Economic theory tells us that printing money will inevitably lead to inflation, so why we do not see hyperinflation yet? This article explains it, and here is the analogy used:

 

"My favorite analogy for how printing money doesn't always equal instant inflation is that you can make as many bullets as you want, but those bullets won't do any harm until they're actually fired. Right now, the Fed has printed trillions of bullets, but almost none have been fired. They're all sitting idly in excess reserves."