Since it was founded by his great-grandfather in 1880, Carl Martin Welcker’s company in Cologne, Germany, has mirrored the fortunes of manufacturing, not just in Europe but around the world.

That is still true today. In a pattern familiar to industrial businesses in Europe, Asia and the United States, Mr. Welcker says his company, Schütte, which makes the machines that churn out 80 percent of the world’s spark plugs, is facing “a tragedy.”

Orders are down 50 percent from a year ago, and Mr. Welcker is cutting costs and contemplating layoffs to prevent Schütte from falling into the red.

That manufacturing is in decline is hardly surprising, but the depth and speed of the plunge are striking and, most worrisome for economists, a self-reinforcing trend not unlike the cascading bust that led to the Great Depression.