Actually, you do want your bleeds to print–that’s the whole point. Bleeds output to press, printing on the final sheets. They’re trimmed off during finishing when the paper is cut down on a guillotine. The purpose of extending bleeding artwork beyond the trim size (thus into the bleed area) is so that the extra art survives until cutting. Because paper, cut in large stacks, can shift slightly on the cutter, even a half-point shift can leave an ugly white strip down one or two edges of bleeding artwork. Extending bleeding edges out 1/8th-inch (0.125-inches) ensures that, should a minor shift occur during cutting, there will be no white stripe.

By the same token, you need to make sure that the critical elements of your design are 1/8th-inch inside the trim area (this inner space is called the live area) so that, if paper shifts during cutting, nothing important is cut off.

Now, as to whether your printer knows that your bleed area is indeed part of the bleed overage not part of the trim size… Communicate with the printer. When creating your PDF, you should add cropmarks as well (available in most PDF export options), but also talk to the printer, noting the desired trim size and the inclusion of the bleed area.

Derrick