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The cause of the problem related to Ford's use of a transit protection film applied at manufacturing plants to protect the surfaces of vehicles destined for export, says Ghodsi, who headed the project team. The plastic film was expected to protect vehicle exteriors during transit from the plants to U.S. ports, and then through the ocean voyage to the distributors. But during truck and rail transport, portions of the film were lifting away from the vehicle surfaces, and dirt and debris that became trapped between the loose film and the vehicles were producing the defects. The film had to be repaired or replaced at the ports before the vehicles were loaded on the ocean transport vessels.
The Ford Six Sigma team chose a Grand Marquis and Crown Victoria manufacturing plant in St. Thomas, ON, Canada, a port in Delaware, and one destination market, the Middle East region, for its focus.
The team developed a cause-and-effect diagram, or fishbone analysis, to identify potential root causes of transit film-induced defects. Team members examined the Ford process and found several key variables that influenced the surface defect rate:
- Transit film material
- Quality of the written film installation instructions provided to operators
- Operator training and supervision.
Consumer Driven Six Sigma Black Belts at Ford rely on Minitab Statistical Software, supplied by Minitab Inc. (State College, PA), Ghodsi says. So when the team decided to compare the performance of the transit film currently being used at Ford plants with that of a new transit film material, the analysis was done with the Minitab software. The data showed that the new material reduced transit film-induced defects from 2.89 defects per vehicle to 1.29 defects per vehicle, Ghodsi says. Further, the use of the new material would result in a significant cost savings, because it was less expensive.
The Minitab software was also used to demonstrate that operator training, supervision and improved installation instructions could have a positive impact on defect rates. The team compared the performance of two groups of operators. One group was provided with improved training, better film installation instructions and increased supervision; a second group was not. The data showed that vehicles with new film material installed by the group with no training had a defect rate of 1.29 defects per vehicle, compared to a defect rate of 1.04 when films were installed by the group that received training.
The Minitab software's Design of Experiment capabilities helped the Ford team to see how the critical factors interacted, and provided the information needed to make significant process improvements, Ghodsi says. By using the new film material in combination with improved training, increased supervision and better operator instructions, the team was able to reduce defects from almost three per vehicle to slightly more than one defect per vehicle.
The team also discovered that during the domestic transport of the vehicles, an etch-resistant coating applied to vehicle exteriors provided sufficient protection against surface damage. Transit film was only needed for ocean transport. So on the team's recommendation, the transit film application process was moved from the plant in Canada to the port, freeing up 4,500 square feet of manufacturing space in the plant.
The result was a cost savings of more than $500,000 on the Six Sigma project alone, according to Ghodsi. Process changes have now been proposed for 11 other Ford U.S. manufacturing plants, he adds, and transit film installation operations are being relocated to port processing centers.
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- The statistical software helped the project team see how the critical factors interacted, and provided information needed to make significant process improvements.
- Surface defects per vehicle were reduced from nearly to three per vehicle to about one per vehicle.
- The Six Sigma project produced savings of about $500,000.