Former lab technician Annette Helmich is thrilled to have a new, in-­demand skill and a full-time job to go with it — welding machinery.

While Ms. Helmich started learning her new craft by spending four weeks at a local community college, she says she polished her welding skills on the factory floor of her new employer, AGCO Corp. The Jackson, Minn., global manufacturer of agricultural machinery, which took over iconic names such as Massey Ferguson and Allis-Chalmers, is one of a number of revisiting an old idea. Instead of relying on community colleges or private schools to get skilled workers, companies are again running their own training programs.