to 48 wheels stacked five layers high. AAP St. Marys uses 40"x48" pallets.
A semi-automatic sheeter, also from Pactiv Inc., is used to dispense a pre-programmed length of Microfoam sheet. The material is supplied in 60"-wide rolls through M&R Flexible Packaging (Dayton, OH). Workers position a 60"x60" sheet on each layer of trays. Once the trays are loaded and palletized, they are stretch-wrapped and banded to help keep the load secure for shipment.
