To the layman, the scene on Fujitsu Fanuc Ltd.'s shop floor in this industrial suburb offers a baffling glimpse into Japan's new age of industrial technology.

The mechanical hands of computer-guided robots shift hunks of metal into the jaws of machines that cut, trim, and drill them into finished machine-tool motors with a precision that once required 20 years of training for a human being.

In one corner, a lone robot tends three machining centers and a drill and it does not stop when the lights go out at quitting time. A switch is flipped by departing workers -- there are only 10 of them in the whole shop -- and the robots keep working for another four or five hours.

A year ago, the 10 workers and 10 robots turned out 3,500 motors. Another 15 robots were added and production nearly doubled in one year.

But company officials explain that is old stuff now. The new work is going on in Fanuc's research labs, where a full one-fourth of the company's employes are designing even more potent technology. One goal, it is casually explained, is the first factory totally operated by robots.

Fujitsu Fanuc's experience is a small but typical example of Japan's new venture into futuristic industry, the wave of high industrial technology that many believe will control the ways of doing business for the rest of the century.

In a major new industrial offensive, Japan has designated the 1980's as the era of creative technology in which it will take the lead in some of the most sophisticated fields -- computers, semiconductors, robots -- and the industries in which they are applied.

The drawing boards abound with new machines with new applications -- robots whose mechanical hands work on the ocean floors or in stifling temperatures where man cannot, machines that can be talked to and that can talk back, computers whose work loads dwarf the present generation's, and robots that make robots.

In several fields, the Japanese will be clashing directly with Americans, who historically have held the edge in developing new industrial technology, if not always in applying it. Some authorities envision a new trade war looming, a more fundamental Japanese challenge than the two countries' past feuding over textiles, automobiles, and steel.

A U.S. House of Representatives trade subcommittee has analyzed the coming competition in such fields as computers, advanced electronics, robots, telecommunications equipment and possibly aircraft. It cited a lack of U.S. industrial policy in comparable fields and floomily predicted "that the Japanese threat in these high-technology areas may soon become the most explosive economic issue between our two nations."

A second report by the subcommittee reexamined those issues last month and declared that "Japan's rate of industrial progress and stated economic goals should be as shocking to Americans as was Sputnik."

The new wave is the third for Japan's postwar economy, now the second-largest in the noncommunist world. First came the industrial staples such as steel mills, power generators and petrochemical plants. In the 1970s, Japan pressed ahead in big consumer products such as automobiles and electronics. In both of those waves, the basic technology was bought or borrowed from the United States and Europe and what brought Japan its leadership was its ingenuity in applying that technology to produce goods.

The third wave, planners say, will be based on indigenous technology, often developed with government subsidies. A visionary projection compiled by the government's Ministry of International Trade and Industry this year observes that little further application is to be found for imported technology and proposes that Japan build its own future with home-grown research and development of "original technologies."

Hard economics dictate the shife, in part. Other flourishing Asian countries such as Singapore, South Korea and Taiwan are catching up with with Japan in several fields and, because of lower wage scales, are starting to compete strenuously. Japan is perpetually worried about energy supplies and the "knowledge-intensive" fields are smaller users of oil and coal. They are also more inflation-proof when oil prices soar.

Hideaki Kumano of the trade ministry describes an era of "creative knowledge-intensive industries" in which Japan will make the most of its major asset, skilled manpower, and use less of what it does not have, natural resources.

It used to be that we thought we had to catch up with other countries," Kumano observed recently. "Now we have caught up. We have to become a technology-based nation."

Some authorities believe Japan already has overtaken the United States in semiconductor technology essential for the advanced computers and mini-computers of the next two decades. American manufacturers are complaining that Japanese government subsidies helped to narrow the gap, creating an unfair trade advantage. The most publicized example is a large research project on applications of very large-scale integrated circuits carried out by five companies. The government contributed about $150 million, nearly half the financial costs.

Japan's computer goals are high. One Japanese company has displaced IBM as the biggest seller in this country, and one authority estimates that by 1985 Japan could be selling between 15 and 20 percent of its computers in the United States.

Japan already is the world's leader in industrial robots, which are in widespread use here. Its goal is a great leap forward in the 1980s. The value of robots produced here in 1985 will be 12 times as great as those in 1978, according to industry sources.

They will also become a major export item. Only 3 to 4 percent of Japan's robots are sold abroad now but by 1985 that proportion will jump to 20 percent and many of them will be sold in the United States, the industry sources predict.

The Japanese government, through research in national universities and government loan guarantees, encourages the robot industry, particularly in developing special machines for performing excessively difficult or fatiguing work.

Indirect subsidies are also used to promote a wider use of robots, in part to push up Japan's already high productivity. Companies that buy robots can depreciate the cost faster than is customary for tax purposes. The trade ministry also guarantees loans to help small and medium companies buy robots.

Most of Japan's robots were developed to take over existing jobs in factories but the new wave, guided by advanced minicomputers, is destined for more exotic tasks. One of the most talked-about projects is the seabed-exploring robot that can work the ocean floor where man cannot. Others are being developed to perform jobs in agriculture and forestry.

Japan is acknowledged to be ahead of the United States and other countries in technology of machine tools, especially the smaller ones, and is rapidly converting its stock to the most advanced ones, which are controlled by numbers fed into tapes and discs. The ratio of these "numerically controlled" machine tools has grown from 8 to 41 percent in nine years, in part because the government has subsidized small-and medium-sized companies to develop them.

The numerically controlled tools assure better quality work than those run by humans and are far more productive. One worker can run several of them and the rule of thumb used by industry experts is that the numerically controlled machine tool is four times as productive as the manned variety.