TOKYO - With ``back to basics'' as their guiding philosophy, Japanese carmakers have put on hold plans to expand plastics applications while they shore up sagging operations. The major exception is Toyota Motor Corp. of Toyota, Japan, which, with a one-third share of vehicle production in Japan, single-handedly could change the industry's materials matrix. Other manufacturers, including ailing Nissan Motor Co. Ltd. of Tokyo, are hoping to delay product innovations.
As recently as three years ago, industry analysts were predicting that Japanese cars would have at least 10 percent plastic content by 1995. They projected further increases to 15 percent, even 20 percent, by the year 2000.
Those upbeat forecasts fell by the wayside when the ``bubble economy'' burst and the yen shot up to historic highs two years ago. The nation's carmakers, forced to shift gears in an effort to restore profits, have turned their focus away from weight reduction and the environment to cost-cutting.
``Ten percent is an evolutionary goal,'' said Shuji Ozawa, vice president and senior analyst at Merrill Lynch Japan Inc. of Tokyo. ``No one really knows when it will be achieved.''
Naoko Suga, chemicals analyst at S.G. Warburg Securities (Japan) Inc. of Tokyo, added: ``Switching to plastic components requires enormous capital investment. And with the industry retrenching, carmakers aren't likely to `experiment' again with plastics until business picks up.''
A 1992 survey by the Japan Automobile Manufacturers Association of Tokyoreports that plastics declined as a percentage of total vehicle weight for the first time in nearly 20 years. The plastics share on 1992 model cars fell to 7.3 percent, from 7.5 percent in 1989 when a similar survey was conducted. Back in 1973, plastics accounted for just 2.9 percent of the average weight of a car in Japan.
As expected, in light of efforts to reduce overall vehicle weight, steel continued to fall - to 70.2 percent, from 72 percent in 1989. In surveys conducted in 1973 and 1983, steel accounted for 77.9 percent and 73.8 percent, respectively, of the average weight of a Japanese car.
In contrast, nonferrous metals such as aluminum, copper, lead and zinc rose to 8 percent, from 7.4 percent in 1989. In 1973 and 1983, nonferrous metals stood respectively at 5 percent and 5.6 percent.
Toshiyuki Ohba, a senior research official at Nissan, said most components that could be switched to plastics already have been converted. These include bumpers, instrument panels and interior trim.
According to Ohba, this conversion process - which began in the mid-1980s - largely was completed by 1990.
``For the time being, we plan to stay at current levels - or about 225 pounds of plastics per car,'' he said.
Japanese cars now weigh an average 2,640 pounds, up 20 percent from a decade ago.
Functional components - those involving starting, stopping or turning of a car - are just at the beginning stages of conversion. For instance, Toyota introduced a carbon-fiber-reinforced plastic propeller shaft for the 1992 Mark-II. The company followed that development with a sheet molding compound cylinder head cover for the 1994 Hilux.
Nissan last year introduced a polyetherketone turbocharger impeller for the Laurel. The automaker also has adopted a nylon 6/6 rocker cover for most models currently in production and a fiberglass epoxy suspension leaf spring for the Largo and Serena minivans.
Nissan; Toyota; Mazda Motor Corp. of Hiroshima; and Mitsubishi Motors Corp. and Fuji Heavy Industries Ltd., both of Tokyo,all have introduced plastic fuel tanks. Nissan equips an estimated 30 percent of its cars with plastic fuel tanks, the most among Japanese automakers.
Cost is the principal reason plastics are not being used for outer body panels in Japan. Nearly twice as expensive as steel, plastics are cheaper only in small production lots.
The break-even point is estimated at 600 units - below 600, plastic panels are less expensive; above 600, the advantage goes to steel.
This stands in contrast to the United States, where steel and plastics break even at 7,000-8,000 units.
Besides cost, most Japanese car manufacturers no longer feel a sense of urgency to replace steel with plastics to improve fuel economy. The reason: Theyhave made progress in other areas that affect fuel efficiency, such as upgrading engine performance, simplifying and redesigning components, and improving aerodynamics.
In addition, since 1990, the peak production year for the Japanese automotive industry, volume demand for plastics actually has declined in proportion to the drop in vehicle output. In 1990, Japanese automobile manufacturers consumed an estimated 2.1 billion pounds of plastics.
Safety is another consideration. Nissan, in designing the Be-1, Pao, S-Cargo and Figaro, all of which featured plastic body panels, adopted plastics only for front fenders and hoods - not for doors, roofs or rear fenders.
Nissan researchers contend these are the only areas in which plastics could be employed without adopting steel reinforcements.
Ohba explained that front fenders are affected the least during impact. The automaker, as a result, did not even bother to conduct side impact tests on plastics.
Hiroyuki Itoh, project manager for Honda Motor Co.'s Civic, added: ``If we use plastic panels, we must reinforce them with steel. There will be no weight reduction, thus it makes no sense to use plastics.''
Japanese automakers also believe steel and aluminum offer superior surface quality to plastics and are easier to fit within existing body assembly and paint processes. Color matching notwithstanding, ``transfer efficiency'' for applying paint to plastics is inferior to metals - thus more costly.
Researchers add that there is still no comprehensive plastics recycling structure in place.