Quality Stitching Wire Matters
by Kristopher Shaw, sales manager
WCJ Pilgrim Wire
Stitching wire is one of the last items a printer or binder thinks about; however, there have been some interesting changes with stitching wire in the last few years, including the increase in the use of colored stitching wires (PET coated and alloys) and the use of stainless steel wires used in specialty production runs. The wires used in binding or finishing departments are in the form of saddlestitching, loop stitching, bookletmaking, side stitching, inline press stitching and corner stitching.
As the industry has evolved, so has stitching wire. Quality of wire, path of wire, wire delivery, spool sizes and de-spooling equipment are all major factors in how stitching wire is going to perform in the field. With the continued demand for increased run speeds and overall profit, high-quality stitching wire and proper machine set-up are a must for today’s binding/finishing departments.
Quality of wire
An ideal wire is chrome-like in appearance with special friction-reducing additives to resist peeling and flaking. It provides a superior workability while forming into a staple.
Stitching wire is not straight. Each wire package has a desired curvature of the wire. The radial or circular curvature is known as “cast.” Cast is measured as the diameter of a free turn of wire. The axial component is referred to as “camber.” Camber is measured at the offset in the ends of one turn of freely hanging wire. Larger cast and smaller camber are characteristics of a high-quality wire. This allows the wire to go into the stitching head more smoothly, producing less drag, and will provide fewer dropped stitches. In turn, the stitching head will work more efficiently with less energy and with less maintenance. So, checking on the straightness of the wire can be very important.
Path of wire
A clean path for the stitching wire from the spool to the stitching head is critical in getting a positive stitching outcome. The coating can be easily chipped, scraped or damaged by running the wire past an unprotected steel bracket, worn wire guides, spring tubes or dirty felt pads. The felt pads must be checked frequently, oiled and rotated, or replaced, on a regular schedule. Wire guide springs and felt pads are a normal wear part on any stitching head. Flat spots on guides and springs, along with a dirty felt pad wiping system, can cause flaking issues that will jam the stitching head, stop production and cause additional maintenance and repair costs.
The right size wire for the job
The majority of stitching wires used in today’s binderies and inline stitching operations are 24 and 25 gauge. These two gauge sizes amount to a 21.3 percent difference in product yield, which translates into 21.3 percent more staples when using a 25 gauge over 24 gauge. In simpler terms, imagine if a staple or stitch is one inch: that would allow for 2,304 more staples by using the 25 gauge wire over 24 gauge.
Recommended stitching wire gauge
- 25 gauge stitching wire is the recommended thickness for work that is 1/16 to 7/32 of an inch.
- 24 gauge stitching wire is the recommended thickness for work that is 1/16 to ¼ of an inch.
These are only suggestions as paper type, density, coatings and stitcher set-up can change the stitching wire size required. Larger diameter wire substantially affects the yield of the wire, along with the increase in the amount that will be paid in postage.
Spool sizes, de-spooling equipment and winding
Stitching wire comes in many different packages and generally ranges from 5lbs to 1,000lbs in size. Primary usage and machine type determines the size of spool required, but running speeds and space availability also play a crucial role.
Standalone stitchers that are hand fed usually use five or 10lb spools. Collators with stitchers used for short-runs of five to 10,000 books also can use this type of spool. Saddlestitchers for longer, mid-range runs will use 35, 40 and 70lb spools. High-speed collator/stitchers and web operations using inline stitchers will use 200lb, 650lb smart-drum and even larger 1,000lb smart-pull wire systems.
A larger spool or drum has economical and production advantages. Larger packages cost less per pound of stitching wire to manufacture, and larger packages require fewer spool changes during the manufacturing process.
Utilizing larger wire packages will reduce spool changes, thus increasing the output of books per hour. A normal spool change averages two minutes per spool changed, and generally a saddlestitcher runs anywhere from two to four stitcher heads at a time. With four stitcher heads running a job of over 100,000 pieces with 5lb spools, a saddlestitcher would be stopped for spool changes a minimum of 16 minutes alone. Changing to a 35lb or 40lb spool would wipe this changeover time to zero.
Different size packages have different characteristics that can give the end user advantages. For instance, as stated earlier, a larger circle diameter improves the performance of stitching heads with less friction due to less straightening required and fewer dropped stitches. The larger diameter packages, such as the 650lb smart-drum and 1,000lb smart-pull spools, have larger circle diameters to improve stitcher head performance since less straightening is required.
Proper de-spooling equipment is essential to complement the high-quality wire being used. Matching the correct de-spooler with the spool is essential to problem-free production.