There may be an expiration date on when a utility patent is no longer protected (17 years from issuance), but there is no time limit for manufacturers to implement a patented assembly machine or process. Quite often, manufacturers are quick to try a new machine or process. Sometimes, however, it takes many decades for an invention to catch on—and by that time, the patent is long expired and the inventor long dead.
This latter scenario definitely applies to the clinching process in use today to quickly and securely join two or more layers of sheet metal. Back on Oct. 18, 1897, German inventor Dr. Louis Thies was granted a patent for his press-joining system for metal sheets without fasteners. However, the process didn’t catch on in Europe until the mid-1970s, when automotive manufacturers began looking for ways to more quickly join sheet metal.