Toyota eliminates 1.7 million pounds of hazardous waste

Tags: lean manufacturing

Toyota Motor Manufacturing Indiana Inc. (TMMI) has experienced many wonderful accomplishments. Starting in 1999, with 1,700 team members, TMMI began production of Tundra at its new automobile assembly plant south of Princeton, Ind. Sequoia, Toyota’s first full-size SUV, was added to TMMI’s production in 2000. TMMI completed construction of its second plant in 2002. TMMI’s “East Plant” began production of the Sienna minivan. During the first five years of production, TMMI's family grew to include more than 4,800 team members and a production of 370,000 vehicles per year.

Setting its sights on waste
TMMI's ISO 14001 Environmental Management System requires that all environmental aspects and their impacts be identified. TMMI then focuses its resources on those aspects with the largest opportunity for improvement.

Of the items identified, the two most significant sources of hazardous waste were from the following processes:
1. Purge Solvent;
2. Fuel Tank Primer.

Purge solvent is utilized in its painting operations to remove paint from paint application robots when switching from one paint color to another. The color change process consists of the following steps:
1. Initial paint cycle is completed;
2. Purge solvent and air flush the paint line;
3. Different paint color is loaded into the robot;
4. Next paint cycle is initiated.

The hazardous waste generated from the process is flammable and contains numerous solvents, including xylene and toluene. TMMI committed to reducing purge solvent waste from 6.60 pounds per vehicle to 4.95 pounds per vehicle.

Fuel tank primer is a paint-like coating utilized to protect steel fuel tanks from corrosion as well as debris that might strike the tank during vehicle operation. The fuel tank primer application process is relatively straightforward. First, the assembled fuel tank is brought, by overhead conveyor, into the fuel tank primer spray booth. Once inside the spray booth, the fuel tank primer robot coats the fuel tank. Finally, the fuel tank primer is cured in an oven.

Fuel tank primer waste is hazardous due to its use of barium as a corrosion inhibitor. TMMI's reduction goal was to reduce fuel tank primer waste from 1.28 pounds per vehicle to 0.96 pounds per vehicle.

Alternatives Considered
Purge Solvent: Reducing purge solvent usage and waste generation was determined to be as simple as reducing the number of purge solvent color change cycles. By working with Production Planning, TMMI was able to reorganize its production cycles to allow the grouping of like-colored vehicles.

However, there are limits to the number of vehicles that can be color grouped. First, paint technology limits the number of like-colored vehicles that can be color grouped to only three to five. The paint can actually begin to collect on the robot causing inconsistent spray patterns and reduced transfer efficiency. Second, the Toyota Production System requires that vehicles be produced, with their individual options, in the sequence they are ordered by our customers.

Toyota Motor Corporation (TMC), Toyota Technical Center (TTC) and Toyota Motor Manufacturing North America (TMMNA) paint engineering groups developed an ingenious solution to the purge solvent usage/production flexibility problem: cartridge painting. Cartridge painting greatly reduces purge solvent usage. The new system consists of paint robots as before, but color changes are accomplished by simply changing paint cartridges. This cartridge painting system was one of the new environmental technologies being utilized in TMMI’s newly constructed East Plant.

Fuel Tank Primer: First, TMMI explored utilizing fuel tank primers that did not utilize barium. Unfortunately, the barium-free materials were not capable of meeting TMMI's quality standards.

After the disappointing results from the barium-free fuel tank primer trials, TMMI changed its focus to utilizing plastic fuel tanks. Of course, plastic fuel tanks do not require protective coatings to prevent corrosion. By partnering with its suppliers, TTC and TMMI were able to develop plastic fuel tanks suitable for use on trucks and sport utility vehicles.

Hurdles Faced
The greatest hurdle faced with both projects was to maintain product quality during the environmental improvement activities. Each of the hazardous waste reduction activities required production processes to be modified. New equipment and technologies were also developed throughout each of the projects. TMMI's engineering and production team members worked to ensure that TMMI was able to meet customer needs while reducing impact on the environment.

Waste MinimizationResults
TMMI reduced purge solvent waste from 6.60 pounds per vehicle to 3.03 pounds per vehicle. This is an annual reduction of more than 1.3 million pounds of hazardous waste.

TMMI was able to eliminate the fuel tank primer process. The result is a 400,000-pound-per-year reduction in barium containing hazardous waste.

Lessons Learned
Environmental performance is key to success in the 21st century. Energy usage, waste generation and air emissions are wonderful indicators of overall process efficiency. TMMI has found that essentially all environmental improvement activities result in significant cost reductions.