The slowdown in molding and machining orders in the Americas because of the slumping industrial sector contributed to an 8.5 percent drop in Proto Labs Inc.'s second-quarter profit.

The Maple Plain-based prototype maker's stock sank 13 percent Thursday on the news.

The company also said global expenses soared due to upticks in hiring, R&D and marketing, also contributing to the drop in earnings.

The company, which specializes in contract milling, injection molding and 3-D printing services, reported second-quarter sales that bolted 17 percent to $75 million. Profits were $10.7 million, or 40 cents a share.

Excluding one-time costs, including those related to last year's acquisition of Alphaform AG in Germany, profits were 45 cents per share, which missed expectations.

On average, analysts had forecast earnings of 48 cents and revenue of $77 million.

The stock fell $8.04 to close at $53.29 per share Thursday. It had hit its 52-week high of $82.06 a share in early spring.

In a statement, Proto Labs CEO Vicki Holt said she was generally pleased with the quarter.

"Revenue growth was solid in the second quarter, driven by continued strong growth in 3-D printing, strength in our European markets and the contribution from Alphaform," Holt said. "We were also pleased with the legacy growth in Europe in the quarter, which grew 24 percent. And we saw an improved performance in Japan with a revenue increase of 46 percent year over year."

In the Americas, however, she said growth was slower than expected in injection molding and CNC machining, citing a slowdown in the U.S. industrial economy and leadership changes.