Nissan North America Inc. says crankshaft forging at its Decherd, TN, Powertrain Assembly Plant is officially under way.

At an opening ceremony this morning, Nissan announced it would invest another $34.7 million to expand Decherd for the fourth time in nine years, this time to add cylinder block casting production in spring 2008.

“Having the forging plant and, soon, the casting plant located next to where these key engine components will be machined and assembled is a major opportunity for Nissan North America,” says Dan Gaudette, senior vice president-North American Mfg. and Supply Chain, in a statement.

The forging plant will be able to make 1.1 million crankshaft forgings annually for Decherd-made engines installed in Nissan and Infiniti models built in Smyrna, TN, and Canton, MS.

Nissan, which invested $48 million in the new forging plant, expects to reach full production next March. Some 60 workers are employed at the new plant, which is connected at the northeast side of the existing Decherd facility.

The casting operation will employ 50 and make 192,000 cylinder block castings annually for Nissan’s 3.5L V-6 VQ series engine, used in the Nissan Altima sedan.