Behind ink on paper, the printed word, and the stunning images found in a book, lies the critical binding step, “spine preparation.” Far too often, spine preparation tools are not properly maintained or forgotten about. If ignored too long, or not properly configured, the binding process can become compromised or fail, resulting in costly resolution.
Proper spine tool selection and maintenance is integral to achieving a quality spine. Paper type and glue are key determining factors in selecting which tools to use and how. Special care needs to be taken to avoid weakening or destroying valuable paper fibers that are critical to obtaining a strong adhesion. And, whether you are using a dust milling head or a shredder head in your milling station to remove the fold of the signature, you need to make sure your knives are periodically sharpened. Many tools today are outfitted with twin tip disposable knives, designed such that you can simply rotate them 180 degrees when worn and re-install them using the opposite (sharp) end.
In most cases, binders are equipped with either two or three of the following spine preparation stations:
- 1st Station. This is typically a leveling saw which is equipped with a large number of roughening teeth. As the name implies, the tool is used to compensate for the uneven trimming of the milling head and to create a greater release and exposure of paper fibers.
- 2nd Station. If binding with hotmelt adhesives, this is normally referred to as the notching tool. However, when binding with PUR adhesive, the notching tool is typically lowered and not used. In some cases, a micro notch may be used with PUR. Notching tools also require periodic maintenance. They are designed such that they can be manually rotated two or three teeth in position in order to utilize a new sharp area of the tool. Don’t forget about checking the position of the backing plate as well.
- 3rd Station. This is usually the home of the fiber rougher head and ring brush which are used for the optimum opening of the paper fibers, in effect preparing the paper edges twice. The tool is also designed to avoid heat build-up which often results in smearing of paper coatings and filler materials. Normally these are equipped with long-life replaceable carbide knives.
- 4th Station. Some binders are also outfitted with a counter rotating belt brush.
Whether you have a ring brush or belt brush, these tools require special care. Worn out brushes are often overlooked. As the last tool in the line-up, they play a critical role in the removal of paper dust. The adhesive needs to bond with the paper fibers and NOT dust. If your brush is worn down too far, it will leave paper dust on the spine and compromise the bind quality. One way to check on the health of your brush is by stopping a book in the clamp after exiting the brush station (before gluing), applying clear box tape to the spine of the book, and then pulling it away. If there is excessive dust on the tape, it’s time to replace the brush.
Depending on how your binder was designed and the available space, some of these tools may be combined into what’s called “Tool Combinations” or “Combi-Tools.” But whatever your bindery’s configuration, make sure that you have a defined periodic maintenance check of your spine prep tooling. A simple way to check is by removing a book after applying adhesive, but before the cover is applied. Let it dry or cure and then cut the book lengthwise down the center of the spine. This will reveal the quality of the spine preparation, depth of notching, as well as allow you to check the quality and amount of glue application. In many cases, it may make sense to purchase a second set of spine preparation tools so you always have a sharp set on hand.
Most importantly, avoid dull tooling and worn brushes. These culprits are often the root cause of weak or poor binding quality. And remember, don’t ignore your spine prep tools—or you may pay dearly! Do not hesitate to contact your Muller Martini Sales or Service Representative to learn more.