SHENZHEN, China — Inside one of the world’s largest electronics factories, Yuan Yandong, 24, sits on a stool six nights a week, 12 hours a night barring meal and bathroom breaks, and assembles computer hard drives for an American company called EMC.

Until a few months ago, he lived in northern China, where he grew up on a farm and worked at a local hotel after finishing middle school. But this year, he traveled 36 hours by train to Guangdong Province in the southeast to find work in Shenzhen. All he took for his journey south on the hard train seat was a sack of clothes, toothpaste, shampoo and his mobile phone.

“Friends in my hometown said wages at Foxconn were good,” he said. “So I figured I could earn more here.”

A series of puzzling suicides at Foxconn and labor strikes at Honda auto parts factories in southern China have put the spotlight on what work is like inside the country’s booming factories. Analysts say rising wage pressure and demands for better conditions are threatening China’s competitive advantage and raising questions about whether its manufacturing model can continue to churn out much of the world’s toys, textiles and electronics at rock-bottom prices. To do so, China will need legions of young migrants like Mr. Yuan to continue to make the journey from villages in the interior to the manufacturing hubs along the coast.