Realizing the Elusive ‘Book-of-One’ Production Model
Publisher’s of all stripes are after the same goal: an inventory-less workflow in which unique books can be seamlessly printed and bound, one after the other. The capability to do the printing part of that equation is here already. Assuming you have a somewhat common size, varying page counts (and matching covers) are no big challenge for today’s high-speed digital printers.
It’s the finishing part that gets a little sticky. A large portion of the books that are digitally printed are soft-cover titles. These books are adhesive perfect bound, either using conventional hot-melt or PUR-reactive glues. As digital press output rates have climbed, the bottleneck has proven to be the binder.
In an offset plant, perfect binders may scream along at 18,000 books per hour (mph). But that’s possible because they’re running the same format book. In order to exceed a throughput rate of about 500 (perfect-bound) bph, you need a multi-clamp binder. Configurations range from four clamps up to 21 or more.
The catch is, when running “books of one”—where page counts vary in each book block—each clamp must be “set” for the bulk of that book block. The clamp measurement also impacts the side-glue settings and any scoring that’s applied to the cover. Block thickness drives all of these.
In a normal bindery run, these components are set once, and then it’s off to the races. But if there are big variances in products when running “books of one,” then each clamp must be set for every book block. This is not an instantaneous process (although it’s pretty quick).
Even for the most technically sophisticated binders, it may take 2-3 seconds for clamp settings to change. From there, it’s simple math. This process could limit binder output to approximately 1,200 bph, or less.
This becomes a roadblock for an inkjet press capable of printing in excess of 3,000 bph. There are various methods by which a binder sets itself for the book block. Some systems will induct the block into a “measuring station” where various automated measuring methods will determine the block dimensions