The quality controls on Muller Martini saddle stitchers guarantee excellent stitching and cutting quality with little production waste. To ensure that the saddle stitchers operate efficiently and with as few errors as possible, the process monitoring system focuses on two areas: product make-up and product quality. The make-up control function looks at section identity and identifies missing sections. In order to achieve optimum quality, the saddle stitchers are equipped with checks to monitor the signature position, cutting quality and stitching.

Patrick Treyer, Product Manager for saddle stitchers at Muller Martini: "The digital workflow does not eliminate all errors in advance. However, it does provide security during set up and when relaying a job to the next machine."

Product Make-up Monitoring
A range of tests guarantees a complete quality product during saddle stitching. The feed monitor, which is integrated into the feeder, recognizes missing sections and ensures that the signature feeding is aborted in the subsequent feeders and that the faulty product is discharged without stitching. The blade monitor checks the feeding of signatures on the gathering chain. If it identifies a missing section, signature feeding for subsequent feeders is again aborted. In the event of a paper jam, the blade monitor stops the machine before more selection accumulate.

The Semko lateral thickness measurer checks each copy against a reference value to make sure it is complete. Incomplete products are not stitched and are ejected before the three-knife trimmer, reducing the amount of production waste. "Semko can be added to all saddle stitchers. Standard mid-range machines are equipped with a ridge caliper as standard," explains Patrick Treyer, product manager for saddle stitchers at Muller Martini. With these two monitoring systems, each individual product undergoes a thickness check on the gathering chain.

Asir 3 is a technological masterpiece: the image and barcode reader offers the most reliable product make-up check for saddle stitchers. A barcode label allows each signature to be identified with absolute reliability. Asir 3 acts as "intelligent camera", comparing the barcodes to determine whether all signatures in a run are identical. If the signatures for all feeders feature an Asir-3 barcode, the sequence of the signatures can also be checked. Asir 3 checks signatures that do not have a barcode using its image comparison mode.

Any signatures that do not match the scanned barcode or barcode/image section that has been accepted by the machine operator are ejected. The system's referencing function, which scans fully automatically, is just as outstanding as its reliability. If the saddle stitcher is equipped with a merchandise tipper, the signature sticker control tests whether the specified card or sample is actually available.

Quality Monitoring
The test steps mentioned ensure that a product is assembled completely and in the correct order in the saddle stitchers. To guarantee the products also correspond to the customer's quality requirements, Muller Martini has integrated further extensive checks for product quality.

In the oblique sheet and long book monitor, photocells check the position and length of each copy. Products that are at an angle on the gathering chain or are not correctly jogged are ejected without being stitched. In the stitching machine, all copies are checked again after stitching. The staple control located at the bottom continually checks whether the staples present correspond with the number entered at set up. After this, the trim monitor in the three-knife trimmer guarantees that each product lies within the adjustable tolerance for the required dimension accuracy. Any products that fall outside the range are ejected.

Optimization with the Optimizer
Monitoring with the optimizer, a sub-function of the data management system, is crucial for process reliability. The optimizer provides the machine operator with clear statistics about incidents during set up and production. As irregularities are displayed for each assembly, the causes of interruptions can be quickly determined and resolved.

The data management system enables a detailed process and error analysis, even without a connection to the digital workflow. In this way, times for each machine relating to set up, production, idle time, faults, interruptions, breaks and repairs can be analyzed, for example.

The optimizer provides the machine operator with clear statistics about incidents during set up and production.

Even More Reliable with the JDF Standard
When using saddle stitchers, customers can obtain additional process reliability by connecting the JDF-compatible saddle stitchers from Muller Martini to a Management Information System (MIS). "The digital workflow does not eliminate all errors in advance," says Patrick Treyer. "However, it does provide security during set up and when relaying a job to the next machine." Quality controls are therefore not superfluous.

Instead of the conventional order ticket, the machine operator receives an electronic job programmed with Job Definition Format (JDF), which contains all relevant data. This means he has a constant overview on the saddle stitcher of the signature to be processed, including the amount and sequence, the cutting length, the (remaining) run and much more. In this way, errors and misunderstandings that arise from spoken and written communication can be eliminated.

The Semko lateral thickness measurer checks each copy against a reference value to make sure it is complete. Incomplete products are not stitched and are ejected before the three-knife trimmer, reducing the amount of production waste.