Industry demand has boosted Daman Manifolds' business significantly. "We need to hire 10 more workers in the next six months," Davis said.

His challenge: "I'll have to go through 500 applicants just to get the 10 that I need. And there's no guarantee that those 10 hires will work out. (More: Trade school enrollment soars)

The longer it takes him to hire new workers, the greater the risk Davis could start losing business.

Daman Manifolds is not alone.