Differences in Digital Presses

If you hear the term "digital press," what does it mean?  There are companies who manufacture copiers and call them digital presses, and there are digital press companies who make claims about resolution and quality that just don't match the delivered product.

What is all the difference?

1. Process - true digital presses typically involve a different process than copiers.  While there are many high-quality copiers out there, typically, they cannot match the resolution, color quality, or color-matching throughout the process of printing.  True digital presses are usually bigger, because they endeavor to keep the paper flat and away from heat to avoid cracking a folded, printed piece.  Heat is a major factor in the digital printing process, and you can tell the difference in the curl or lack thereof of the printed piece.  True color-matching is a very important piece of a commercial print, and good digital presses will produce a very consistent color match throughout the print.
2. Resolution - Not all digital presses are made equal.  The resolution is a major factor in making a print that comes very close to offset quality.  When examining a print, do you see little square bumps around the images in the finished piece?  Does it look hazy?  This is the result of resolution that is sub-par to the commercial printing environment.  True 1200X1200 DPI (dots-per-inch) resolution or greater completely eliminates this fuzzy edge.  While many companies claim to have this resolution, most derive that resolution through a 600X600 DPI that has been digitally "enchanced" to a greater resolution.  What this means is that the computer makes an educated "guess" at what comes next.  Result = the edge gets fuzzy and pixelated.  True 1200X1200 resolution is very clear and sharp, looking much more like offset.
3. Alignment - the adjustment from the front of the print to the back.  Many companies do not pay attention to this "skew" in the images.  If the alignment is off, the finished, full-bleed prints will look slightly off or askew.  Think of holding the image straight up and down, but having the print on the paper look "a little off"... not straight with the edges of the paper.  This is the result of poor alignment in the machinery that produced the print.  A good digital press will keep the alignment to .5 mm or less front-to-back.  This produces a print that is even with the edge of the paper.
4. Production speed - the page-per-minute of a digital press is critical to getting your printed piece back in time.  A good digital press will have a fairly rapid rate of production that will not slow based on the amount of printed material running through the machine.  60 ppm 4/0 or 30 ppm 4/4 is a good starter speed for digital presses.  The machine should also cool the paper during the process as the rollers tend to heat up during production.  This curls the paper and makes the finished piece brittle.
5. Stability - a digital press should have a great deal of stability in production.  Copiers tend to break very frequently, especially with higher runs.  A true digital press is made for the commercial printing environment, and they are typically very stable in comparison to copy machines.